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Installation and Operation

Tracer™ ZN517Unitary Controller

CNT-SVX12C-EN

April 2005

Tracer ZN517 Unitary Controller Installation and Operation

This guide and the information in it are the property of American Standard Inc. and may not be used or reproduced in whole or in part, without the written permission of American Standard Inc. Trane, a business of American Standard, Inc., has a policy of continuous product and product data improvement and reserves the right to change design and specification without notice.

Although Trane has tested the hardware and software described in this guide, no guarantee is offered that the hardware and software are error free.

Trane reserves the right to revise this publication at any time and to make changes to its content without obligation to notify any per-son of such revision or change.

Trane may have patents or patent applications covering items in this publication. By providing this document, Trane does not imply giving license to these patents.

The following are trademarks or registered trademarks of Trane: Trane, Tracer, Tracker, Rover.

The following are trademarks or registered trademarks of their respective companies or organizations: LonTalk and Neuron from Echelon Corporation.

Printed in the U.S.A.

© 2005 American Standard Inc. All rights reserved.

™ ®

™ ®

CNT-SVX12C-EN

NOTICE:Warnings and Cautions appear at appropriate sections throughout this manual. Read these carefully:

WARNINGIndicates a potentially hazardous situation, which, if not avoided, could result in death or serious injury.

CAUTIONIndicates a potentially hazardous situation, which, if not avoided, may result in minor or moderate injury.

It may also be used to alert against unsafe practices.

CAUTIONIndicates a situation that may result in equipment damage or property damage.

The following format and symbol conventions appear at appropriate sections throughout this manual:

IMPORTANTAlerts installer, servicer, or operator to potential actions that could cause the product or system to

operate improperly but will not likely result in potential for damage.

This symbol precedes a procedure that consists of only a single step.

Note:

A note may be used to make the reader aware of useful information, to clarify a point, or to describe options or alternatives.

CNT-SVX12C-EN

Table of contents

Chapter 1 Overview and specifications . . . . . . . . . . . . . . . . . . 1

Product description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Clearances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Power. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Operating environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Storage environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Agency listing/compliance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Factory default temperature setpoints . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Additional components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Power transformer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Zone temperature sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Discharge air temperature sensors. . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Damper actuators (optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Chapter 2 Mounting the controller . . . . . . . . . . . . . . . . . . . . . 7

Location recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Mounting recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Chapter 3 Applications for the

2-heat/2-cool configuration. . . . . . . . . . . . . . . . . . 9

Wiring requirements and options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

DIP switch settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Binary outputs for 2-heat/2-cool applications . . . . . . . . . . . . . . . . . . . . 13

Binary output 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Overriding binary outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Binary inputs for 2-heat/2-cool applications. . . . . . . . . . . . . . . . . . . . . . 14

BI1: Occupancy or generic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

BI2: Fan status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

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Table of contents

Analog inputs for 2-heat/2-cool applications . . . . . . . . . . . . . . . . . . . . . 15

AI1: Universal 4–20 mA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

AI2: Outdoor air temperature or generic temperature . . . . . . . . . . 17

DAT: Discharge air temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

ZN: Zone temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

SET: Temperature setpoint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Chapter 4 Sequence of operations for the 2-heat/2-cool

configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Power-up sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Cascade zone control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Simplified zone control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Occupancy modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Occupied mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Unoccupied mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Occupied standby mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Occupied bypass mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Timed override control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Outdoor air damper operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Fan operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Peer-to-peer communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Economizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Discharge air tempering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Demand control ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Unit protection strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Filter-maintenance timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Fan off delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Fan status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Chapter 5 Applications for the 4-cool configuration . . . . . . 27



Binary outputs for 4-cool applications . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Binary output 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31


Binary inputs for 4-cool applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

BI1: Occupancy or generic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

BI2: Fan status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Analog inputs for 4-cool applications . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

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Table of contents

AI1: Universal 4–20 mA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33


DAT: Discharge air temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35


SET: Temperature setpoint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Chapter 6 Sequence of operations for the 4-cool

configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Power-up sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Cascade zone control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38


Occupancy modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Occupied mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Unoccupied mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39



Timed override control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Outdoor air damper operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Fan operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41


Economizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Discharge air tempering. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42


Unit protection strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42


Fan off delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Fan status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Chapter 7 Applications for the heat pump configuration . . 45



Binary outputs for heat pump applications . . . . . . . . . . . . . . . . . . . . . . 49

Binary output 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49


Binary inputs for heat pump applications . . . . . . . . . . . . . . . . . . . . . . . 50

BI1: Occupancy or generic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

BI2: Fan status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Analog inputs for heat pump applications . . . . . . . . . . . . . . . . . . . . . . . 51

AI1: Universal 4–20 mA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

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Table of contents


DAT: Discharge air temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53


SET: Temperature setpoint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Chapter 8 Sequence of operations for the heat pump

configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Power-up sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Cascade zone control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56


Occupancy modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Occupied mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Unoccupied mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57



Timed override control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Outdoor air damper operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Heating or cooling mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Fan operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Compressor operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Reversing valve operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Economizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Discharge air tempering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60



Unit protection strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61


Fan off delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Fan status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Chapter 9 PID control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

What PID loops do. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

PID calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Proportional calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Integral calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Derivative calculation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Sampling frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

PID loop action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Direct action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

iv CNT-SVX12C-EN

Table of contents

Reverse action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Error deadband . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

Adjusting error deadband for modulating outputs . . . . . . . . . . . . . 69

Adjusting error deadband for staged outputs . . . . . . . . . . . . . . . . . 69

Other PID settings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Troubleshooting procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Tips for specific problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Changing the sampling frequency . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Changing the gains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Chapter 10 Status indicators for operation and

communication. . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Test button. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Manual output test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Service Pin button. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Interpreting LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

Diagnostic types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

Table of diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Chapter 11 General wiring information . . . . . . . . . . . . . . . . . . 81

Input/output terminal wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Wiring specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

HVAC unit electrical circuit wiring . . . . . . . . . . . . . . . . . . . . . . . . . . 82

AC power wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

Communication-link wiring and addressing . . . . . . . . . . . . . . . . . . . . . 86

Chapter 12 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

Initial troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

Diagnosing operational problems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

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Table of contents

vi CNT-SVX12C-EN

Chapter 1

Overview and specifications

This guide provides installation and configuration information for the Tracer ZN517 unitary controller, as well as a description of its operations. The overview includes a product description, specifications, and descrip-tions of ancillary products that may be necessary.

Product descriptionThe Tracer ZN517 is an application-specific controller that provides direct digital, zone temperature control. The controller can operate as a stand-alone device or as part of a building automation system (BAS). Communication between the controller and a BAS occurs via a LonTalk communication link, which is based on the LonTalk® protocol.

The controller is designed to be field-installed and is sent from the factory configured for a 2-heat/2-cool application. You can change this configura-tion using the DIP switches located on the circuit board. The Tracer ZN517 supports the following three configurations:

• 2-heat/2-cool with optional economizer control• 4-cool with optional economizer control• Heat pump with optional economizer control

Features such as discharge air tempering and demand control ventilation can be configured using the Rover service tool.

DimensionsPlastic-cover model dimensions

For complete dimensional drawing, see Figure 1 on page 3.

• Height: 5.375 in. (137 mm)• Width: 6.875 in. (175 mm)• Depth: 2 in. (51 mm)

Note:

For information about using the Rover service tool, see the Rover Operation and Programming guide (EMTX-SVX01B-EN).

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Chapter 1 Overview and specifications

Metal-cover model dimensions

For complete dimensional drawing, see Figure 2 on page 3.

• Height: 9.0 in (25 mm)• Width: 10.37in. (263 mm)• Depth: 2.25 in. (58 mm)

ClearancesFor wiring, ventilation, and maintenance, provide the following minimum clearances for the module:

Plastic-cover model (see Figure 1 on page 3)

• Front: 4.0 in. (102 mm)• Each side: 1.0 in. (25 mm)• Top and bottom: 4.0 in. (102 mm)

Metal-cover model (see Figure 2 on page 3)

• Front: 24.0 in. (610 mm)• Each side: 2.0 in. (51 mm)• Top and bottom: 1.0 in. (25 mm)

PowerThe transformer must meet the following minimum requirements for the controller and its output devices:

• 19–30 Vac (24 Vac nominal)• 50/60 Hz• 9 VA and 12 VA maximum per binary output utilized

Operating environmentOperate a Tracer ZN517 unitary controller in an indoor environment that meets the following requirements:

• Temperature: From –40°F to 160°F (–40°C to 70°C)• Relative humidity: From 5–90%, noncondensing

2 CNT-SVX12C-EN

Operating environment

Figure 1. Plastic-cover model dimensions and clearances

Figure 2. Metal-cover model dimensions and clearances

1 in.(25 mm)

4 in(102 mm)

5.625 in(143 mm)

6.31 in.(160 mm)

4 in(102 mm)

5.375 in (137 mm)

Clearances

Dimensions

4 in(102 mm) 6.875 in

(175 mm)

2 in. (51 mm)

9 in.(229 mm)

2 in.(51 mm)

24 in.(610 mm)

10.37 in.(263 mm)

width with cover

1 in.(25 mm)

2.25 in.(58 mm)

2 in.(51 mm)

1. 875 in.(48 mm)

1 in.(25 mm)

0.28 in.(7 mm)

9 in.(229 mm)

6.5 in.(165 mm)

Clearances

Dimensions

1 in.(25 mm)

10.25 in.(260 mm)

width without cover

7 in.(178 mm)

CNT-SVX12C-EN 3


Storage environmentIf you are storing a Tracer ZN517 unitary controller for a substantial amount of time, store it in an indoor environment that meets the following requirements:

• Temperature: From –40° to 185°F (–40° to 85°C)• Relative humidity: From 5–95%, noncondensing

Agency listing/complianceCE—Immunity: EN50082-2:1995

EN61000-6-2:1999

CE—Emissions: EN61000-3-2:1995

EN61000-3-3:1995EN50081-1:1992 (CISPR 22)EN55011:1998, Class B

UL and C-UL 916 listed:

Energy management equipment

UL 94-5V (UL flammability rating for plenum use)

FCC Part 15, Class A, CFR 47

Factory default temperature setpointsThe Tracer ZN517 unitary controller relies on a number of temperature setpoints to control HVAC equipment. Table 1 gives the factory defaults for these setpoints, which can all be edited with the Rover service tool or a BAS.

Table 1. Factory default temperature setpoints

SetpointsFactory defaults

°F (°C)

Default setpoints

Occupied cooling 74.0°F (23.3°C)

Occupied standby cooling 78.0°F (25.6°C)

Unoccupied cooling 85.0°F (29.4°C)

Occupied heating 71.0°F (21.7°C)

Occupied standby heating 67.0°F (19.4°C)

Unoccupied heating 60.0°F (15.6°C)

Occupied setpoint limits

Cooling setpoint high limit 110.0°F (43.3°C)

Cooling setpoint low limit 40.0°F (44.4°C)

4 CNT-SVX12C-EN

Factory default temperature setpoints

Heating setpoint high limit 105.0°F (40.6°C)

Heating setpoint low limit 40.0°F (44.4°C)

Discharge air limits

High limit 170.6°F (77.0°C)

Low limit 37.4°F (3.0°C)

Control point high limit 150.8°F (66.0°C)

Control point low limit 44.6°F (7.0°C)

Outdoor air damper setup

Economizer enable temperature 53.6°F (12.0°C)

Table 1. Factory default temperature setpoints

SetpointsFactory defaults

°F (°C)

CNT-SVX12C-EN 5


Additional componentsThe following components are required for proper equipment operation. They are not included with the Tracer ZN517 unitary controller. Addi-tional components may also be required besides those described in this section, depending on your application.

Power transformer

A transformer providing 24 Vac is required to power the Tracer ZN517 unitary controller and associated output relays and valve and damper actuators (see “AC power wiring” on page 85).

Zone temperature sensors

Table 2 shows some of the Trane zone temperature sensors that are sup-ported by the Tracer ZN517 unitary controller. Contact your Trane sales office for information about other compatible zone sensors.

Discharge air temperature sensors

Discharge air temperature sensors must be Trane 10 kΩ (at 25°C) ther-mistors. The discharge air temperature (DAT) input may use a sealed temperature sensor (part number 4190 1100) or a duct/immersion tem-perature sensor (part number 4190 1103).

Damper actuators (optional)

Actuators cannot exceed 12 VA draw at 24 Vac. Use actuators with on/off action and spring return (to normally open or closed position), based on the desired default position.

Table 2. Trane zone temperature sensor options

BAS order number

ZoneTimed override

buttonsComm

jackSetpoint

thumbwheelTemperature

sensorOn Cancel

4190 1086 x x x

4190 1087 x

4190 1088 x x x x

4190 1089 x x

4190 1090 x x x x x

4190 1094 x x x

4190 7015(stainless steel wall plate)

x

6 CNT-SVX12C-EN

Chapter 2

Mounting the controller

This chapter gives recommendations and requirements for mounting the Tracer ZN517 unitary controller.

Location recommendationsFor rooftop and heat pump applications, the controller can be mounted inside the unit or at a convenient location inside the building. Trane recommends locating the Tracer ZN517 unitary controller:

• Near the controlled piece of equipment to reduce wiring costs• Where it is easily accessible for service personnel• Where public access is restricted to minimize the possibility of tam-

pering or vandalism

CNT-SVX12C-EN 7

Chapter 2 Mounting the controller

Mounting recommendationsMounting recommendations are as follows:

IMPORTANTMount the Tracer ZN517 unitary controller with the cover on to avoid

the possibility of damaging the circuit board during installation.

• Mount the controller in any direction, other than with the front of the cover facing downward.

• Mount using the two 3/16 in. (4.8 mm) radius mounting holes provided (see Figure 3). Mounting fasteners are not included.

• Attach the controller securely so it can withstand vibrations of associ-ated HVAC equipment.

• When the controller is mounted in a small enclosed compartment, complete all wiring connections before securing the controller in the compartment.

Figure 3. Mounting the Tracer ZN517 unitary controller

8 CNT-SVX12C-EN

Chapter 3

Applications for the

2-heat/2-cool configuration

This chapter provides information for wiring input and output terminals and setting DIP switches for typical 2-heat/2-cool applications. The func-tion of inputs and outputs is also defined for these applications.

The types of 2-heat/2-cool applications supported by the Tracer ZN517 unitary controller are:

• Rooftop units with or without economizers• Split systems with or without economizers

CNT-SVX12C-EN 9

Chapter 3 Applications for the 2-heat/2-cool configuration

Wiring requirements and optionsTable 3 shows required controller inputs for minimal proper operation of all 2-heat/2-cool applications.

Table 4 shows optional controller inputs and outputs for specific applications.

Figure 4 on page 11 shows a wiring diagram for the Tracer ZN517 that includes all required and all optional components for 2-heat/2-cool appli-cations.

Table 3. Required controller inputs for all 2-heat/2-cool applications

Function Input sourceFor more information,

see:

24 Vac power Terminals: GND, 24 V “AC power wiring” on page 85

Zone temperature Terminals: ZN, GNDor communicated

“ZN: Zone tempera-ture” on page 18

Table 4. Optional controller inputs and outputs for specific applications

Application Input/OutputFor more information,

see:

Economizing Input: DAT (discharge air temperature)

“Economizing” on page 23

Input: AI2 (outdoor air temperature)

Outputs: 24 V (24 Vac common) OPN (binary output)CLS (binary output)

Discharge air tempering*

Input: DAT “Discharge air tem-pering” on page 24

Demand control ventilation*

Input:AI1 (CO2 sensor)

“Demand control ventilation” on page 24

Cascade control Input: DAT “Cascade zone con-trol” on page 20

* In order to use this function, the economizing function must be enabled.

10 CNT-SVX12C-EN

Wiring requirements and options

Figure 4. Wiring diagram for 2-heat/2-cool applications

LEDA BBA +20GND-BI2- SET-BI1- ZNLED GNDPIN

ZONE SENSORZONE SENSOR

SERVICE

ANALOG INPUTSANALOG INPUTSCOMM5

COMM5

24VGND

HVAC UNITHVAC UNIT

RhRc 1G 432 5NO5COM

LED

STATUS5NC

BINARY INPUTSBINARY INPUTS

AI1 -DAT-

24VGND GND 24V OPN CLS

BINARY OUTPUTBINARY OUTPUTECONOMIZERAC OUTAC OUTAC POWERAC POWER

On

Cancel

5

4

3

2

1

+_

GND

-AI2-

LonTalk

Occupancyor generic(optional)

Typical 3-wire sensor

(optional)

Compressor 1 contactor

Heat stage 1

Tri-state modulating economizer (optional)

Fan

LonTalk

HN

24 VacGeneric binary output (optional)


G Y1 Y2

Heat stage 2

In

Out

(optional)Fan status(default: normally closedclosed = no flowopen = flow)or generic

Discharge air temperature

Power*

R W1 W2

Outdoor air temperature (optional)

*Terminals Rc and Rh are provided as inputs for 24 Vac power from the con-trolled device. If the device has a sepa-rate heating and cooling units, use Rh for heat and Rc for cooling. If com-bined, use only Rc (see “HVAC unit electrical circuit wiring” on page 82).

Dry contacts only

Common

CNT-SVX12C-EN 11


DIP switch settingsSet the DIP switches on the circuit board for the 2-heat/2-cool configura-tion. The correct settings are shown in Figure 5.

Figure 5. DIP switch settings for the 2-heat/2-cool configuration

1 2 3 4

O N D I P

1 2 3 4

O N D I P

1 2 3 4

O N D I P 2-heat/2-cool without economizer

2-heat/2-cool with economizer

12 CNT-SVX12C-EN

Binary outputs for 2-heat/2-cool applications

Binary outputs for 2-heat/2-cool

applicationsThis configuration supports rooftop units and split systems applications that have the following components:

• Economizer• Supply fan• Cool 1• Cool 2• Heat 1• Heat 2• Exhaust

The Tracer ZN517 controller has eight binary outputs. Each binary out-put is a relay with a rating of 12 VA. Table 5 describes the function of each output for 2-heat/2-cool applications.

Binary output 5

Use the Rover service tool to configure binary output 5 (5NO/5COM/5NC) in one of the following ways. It is the only output that can be configured as a generic binary output.

• Not used.• Exhaust fan: Will energize when the economizer outside air damper

position is greater than the user-defined control point.• Occupancy: Will energize when the Tracer ZN517 is in the occupied

mode.• Generic: Can be monitored only by a BAS and has no direct effect on

Tracer ZN517 operation.

Table 5. Binary outputs for 2-heat/2-cool applications

Binary output terminal label Function

OPN Economizer, drive open

CLS Economizer, drive closed

G Supply fan

1 (Y1) Cool stage 1

2 (Y2) Cool stage 2

3 (W1) Heat stage 1

4 (W2) Heat stage 2

5NO/5COM/5NC (binary output 5) Exhaust fan/occupancy/generic

CNT-SVX12C-EN 13


Overriding binary outputs

Use the manual output test to manually control the outputs in a defined sequence. For more information about the manual output test, see “Man-ual output test” on page 74.

Binary inputs for 2-heat/2-cool

applicationsThe Tracer ZN517 unitary controller has two binary inputs. Each binary input associates an input signal of 0 Vac with open contacts and 24 Vac with closed contacts. Table 6 gives the function of each binary input for 2 heat/2 cool applications. Each function is explained in the succeeding paragraphs. For an explanation of the diagnostics generated by each binary input, see “Table of diagnostics” on page 79. For more information about how the controller operates, see Chapter 4, “Sequence of operations for the 2-heat/2-cool configuration”.”

BI1: Occupancy or generic

The function of the occupancy input is to save energy by increasing the range of zone setpoints when the zone is unoccupied. BI1 is used for two occupancy-related functions. For stand-alone controllers, this binary input can be hard-wired to a binary switch, clock, or occupancy sensor to determine the occupancy mode—either occupied or unoccupied. For con-trollers receiving a BAS-communicated occupancy request, the function of BI1 is to change the mode from occupied to occupied standby. (For more information on occupancy-related functions, see “Occupancy modes” on page 20.) An occupancy sensor with a binary output may be used.

BI1 is the only input that can be configured as a generic binary input. When configured as a generic binary input, it can be monitored only by a BAS, and has no direct effect on Tracer ZN517 operation.

BI2: Fan status

The fan status input provides feedback to the controller regarding the fan’s operating status. If BI2 is wired to a fan status switch and the input indicates that the fan is not operating when the controller has the fan controlled to on, the controller will generate a Local Fan Switch Failure diagnostic. (For more information, see “Fan status” on page 25.)

Table 6. Binary inputs for 2-heat/2-cool applications

Binary input terminal label

Function

BI1 Occupancy or generic

BI2 Fan status

14 CNT-SVX12C-EN

Analog inputs for 2-heat/2-cool applications

Analog inputs for 2-heat/2-cool

applicationsThe Tracer ZN517 controller has five analog inputs. Table 7 describes the function of each input for 2-heat/2-cool applications. Each function is explained in the succeeding paragraphs. For an explanation of the diag-nostics generated by each analog input, see “Table of diagnostics” on page 79. For more information about how the controller operates, see Chapter 4, “Sequence of operations for the 2-heat/2-cool configuration”.

AI1: Universal 4–20 mA

The AI1 analog input can be configured in one of the three ways shown in Table 8.

If this input is not needed for an application, configure it as Not Used. This disables the generation of diagnostics.

For the generic input configuration, a 4–20 mA sensor must be hard-wired to the AI1 terminal. (Wiring is dependent on the specific applica-

Table 7. Analog inputs for 2-heat/2-cool applications

Analog input terminal label

Function

AI1 Universal analog input

AI2 Outdoor air temperature

DAT Discharge air temperature

ZN Zone temperature (required)

SET Temperature setpoint

Note:

Use a GND terminal as the common ground for all zone sensor analog inputs. See Figure 4 on page 11.

Table 8. AI1 configuration options and associated measurement ranges

Configuration Measurement range

Generic 4–20 mA input 0–100% (4 mA=0%; 20 mA=100%)

CO2 measurement 0–2000 ppm(4 mA=0 ppm; 20 mA=2000 ppm)

Relative humidity (RH) measurement 0–100%(4 mA=0% RH; 20 mA=100% RH)

Note:

AI1 is polarity sensitive.

CNT-SVX12C-EN 15


tion.) The sensor communicates a value of 0–100% to the BAS. This con-figuration has no direct effect on Tracer ZN517 operation.

For the CO2 measurement configuration, a 4–20 mA sensor must be hard-wired to the AI1 terminal as shown in Figure 6. The sensor will transmit a 0–2000 ppm value to the BAS. This configuration has no direct effect on Tracer ZN517 operation. If a valid value is established and then is no longer present, the controller generates a CO2 Sensor Failure diagnostic.

Figure 6. AI1 terminal wiring: CO2 measurement

For the RH measurement configuration, a hard-wired 4–20 mA zone humidity sensor (see Figure 7) must provide a value to the controller. If a valid hard-wired or communicated relative humidity value is established and then is no longer present, the controller generates an RH Sensor Fail-ure diagnostic and disables the dehumidification function. The RH sensor is used only to provide a valid humidity reading to a BAS; it does not affect the operation of the Tracer ZN517.

Figure 7. AI1 terminal wiring: RH measurement

+20GND AI1

Tracer ZN517

24 Vac

CO2 sensor(Trane part number:

4190 4100 or 4190 4101)

GNDOut24 Vac

+ –

+20GND AI1 Tracer ZN517

RH sensor

Figure Note:

The +20 terminal provides 20 ±2 Vdc that is used to power a Trane RH sensor (part numbers 4190 1109, 4190 7011, 4190 7012, 4190 7014).

16 CNT-SVX12C-EN

Analog inputs for 2-heat/2-cool applications

AI2: Outdoor air temperature or generic temperature

The AI2 analog input can functions as either:

• An outdoor air temperature input• A generic temperature input

If AI2 is configured as the local (hard-wired) outdoor air temperature input, the controller receives the temperature as a resistance signal from a 10 kΩ thermistor wired to analog input AI2. An outdoor air tempera-ture value communicated by means of a LonTalk link can also be used for controllers operating on a BAS. If both hard-wired and communicated outdoor air temperature values are present, the controller uses the com-municated value.

If you set DIP switch 3 to ON for economizing (see “DIP switch settings” on page 12), you automatically configure AI2 as an outdoor air tempera-ture input. Economizing (free cooling) is a function whereby outdoor air is used as a source of cooling before hydronic or DX cooling is used. The Tracer ZN517 uses the outdoor air temperature value to determine whether economizing is feasible. Economizing is not possible without a valid outdoor air temperature. (For more information, see “Economizing” on page 23.)

If AI2 is configured as a generic temperature input, it can be monitored by a BAS. The controller receives the temperature as a resistance signal from a 10 kΩ thermistor wired to analog input AI2. The generic tempera-ture input can be used with any Trane 10 kΩ thermistor. The thermistor can be placed in any location and has no effect on the operation of the con-troller. If you set DIP switch 3 to OFF (see “DIP switch settings” on page 12), you automatically configure AI2 as a generic temperature input.

DAT: Discharge air temperature

The DAT analog input functions as the local discharge air temperature input. The controller receives the temperature as a resistance signal from a 10 kΩ thermistor wired to analog input DAT. The thermistor is typically located downstream from all unit heating and cooling coils at the unit dis-charge area.

Trane recommends the use of a discharge air temperature sensor to uti-lize the cascade control function (see “Cascade zone control” on page 20). Cascade control is a more accurate method of temperature control. If no discharge air temperature sensor is used, the controller will default to control based solely on the zone temperature (see “Simplified zone con-trol” on page 20).

Note:

AI2 is not polarity sensitive; you can connect either terminal to either sensor lead.

Note:

DAT is not polarity sensitive; you can connect either terminal to either sensor lead.

CNT-SVX12C-EN 17


ZN: Zone temperature

The ZN analog input functions as the local (hard-wired) zone temperature input. The controller receives the temperature as a resistance signal from a 10 kΩ thermistor in a standard Trane zone sensor wired to analog input ZN. A communicated zone temperature value via the LonTalk communi-cations link can also be used for controllers operating on a BAS. When both a hard-wired and communicated zone temperature value is present, the controller uses the communicated value. If neither a hard-wired nor a communicated zone temperature value is present, the controller gener-ates a Space Temperature Failure diagnostic.

The ZN analog input is also used to communicate timed override requests and cancel requests to the controller for applications utilizing a Trane zone sensor with the ON and CANCEL button option.

SET: Temperature setpoint

The SET analog input functions as the local (hard-wired) temperature setpoint input for applications utilizing a Trane zone sensor with a tem-perature setpoint thumbwheel. Use the Rover service tool or a BAS to enable or disable the local setpoint input. A communicated setpoint value via the LonTalk communications link can also be used for controllers operating on a BAS. If both a hard-wired and a communicated setpoint value are present, the controller uses the communicated value. If neither a hard-wired nor a communicated setpoint value is present, the controller uses the stored default setpoints (configurable using the Rover service tool or a BAS). If a valid hard-wired or communicated setpoint value is established and then is no longer present, the controller generates a Local Space Setpoint Failure diagnostic.

18 CNT-SVX12C-EN

Chapter 4

Sequence of operations for the

2-heat/2-cool configuration

A Tracer ZN517 unitary controller configured to control a 2-heat/2-cool unit will operate to maintain the zone temperature setpoint. This chapter discusses many of the operational sequences the controller uses to accom-plish this goal.

Power-up sequenceWhen 24 Vac power is initially applied to the Tracer ZN517 unitary con-troller, the following sequence occurs:

1. The Status (green) LED goes on.

2. All outputs are controlled off.

3. The controller reads all input local values to determine initial values.

4. The power-up control wait function begins automatically if the config-ured power-up control wait time is greater than zero. When this func-tion is enabled, the controller waits for the configured amount of time (from 10 to 120 seconds) to allow a communicated occupancy request to arrive. If a communicated occupancy request arrives, normal oper-ation can begin. If a communicated occupancy request does not arrive, the controller assumes stand-alone operation.

5. The Status LED goes off.

6. The wait timer expires.

7. The Status LED goes on.

8. If a hard-wired zone-temperature value is not detected, the controller begins to wait for a communicated value. (This can take several min-utes [15-minute default] and occurs concurrently with the remainder of the power-up sequence.) If a communicated zone-temperature value arrives, normal operation can begin when the power-up sequence has concluded. If a communicated zone-temperature value does not arrive, the binary outputs remain off and a Space Tempera-ture Failure diagnostic is generated (normal operation cannot begin without a valid zone temperature value).

9. Normal operation begins assuming no diagnostics have been gener-ated.

CNT-SVX12C-EN 19

Chapter 4 Sequence of operations for the 2-heat/2-cool configuration

Cascade zone control Cascade zone control maintains zone temperature by controlling the dis-charge air temperature to control the zone temperature. The controller uses the difference between the measured zone temperature and the active zone temperature setpoint to produce a discharge air temperature setpoint. The controller compares the discharge air temperature setpoint with the discharge air temperature and calculates a unit heating/cooling capacity accordingly (see Figure 8). The end devices (outdoor air damper, valves, etc.) operate in sequence based on the unit heating/cooling capac-ity (0–100%).

Figure 8. Cascade zone control

If the discharge air temperature falls below the Discharge Air Control Point Low Limit (configurable using the Rover service tool) and cooling capacity is at a minimum, available heating capacity will be used to raise the discharge air temperature to the low limit (see “Discharge air temper-ing” on page 24).

Simplified zone control

In the absence of a discharge air temperature sensor, the controller uses simplified zone control to maintain the zone temperature. In the unoccu-pied mode, the controller maintains the zone temperature by calculating the required heating or cooling capacity (0–100%) according to the mea-sured zone temperature and the active zone temperature setpoint. The active zone temperature setpoint is determined by the current operating modes, which include occupancy and heat/cool modes.

Occupancy modesOccupancy modes can be controlled by any of the following:

• The state of the local (hard-wired) occupancy binary input BI1 (see “BI1: Occupancy or generic” on page 50)

• A timed override request from a Trane zone sensor (see “Timed over-ride control” on page 22)

Active zone temperature setpoint Difference

Calculated discharge air temperature setpoint

Calculated unit heating/cooling capacity

Measured zone

temperature

Measured discharge air temperature

Difference

20 CNT-SVX12C-EN

Occupancy modes

• A communicated signal from a peer device (see “Peer-to-peer commu-nication” on page 23)

• A communicated signal from a BAS

A communicated request, either from a BAS or a peer controller, takes precedence over local requests. If a communicated occupancy request has been established and is no longer present, the controller reverts to the default (occupied) occupancy mode after 15 minutes (if no hard-wired occupancy request exists). The Tracer ZN517 has the following occupancy mode options:

• Occupied• Unoccupied• Occupied standby• Occupied bypass

Occupied mode

In occupied mode, the controller maintains the zone temperature based on the occupied heating or cooling setpoints. The controller uses the occu-pied mode as a default when other modes of occupancy request are not present. The fan runs as configured (continuous or cycling). The outdoor air damper closes when the fan is off. The temperature setpoints can be local (hard-wired), communicated, or stored default values (configurable using the Rover service tool or a BAS).

Unoccupied mode

In unoccupied mode, the controller attempts to maintain the zone temper-ature based on the unoccupied heating or cooling setpoint. The fan cycles between high speed and off. The outdoor air damper remains closed. The controller always uses the stored default setpoint values (configurable using the Rover service tool or a BAS), regardless of the presence of a hard-wired or communicated setpoint value.

Occupied standby mode

The controller is placed in occupied standby mode only when a communi-cated occupied request is combined with an unoccupied request from occupancy binary input BI1. In occupied standby mode, the controller maintains the zone temperature based on the occupied standby heating or cooling setpoints. Because the occupied standby setpoints are typically spread 2°F (1.1°C) in either direction and the outdoor air damper is closed, this mode reduces the demand for heating and cooling the space. The fan runs as configured (continuous or cycling) for occupied mode. The controller always uses the stored default setpoint values (configurable using the Rover service tool or a BAS), regardless of hard-wired or com-municated setpoint values.

CNT-SVX12C-EN 21


Occupied bypass mode

The controller is placed in occupied bypass mode when the controller is operating in the unoccupied mode and either the timed override ON but-ton on the Trane zone sensor is pressed or the controller receives a com-municated occupied bypass signal from a BAS. In occupied bypass mode, the controller maintains the zone temperature based on the occupied heating or cooling setpoints. The fan runs as configured (continuous or cycling). The outdoor air damper closes when the fan is off. The controller will remain in occupied bypass mode until either the CANCEL button is pressed on the Trane zone sensor or the occupied bypass time (config-urable using the Rover service tool or a BAS) expires. The temperature setpoints can be local (hard-wired), communicated, or stored default val-ues (configurable using the Rover service tool or a BAS).

Timed override controlIf the zone sensor has a timed override option (ON/CANCEL buttons), pushing the ON button momentarily shorts the zone temperature signal to the controller. This short is interpreted as a timed override on request. A timed override on request changes the occupancy mode from unoccu-pied mode to occupied bypass mode. In occupied bypass mode, the control-ler controls the zone temperature based on the occupied heating or cooling setpoints. The occupied bypass time, which resides in the Tracer ZN517 and defines the duration of the override, is configurable (using the Rover service tool or a BAS) from 0 to 240 minutes (default value is 120 minutes). When the occupied bypass time expires, the unit changes from occupied bypass mode to unoccupied mode. Pushing the CANCEL button momentarily sends a fixed resistance of 1.5 kΩ to the ZN analog input of the controller, which is interpreted as a timed override cancel request. A timed override cancel request will end the timed override before the occupied bypass time has expired and will transition the unit from occupied bypass mode to unoccupied mode.

If the controller is in any mode other than unoccupied when the ON but-ton is pressed, the controller still starts the occupied bypass timer with-out changing the mode to occupied bypass. If the controller is placed in unoccupied mode before the occupied bypass timer expires, the controller will be placed in occupied bypass mode and remain in that mode until either the CANCEL button is pressed on the Trane zone sensor or the occupied bypass time expires.

Outdoor air damper operationThe Tracer ZN517 does not support a two-position outdoor air damper actuator. However, a modulating, triac, 3-wire floating point actuator with spring return can be used for two-position control. Two-position con-trol can function only when an outdoor air temperature (either hard-wired or communicated) does not exist, and by setting the damper mini-mum position (using the Rover service tool) to the desired value. To con-

22 CNT-SVX12C-EN

Fan operation

trol an air damper actuator for two-position control, configure the Tracer ZN517 for economizing (economizing will not function).

Fan operationThe Tracer ZN517 can be configured to run continuously at a single speed or to cycle on and off automatically. If configured for continuous opera-tion, the fan runs continuously during the occupied, occupied standby, and occupied bypass modes. If configured for cycling operation, the fan will cycle if the temperature is away from setpoint during the occupied, occupied standby, and occupied bypass modes. During the unoccupied mode, the fan cycles regardless of the fan configuration.

Peer-to-peer communicationTracer ZN517 unitary controllers have the ability to share data with other LonTalk-based controllers. Multiple controllers can be bound as peers, using the Rover service tool, to share:

• Setpoint• Zone temperature• Heating/cooling mode• Fan status• Unit capacity control

Shared data is communicated from one controller to any other controller that is bound to it as a peer. Applications having more than one unit serv-ing a single zone can benefit by using this feature; it allows multiple units to share a single zone temperature sensor and prevents multiple units from simultaneously heating and cooling.

EconomizingEconomizing (also referred to as “free cooling”) uses outside air for cool-ing. The Tracer ZN517 provides two triac (3-wire floating point) outputs to control the damper actuator. One output opens the actuator; the other closes it. The controller also provides analog inputs for both a discharge air temperature sensor and an outside air temperature sensor. While economizing is enabled, the controller uses a discharge air temperature (DAT) control loop to maintain proper temperature control. The controller opens the outside air damper, turns on the fan, and attempts to maintain a user-defined discharge air temperature. If the outside air is unsuitable for economizer operation, the outside air damper will close and normal operation (DX cooling) will be activated. Economizing plus DX cooling is initiated only when economizing alone cannot meet the zone’s cooling requirements.

To enable this function, set DIP switch 3 to ON (see “DIP switch settings” on page 12).

CNT-SVX12C-EN 23


Discharge air temperingDischarge air tempering (also called supply air tempering) prevents occu-pant discomfort caused by cold outside air being brought into a space through the outside air damper. This is an important feature in cold cli-mates because the outside air damper is never fully closed for ventilation purposes. Discharge air tempering starts when:

• The controller is in heating mode.• The space is otherwise satisfied (no heating or cooling required). • Ventilation air is passing through the unit• The discharge air temperature falls 10°F (5.6°C) below the occupied

heating setpoint.

Tempering stops when the occupied heating setpoint is exceeded. To enable this function, use the Rover service tool to select Supply Air Tem-pering Enabled.

Demand control ventilationThe Tracer ZN517 unitary controller modulates the outside air damper position in direct response to the CO2 level, regulating the amount of out-door air allowed to enter. This function is referred to as demand control ventilation. Demand control ventilation requires that the two triac (3-wire floating point) outputs be used to control the damper actuator. The minimum damper position will increase as CO2 levels rise above 500 ppm. The function executes with a 3-minute loop frequency to allow time for the sensor to respond.

To enable this function, use the Rover service tool to configure the Tracer ZN517 as follows:

• Configure AI1 as a carbon dioxide sensor• Enter a minimum CO2 level (Control Point)

(factory default: 500 ppm).• Enter a maximum CO2 threshold (Threshold)

(factory default: 1500 ppm).When the CO2 level reaches the threshold, the minimum position is 100% open.

Unit protection strategiesThe following strategies are initiated when specific conditions exist in order to protect the unit or building from damage:

• Filter maintenance timer• Fan off delay• Fan status

24 CNT-SVX12C-EN

Unit protection strategies

Filter-maintenance timer

The filter-maintenance timer tracks the amount of time (in hours) that the fan is enabled. The Maintenance Required Timer Setpoint (Maint Req Time Setpoint), configured with the Rover service tool, is used to set the amount of time until maintenance (typically, a filter change) is needed. If the setpoint is configured to zero, the filter-maintenance timer is dis-abled.

The controller compares the fan-run time to Maintenance Required Timer Setpoint. Once the setpoint is reached, the controller generates a Mainte-nance Required diagnostic. When the diagnostic is cleared, the controller resets the filter-maintenance timer to zero, and the timer begins accumu-lating fan-run time again.

Fan off delay

The fan stays on for an additional 30 seconds (adjustable with the Rover service tool) to allow the residual cooling or heating energy to be circu-lated through the system.

Fan status

The controller monitors fan status to protect equipment from overheat-ing. If fan or airflow is not detected for 30 seconds when needed, the equipment shuts down.

CNT-SVX12C-EN 25


26 CNT-SVX12C-EN

Chapter 5

Applications for the 4-cool

configuration

This chapter provides information for wiring input and output terminals and setting DIP switches for typical 4-cool applications. The function of inputs and outputs is also defined for these applications.

The types of 4-cool applications supported by the Tracer ZN517 unitary controller are rooftop units with or without economizers.

CNT-SVX12C-EN 27

Chapter 5 Applications for the 4-cool configuration

Wiring requirements and optionsTable 9 shows required controller inputs for minimal proper operation of all 4-cool applications.


Figure 9 on page 29 show typical applications that include all required and all optional components for 4-cool applications.

Table 9. Required controller inputs for all 4-cool applications


see:






see:












28 CNT-SVX12C-EN


Figure 9. Wiring diagram for 4-cool applications



SERVICE


COMM5

24VGND

HVAC UNITHVAC UNIT

RhRc 1G 432 5NO5COM

LED

STATUS5NC


AI1 -DAT-



On

Cancel

5

4

3

2

1

+_

GND

-AI2-

LonTalk

In


Discharge airtemperature

LonTalk

Out




Fan

HN

24 Vac

Generic binary output (optional)


G Y2


Power*

R Y3 Y4Y1


(optional)

Fan status or generic (optional)

Occupancy or generic (optional)


Dry contacts only

Common

CNT-SVX12C-EN 29


DIP switch settingsSet the DIP switches on the circuit board for the 4-cool configuration. The correct settings are shown in Figure 10.

Figure 10. DIP switch settings for the 4-cool configuration

1 2 3 4

O N D I P

1 2 3 4

O N D I P

1 2 3 4

O N D I P 4-cool without economizer

4-cool with economizer

30 CNT-SVX12C-EN

Binary outputs for 4-cool applications

Binary outputs for 4-cool applicationsThis configuration supports rooftop unit applications that have the fol-lowing components:

• Economizer• Supply fan• Cool 1• Cool 2• Cool 3• Cool 4• Exhaust fan

The Tracer ZN517 controller has seven binary outputs. Each binary out-put is a relay with a rating of 12 VA. Table 11 describes the function of each output for 4-cool applications.

Binary output 5








Table 11. Binary outputs for 4-cool applications




G Supply fan

1 (Y1) Cool stage 1

2 (Y2) Cool stage 2

3 (Y3) Cool stage 3

4 (Y4) Cool stage 4

5NO/5COM/5NC (binary output 5) Exhaust fan/generic/occupancy

CNT-SVX12C-EN 31


Binary inputs for 4-cool applicationsThe Tracer ZN517 unitary controller has two binary inputs. Each binary input associates an input signal of 0 Vac with open contacts and 24 Vac with closed contacts. Table 12 gives the function of each binary input for 4-cool applications. Each function is explained in the succeeding para-graphs. For an explanation of the diagnostics generated by each binary input, see “Table of diagnostics” on page 79. For more information about how the controller operates, see Chapter 6, “Sequence of operations for the 4-cool configuration”.”


The function of the occupancy input is to save energy by increasing the range of zone setpoints when the zone is unoccupied. BI1 is used for two occupancy-related functions. For stand-alone controllers, this binary input can be hard-wired to a binary switch, clock, or occupancy sensor to determine the occupancy mode—either occupied or unoccupied. For con-trollers receiving a BAS-communicated occupancy request, the function of BI1 is to change the mode from occupied to occupied standby. (For more information on occupancy-related functions, see “Occupancy modes” on page 38.)


BI2: Fan status


Table 12. Binary inputs for 4-cool applications


Function


BI2 Fan status

32 CNT-SVX12C-EN

Analog inputs for 4-cool applications

Analog inputs for 4-cool applicationsThe Tracer ZN517 controller has five analog inputs. Table 13 describes the function of each input for 4-cool applications. Each function is explained in the succeeding paragraphs. For an explanation of the diag-nostics generated by each analog input, see “Table of diagnostics” on page 79. For more information about how the controller operates, see Chapter 6, “Sequence of operations for the 4-cool configuration”.




For the generic input configuration, a 4–20 mA sensor must be hard-wired to the AI1 terminal. (Wiring is dependent on the specific applica-tion.) The sensor communicates a value of 0–100% to the BAS. This con-figuration has no direct effect on Tracer ZN517 operation.

Table 13. Analog inputs for 4-cool applications


Function






Note:







Note:


CNT-SVX12C-EN 33


For the CO2 measurement configuration, a 4–20 mA sensor must be hard-wired to the AI1 terminal as shown in Figure 11 on page 34. The sensor will transmit a 0–2000 ppm value to the BAS. This configuration has no direct effect on Tracer ZN517 operation. If a valid value is established and then is no longer present, the controller generates a CO2 Sensor Fail-ure diagnostic.


For the RH measurement configuration, a hard-wired 4–20 mA zone humidity sensor (see Figure 12) must provide a value to the controller. If a valid hard-wired or communicated relative humidity value is estab-lished and then is no longer present, the controller generates an RH Sen-sor Failure diagnostic and disables the dehumidification function. The RH sensor is used only to provide a valid humidity reading to a BAS; it does not affect the operation of the Tracer ZN517.


+20GND AI1

Tracer ZN517

24 Vac


4190 4100 or 4190 4101)

+ –

+20GND AI1 Tracer ZN517

RH sensor

Figure Note:


GNDOut24 Vac

34 CNT-SVX12C-EN

Analog inputs for 4-cool applications


The AI2 analog input can function as either:








Note:


Note:


CNT-SVX12C-EN 35







36 CNT-SVX12C-EN

Chapter 6

Sequence of operations for

the 4-cool configuration

A Tracer ZN517 unitary controller configured to control a 4-cool unit will operate to maintain the zone temperature setpoint. This chapter dis-cusses many of the operational sequences the controller uses to accom-plish this goal.











CNT-SVX12C-EN 37

Chapter 6 Sequence of operations for the 4-cool configuration

Cascade zone control Cascade zone control maintains zone temperature by controlling the dis-charge air temperature to control the zone temperature. The controller uses the difference between the measured zone temperature and the active zone temperature setpoint to produce a discharge air temperature setpoint. The controller compares the discharge air temperature setpoint with the discharge air temperature and calculates a unit heating/cooling capacity accordingly (see Figure 13). The end devices (outdoor air damper, valves, etc.) operate in sequence based on the unit heating/cooling capac-ity (0–100%).











Measured zone

temperature


Difference

38 CNT-SVX12C-EN

Occupancy modes





Occupied mode

In occupied mode, the controller maintains the zone temperature based on the occupied heating or cooling setpoints. The controller uses the occu-pied mode as a default when other modes of occupancy request are not present. The fan runs as configured (continuous or cycling). The outdoor air damper closes when the fan is off. The temperature setpoints can be local (hard-wired), communicated, or stored default values (configurable using the Rover service tool or a BAS).

Unoccupied mode

In unoccupied mode, the controller attempts to maintain the zone temper-ature based on the unoccupied heating or cooling setpoint. The fan cycles between high speed and off. The outdoor air damper remains closed. The controller always uses the stored default setpoint values (configurable using the Rover service tool or a BAS), regardless of the presence of a hard-wired or communicated setpoint value.


The controller is placed in occupied standby mode only when a communi-cated occupied request is combined with an unoccupied request from occupancy binary input BI1. In occupied standby mode, the controller maintains the zone temperature based on the occupied standby heating or cooling setpoints. Because the occupied standby setpoints are typically spread 2°F (1.1°C) in either direction and the outdoor air damper is closed, this mode reduces the demand for heating and cooling the space. The fan runs as configured (continuous or cycling) for occupied mode.

CNT-SVX12C-EN 39



The controller is placed in occupied bypass mode when the controller is operating in the unoccupied mode and either the timed override ON but-ton on the Trane zone sensor is pressed or the controller receives a com-municated occupied bypass signal from a BAS. In occupied bypass mode, the controller maintains the zone temperature based on the occupied heating or cooling setpoints. The fan runs as configured (continuous or cycling). The outdoor air damper closes when the fan is off. The controller will remain in occupied bypass mode until either the CANCEL button is pressed on the Trane zone sensor or the occupied bypass time (config-urable using the Rover service tool or a BAS) expires. The temperature setpoints can be local (hard-wired), communicated, or stored default val-ues (configurable using the Rover service tool or a BAS).

Timed override controlIf the zone sensor has a timed override option (ON/CANCEL buttons), pushing the ON button momentarily shorts the zone temperature signal to the controller. This short is interpreted as a timed override on request. A timed override on request changes the occupancy mode from unoccu-pied mode to occupied bypass mode. In occupied bypass mode, the control-ler controls the zone temperature based on the occupied heating or cooling setpoints. The occupied bypass time, which resides in the Tracer ZN517 and defines the duration of the override, is configurable (using the Rover service tool or a BAS) from 0 to 240 minutes (default value is 120 minutes). When the occupied bypass time expires, the unit changes from occupied bypass mode to unoccupied mode. Pushing the CANCEL button momentarily sends a fixed resistance of 1.5 kΩ to the ZN analog input of the controller, which is interpreted as a timed override cancel request. A timed override cancel request will end the timed override before the occu-pied bypass time has expired and will transition the unit from occupied bypass mode to unoccupied mode.



40 CNT-SVX12C-EN

Fan operation








CNT-SVX12C-EN 41




heating setpoint.


Demand control ventilationThe Tracer ZN517 unitary controller modulates the outside air damper position in direct response to the CO2 level, regulating the amount of out-door air allowed to enter. This function is referred to as demand control ventilation. Demand control ventilation requires that the two triac (3-wire floating point) outputs be used to control the damper actuator. The minimum damper position will increase as CO2 levels rise above 500 ppm. The function executes with a 3-minute loop time to allow time for the sensor to respond.






• Filter maintenance timer• Fan off delay• Fan status

42 CNT-SVX12C-EN

Unit protection strategies




Fan off delay

The fan stays on for an additional 30 seconds (adjustable with the Rover service tool) to allow the residual cooling energy to be circulated through the system.

Fan status


CNT-SVX12C-EN 43


44 CNT-SVX12C-EN

Chapter 7

Applications for the heat

pump configuration

This chapter provides information for wiring input and output terminals and setting DIP switches for typical heat pump applications. The function of inputs and outputs is also defined for these applications.

The types of heat pump applications supported by the Tracer ZN517 uni-tary controller are heat pumps with:

• One or two compressors with reversing valves• Optional auxiliary heat control• Optional economizer control

CNT-SVX12C-EN 45

Chapter 7 Applications for the heat pump configuration

Wiring requirements and optionsTable 15 shows required controller inputs for minimal proper operation of all heat pump applications.


Figure 14 on page 47 shows all required and optional components con-nected for heat pump applications.

Table 15. Required controller inputs for proper operation


see:






see:












46 CNT-SVX12C-EN


Figure 14. Wiring diagram for heat pump applications



SERVICE


COMM5

24VGND

HVAC UNITHVAC UNIT

RhRc 1G 432 5NO5COM

LED

STATUS5NC


AI1 -DAT-



On

Cancel

5

4

3

2

1

+_

GND

-AI2-

LonTalk

In

Out

Occupancy or generic (optional)


Reversing valve


Fan

HN

24 Vac

Generic binary output (optional)


G

Auxiliary heat

Power*

R O W1Y1 Y2

Discharge airtemperature LonTalk


(optional)

Fan status or generic (optional)



Dry contacts only

Common

CNT-SVX12C-EN 47


DIP switch settingsSet the DIP switches on the circuit board for the heat pump configura-tion. The correct settings are shown in Figure 15.

Figure 15. DIP switch settings for heat pump configuration

1 2 3 4

O N D I P

1 2 3 4

O N D I P

1 2 3 4

O N D I P Heat pumpwithout economizer

Heat pump with economizer

48 CNT-SVX12C-EN

Binary outputs for heat pump applications

Binary outputs for heat pump

applicationsThis configuration supports heat pump applications that have the follow-ing components:

• Economizer• Supply fan• One or two compressors• Reversing valve• Auxiliary heat• Exhaust fan

The Tracer ZN517 controller has eight binary outputs. Each binary out-put is a relay with a rating of 12 VA. Table 17 describes the function of each output for heat pump applications.

Binary output 5








Table 17. Binary outputs for 2-heat/2-cool applications




G Supply fan

1 (Y1) Compressor 1

2 (Y2) Compressor 2

3 (O) Reversing valve

4 (W1) Auxiliary heat

5NO/5COM/5NC (binary output 5) Exhaust fan/generic/occupancy

CNT-SVX12C-EN 49


Binary inputs for heat pump

applicationsThe Tracer ZN517 unitary controller has two binary inputs. Each binary input associates an input signal of 0 Vac with open contacts and 24 Vac with closed contacts. Table 18 gives the function of each binary input for 4-cool applications. Each function is explained in the succeeding para-graphs. For an explanation of the diagnostics generated by each binary input, see “Table of diagnostics” on page 79. For more information about how the controller operates, see Chapter 8, “Sequence of operations for the heat pump configuration”.”


The function of the occupancy input is to save energy by increasing the range of zone setpoints when the zone is unoccupied. BI1 is used for two occupancy-related functions. For stand-alone controllers, this binary input can be hard-wired to a binary switch, clock, or occupancy sensor to determine the occupancy mode—either occupied or unoccupied. For con-trollers receiving a BAS-communicated occupancy request, the function of BI1 is to change the mode from occupied to occupied standby. (For more information on occupancy-related functions, see “Occupancy modes” on page 56.)


BI2: Fan status


Table 18. Binary inputs for heat pump applications


Function


BI2 Fan status

50 CNT-SVX12C-EN

Analog inputs for heat pump applications

Analog inputs for heat pump

applicationsThe Tracer ZN517 controller has five analog inputs. Table 19 describes the function of each input for heat pump applications. Each function is explained in the succeeding paragraphs. For an explanation of the diag-nostics generated by each analog input, see “Table of diagnostics” on page 79. For more information about how the controller operates, see Chapter 8, “Sequence of operations for the heat pump configuration”.




For the generic input configuration, a 4–20 mA sensor must be hard-wired to the AI1 terminal. (Wiring is dependent on the specific applica-

Table 19. Analog inputs for heat pump applications


Function






Note:







Note:


CNT-SVX12C-EN 51


tion.) The sensor communicates a value of 0–100% to the BAS. This con-figuration has no direct effect on Tracer ZN517 operation.

For the CO2 measurement configuration, a 4–20 mA sensor must be hard-wired to the AI1 terminal as shown in Figure 16. The sensor will transmit a 0–2000 ppm value to the BAS. This configuration has no direct effect on Tracer ZN517 operation. If a valid value is established and then is no longer present, the controller generates a CO2 Sensor Failure diagnostic.


For the RH measurement configuration, a hard-wired 4–20 mA zone humidity sensor (see Figure 17) must provide a value to the controller. If a valid hard-wired or communicated relative humidity value is estab-lished and then is no longer present, the controller generates a RH Sensor Failure diagnostic and disables the dehumidification function. The RH sensor is used only to provide a valid humidity reading to a BAS; it does not affect the operation of the Tracer ZN517.


+20GND AI1

Tracer ZN517

24 Vac

GNDOut24 Vac


4190 4100 or 4190 4101)

+ –

+20GND AI1Tracer ZN517

RH sensor

Figure Note:


52 CNT-SVX12C-EN

Analog inputs for heat pump applications


The AI2 analog input can function as either:








Note:


Note:


CNT-SVX12C-EN 53







54 CNT-SVX12C-EN

Chapter 8

Sequence of operations for

the heat pump configuration

A Tracer ZN517 unitary controller configured to control a heat pump will operate to maintain the zone temperature setpoint. This chapter dis-cusses many of the operational sequences used to accomplish this goal.











CNT-SVX12C-EN 55

Chapter 8 Sequence of operations for the heat pump configuration

Cascade zone controlCascade zone control maintains zone temperature by controlling the dis-charge air temperature to control the zone temperature. The controller uses the difference between the measured zone temperature and the active zone temperature setpoint to produce a discharge air temperature setpoint. The controller compares the discharge air temperature setpoint with the discharge air temperature and calculates a unit heating/cooling capacity accordingly (see Figure 18). The end devices (outdoor air damper, valves, etc.) operate in sequence based on the unit heating/cooling capac-ity (0–100%).











Measured zone

temperature


Difference

56 CNT-SVX12C-EN

Occupancy modes





Occupied mode

In occupied mode, the controller maintains the zone temperature based on the occupied heating or cooling setpoints. The controller uses the occu-pied mode as a default when other modes of occupancy request are not present. The fan runs as configured (continuous or cycling with compres-sor operation). The outdoor air damper closes when the fan is off. The temperature setpoints can be local (hard-wired), communicated, or stored default values (configurable using the Rover service tool or a BAS).

Unoccupied mode

In unoccupied mode, the controller operates to maintain the zone temper-ature based on the unoccupied heating or cooling setpoint. The fan cycles with compressor operation. The outdoor air damper remains closed. The controller always uses the stored default setpoint values (configurable using the Rover service tool or a BAS), regardless of the presence of a hard-wired or communicated setpoint value.


The controller is placed in occupied standby mode only when a communi-cated occupied request is combined with an unoccupied request from occupancy binary input BI1. In occupied standby mode, the controller maintains the zone temperature based on the occupied standby heating or cooling setpoints. Because the occupied standby setpoints are typically spread 2°F (1.1°C) in either direction and the outdoor air damper is closed, this mode reduces the demand for heating and cooling the space. The fan runs as configured (continuous or cycling with the compressor).

CNT-SVX12C-EN 57



The controller is placed in occupied bypass mode when the controller is operating in the unoccupied mode and either the timed override ON but-ton on the Trane zone sensor is pressed or the controller receives a com-municated occupied bypass signal from a BAS. In occupied bypass mode, the controller maintains the zone temperature based on the occupied heating or cooling setpoints. The fan runs as configured (continuous or cycling with the compressor). The outdoor air damper closes when the fan is off. The controller will remain in occupied bypass mode until either the CANCEL button is pressed on the Trane zone sensor or the occupied bypass time (configurable using the Rover service tool or a BAS) expires. The temperature setpoints can be local (hard-wired), communicated, or stored default values (configurable using the Rover service tool or a BAS).

Timed override controlIf the zone sensor has a timed override option (ON/CANCEL buttons), pushing the ON button momentarily shorts the zone temperature signal to the controller. This short is interpreted as a timed override on request. A timed override on request changes the occupancy mode from unoccu-pied mode to occupied bypass mode. In occupied bypass mode, the control-ler controls the zone temperature based on the occupied heating or cooling setpoints. The occupied bypass time, which resides in the Tracer ZN517 and defines the duration of the override, is configurable (using the Rover service tool or a BAS) from 0 to 240 minutes (default value is 120 minutes). When the occupied bypass time expires, the unit changes from occupied bypass mode to unoccupied mode. Pushing the CANCEL button momentarily sends a fixed resistance of 1.5 kΩ to the ZN analog input of the controller, which is interpreted as a timed override cancel request. A timed override cancel request will end the timed override before the occu-pied bypass time has expired and will transition the unit from occupied bypass mode to unoccupied mode.



58 CNT-SVX12C-EN

Heating or cooling mode


Heating or cooling modeThe heating or cooling mode can be determined in one of two ways:

• By a communicated signal from a BAS or a peer controller• Automatically, as determined by the controller

A communicated heating signal permits the controller to heat only. A communicated cooling signal permits the controller to cool only. A com-municated auto signal allows the controller to automatically change from heating to cooling and vice versa.

In heating and cooling mode, the controller maintains the zone tempera-ture based on the active heating setpoint and the active cooling setpoint, respectively. The active heating and cooling setpoints are determined by the occupancy mode of the controller.

When no communicated signal is present (stand-alone operation) or the communicated signal is auto, the controller automatically determines the heating or cooling mode.


Compressor operationThe Tracer ZN517 supports heat pump applications with one or two com-pressors. The compressor(s) will cycle to meet zone temperature require-ments. Compressor operation will be overridden by a preset 3-minute minimum on/off time delay in order to maintain oil return when the unit is either initially energized, manually reset, switched between modes, or cycled within a single mode.

Reversing valve operationThe reversing valve is configurable to energize in either the cooling mode (typical of Trane units) or the heating mode. Be sure to configure the reversing valve operation based on the heat pump manufacturer’s design. An energized valve will remain energized until a mode change (either

CNT-SVX12C-EN 59


from cooling to heating or vice versa) is initiated. The reversing-valve operation is delayed after compressor shutdown to reduce noise due to refrigerant migration. The reversing valve will de-energize when a power failure occurs, or when the controller is set to off either through a commu-nicated off signal or when the fan switch is set to OFF.





heating setpoint.


Demand control ventilationThe Tracer ZN517 unitary controller modulates the outside air damper position in direct response to the CO2 level, regulating the amount of out-door air allowed to enter. This function is referred to as demand control ventilation. Demand control ventilation requires that the two triac (3-

60 CNT-SVX12C-EN

Peer-to-peer communication

wire floating point) outputs be used to control the damper actuator. The minimum damper position will increase as CO2 levels rise above 500 ppm. The function executes with a 3-minute loop frequency to allow time for the sensor to respond.









• Filter-maintenance timer• Fan off delay• Fan status



CNT-SVX12C-EN 61



Fan off delay

The fan stays on for an additional 30 seconds (adjustable with the Rover service tool) to allow the residual cooling or heating energy to be circu-lated through the system.

Fan status


62 CNT-SVX12C-EN

Chapter 9

PID control

This chapter will help you set up, tune, and troubleshoot proportional, integral, derivative (PID) control loops used in the Tracer ZN517 unitary controller. For more information about PID loops, see BAS-APG002, PID Control in Tracer Multi-Purpose Controllers.

PID control requires the use of a Rover service tool. All PID factory defaults can be restored by clicking the Use Defaults button.

What PID loops doA PID loop automatically controls an output to maintain a measured value at its setpoint by monitoring the error (the difference between the measured value and the setpoint). The loop performs proportional, inte-gral, and derivative calculations to determine how aggressively to change the output.

The goal of PID control is to reach the setpoint as quickly as possible without overshooting the setpoint or destabilizing the system and to maintain the setpoint consistently over time. If the system is too aggres-sive, it will overshoot the setpoint as shown in Figure 19. If it is not aggressive enough, the time to reach the setpoint will be unacceptably slow.

Figure 19. The effects of PID aggressiveness

Setpoint

Initial point

Too aggressive (overshoot)

Too slow

Time

Ideal response

Mea

sure

d va

lue

CNT-SVX12C-EN 63

Chapter 9 PID control

PID calculationsPID algorithms perform three calculations: the proportional calculation, the integral calculation, and the derivative calculation. These calcula-tions are independent of each other but are combined to determine the response of the controller to the error.

Proportional calculation

The proportional calculation responds to how far the measured value is from the setpoint. The larger the error, the larger the output of the calcu-lation. The proportional calculation has a much stronger effect on the result of the PID algorithm than either the integral or derivative calcula-tions. It determines the responsiveness (or aggressiveness) of a control system. Though some systems use only proportional control, most Trane controllers use a combination of proportional and integral control.

Proportional-only control loops require an error to produce an output. If the setpoint and the process variable are the same, the error is zero, so the system does not have an output. In an HVAC system, this can cause an actuator to open or close. The integral calculation solves this problem.

The recommended range for the proportional calculation in the Tracer ZN517 is 4–16. Restore PID factory defaults by clicking the Use Defaults button.

Integral calculation

The integral calculation responds to the length of time the measured value is not at setpoint. The longer the measured value is not at setpoint, the larger the output of the calculation.

The integral calculation uses the sum of past errors to maintain an out-put when the error is zero. Line 1 in Figure 20 on page 65 shows that with proportional-only control, when the error becomes zero, the PID output also goes to zero. Line 2 in Figure 20 shows the integral output added to the proportional output. Because the integral calculation is the sum of past errors, the output remains steady rather than dropping to zero when the error is zero. The benefit of this is that the integral calculation keeps the output at the appropriate level to maintain an error of zero.

The value of the integral calculation can build up over time (because it is the sum of all past errors), and this built-up value must be overcome before the system can change direction. This prevents the system from over-reacting to minor changes, but can potentially slow the system down.

The recommended range for the integral calculation in the Tracer ZN517 is 1–10. Restore PID factory defaults by clicking the Use Defaults button.

64 CNT-SVX12C-EN

Sampling frequency

Figure 20. Integral output added to proportional output

Derivative calculation

The derivative calculation responds to the change in error. In other words, it responds to how quickly the measured value is approaching set-point. The derivative calculation can be used to smooth an actuator motion or cause an actuator to react faster.

However, derivative control has several disadvantages:

• It can react to noise in the input signal. • Setting derivative control requires balancing between two extremes;

too much derivative gain and the system becomes unstable, too little and the derivative gain has almost no effect.

• The lag in derivative control makes tuning difficult. • Large error deadbands, common in HVAC applications, render deriv-

ative control ineffective.

Because of these disadvantages, derivative control is rarely used in HVAC applications (with the exception of steam valve controllers, which use derivative control to force the steam valve to react faster to changes).

Sampling frequencyThe sampling frequency is the rate at which the input signal is sampled and PID calculations are performed. Using the right sampling frequency is vital to achieving a responsive and stable system. Problems can arise if the sampling frequency is too slow or too fast in comparison to time lags in the system.

Sampling too slowly can cause an effect called aliasing in which not enough data is sampled to form an accurate picture of changes in the

Out

put

Time

Error ≠ 0 Error = 0

Proportional + integral output

Proportional + integral output if proportional output has gone to zero

1

2

Proportional-only output

CNT-SVX12C-EN 65


measured value. The system may miss important information and reach setpoint slowly or not at all.

Figure 21 and Figure 22 show how aliasing can affect system response. In Figure 21 the sampling frequency is too slow. Because of this, many of the actual changes in duct static pressure are missed. In Figure 22 the sam-pling frequency is fast enough that the changes in static pressure are tracked accurately.

Figure 21. Sampling too slowly

Figure 22. Sampling at the correct rate

Problems also arise from sampling too quickly. Some systems have natu-rally slow response times, such as when measuring room temperature. Slow response times can also be caused by equipment lags. Since PID loops respond to error and changes in error over time, if the process vari-able (measured value) changes slowly, then the error will remain constant for an extended period of time. If the process variable is sampled repeat-edly during this time, the proportional output remains about the same, but the integral output becomes larger (because it is the sum of past errors). When the control system does respond, the response is out of pro-portion to the reality of the situation, which can destabilize the system.

Sampling points Changes missed by system

Time

Duc

t st

atic

pre

ssur

e

Time

Duc

t st

atic

pre

ssur

e

Sampling points

66 CNT-SVX12C-EN

Sampling frequency

The control system should always wait to process the result of a change before making another change.

Figure 23 shows the process variable if sampling times are too fast, acceptable, and barely acceptable. If the sampling frequency is too fast (2 seconds), the process variable begins to oscillate and finally destabilizes because the PID loop output drives the actuator to extremes.

Figure 23. System stability with different sampling times

Sampling freq. = 10 s Sampling freq. = 20 s

Sampling freq. = 2 s(system destabilizes if sampling freq. is too fast)

Time

Proc

ess

varia

ble

CNT-SVX12C-EN 67


PID loop actionThe action of a PID loop determines how it reacts to a change in the pro-cess variable (such as a room temperature). A controller using direct action increases the output when the process variable increases. A con-troller using reverse action decreases the output when the process vari-able increases.

Direct action

Figure 24 shows the temperature when a system is cooling a space. If the error is large and the PID output is at 100%, the actuator and valve com-bination are fully open. As the process variable (room temperature) decreases, the error becomes smaller, and the controller closes the valve to reduce or stop cooling. Since the PID output and process variable move in the same direction (both decreasing), the loop is direct acting.

Figure 24. Cooling a space

Reverse action

Figure 25 shows the temperature when a system is heating a space. If the error is large and the PID output is at 100%, the actuator and valve com-bination are fully open. If the process variable (room temperature) increases, reducing the error, the controller closes the valve to reduce heating. Since the PID output and process variable move in opposite directions, the loop is reverse acting.

Figure 25. Heating a space

Error

Process variable (temperature)

Setpoint

Time

Tem

pera

ture

Error

Setpoint

Tem

pera

ture

Time

Process variable (temperature)

68 CNT-SVX12C-EN

Error deadband

Error deadbandError deadband is typically used to minimize actuator activity. It can also be used to allow for some “slop” in the system sensors and actuator mechanics. Error deadband prevents the PID output from changing if the absolute value of the error is less than the error deadband. For example, in Figure 26 the error deadband is set at 2.0°F (1.1°C). As long as the absolute value of the error is less than the 2.0°F (1.1°C), the PID output cannot change. If the absolute value of the error does exceed 2.0°F (1.1°C), the PID output can change.

Figure 26. Error deadband

As can be seen from Figure 26, error deadband is a means of limiting how often an actuator is controlled. If a PID loop controls a chilled water valve, this is not so important. But if a PID loop controls how many stages of cooling are being used, it is important to limit equipment cycling.

Adjusting error deadband for modulating outputs

In most applications, start with an error deadband of five or ten times the sensor resolution. For example, thermistors have a resolution of approxi-mately 0.1°F (0.06°C), so a good error deadband is 0.5°F (0.3°C). This set-ting ensures that the sensor reading has changed an adequate amount before the controller responds.

IMPORTANTThe error deadband should not be smaller than the sensor resolution or

the controller will react to noise.

Adjusting error deadband for staged outputs

This section shows how to adjust the error deadband for staging applica-tions.

Finding the best error deadband for staged output applications is more difficult than for modulating outputs. Instead of using a continuous actu-ator, such as a chilled water valve, staged systems use binary outputs to start and stop pieces of equipment, such as fans in a cooling tower. Each

Control

ControlSetpoint

Process variable

Error deadband

Err

or

CNT-SVX12C-EN 69


piece of equipment contributes a set amount to the final output. When setting the error deadband for staged outputs, the main goal is to reduce equipment cycling.

Follow these guidelines when adjusting the error deadband:

• Ask how tight control should be. A smaller error deadband results in tighter control, but control should not be so tight that the stages cycle on and off too frequently.For example, for a VAV air-handler turning on cooling stages, control can be somewhat loose. The individual VAV boxes control their valve to the space depending on the supply air temperature. If the supply air temperature is relatively warm, the VAV box allows more air flow. If the supply air temperature is somewhat cool, the VAV box con-stricts the air flow.

• The contribution of each stage can change depending on external cir-cumstances, so make adjustments under worst case conditions. Adjust the error deadband for cooling tower fan stages on very warm days, and adjust the error deadband for boiler stages on very cold days.

With the preceding guidelines in mind, use the following procedure to determine error deadband.

To adjust the error deadband for staged outputs:

1. Run the system manually.

If possible, do so under worst-case conditions for the site. Although it is not always possible for a technician to do this, it is possible for a well-trained customer.

2. Find the smallest change in temperature, ∆T, that the first stage can contribute (the quantity could also be building static pressure for fans or flow for pumps).

Pay attention to possible changes in external circumstances, such as the amount of water flow. If the system uses a lead-lag approach to the equipment, it will be necessary to find the minimum ∆T for all stages.

3. Multiply ∆T by 0.45 (the error deadband should be slightly less than half of ∆T).

Keep in mind the resolution of the sensor. You may need to round the error deadband to a more reasonable value.

4. Run the system with the new error deadband.

Cycling should be reduced as much as possible.

70 CNT-SVX12C-EN

Other PID settings

Other PID settingsYou can also use these settings to manage PID loops:

• Proportional bias, which takes the place of derivative gain in propor-tional-only control

• Minimum and maximum output, which limit the range of output of the PID algorithm

• Enabled and disabled modes, which enable the PID output or disable it to a default value

• Fail-safe mode sets the PID output to a “safe” value if the hardware input that provides the process variable fails.

For more information, see BAS-APG002, PID Control in Tracer Multi-Purpose Controllers.

Troubleshooting procedure

IMPORTANTRemember to change only one thing at a time.

Follow these steps to troubleshoot a PID loop:

1. Make sure that the system is not in override.

2. Graph the process variable, setpoint, and valve position over time to determine how the system performs.

Look at the big picture. Can the system do what’s expected of it? What is happening to the process variable? Is it oscillating or failing to reach setpoint? Is the output oscillating?

3. Check for failure conditions that are always true.

4. Check PID settings for:

• Output minimum incorrectly set to 100%• Output maximum incorrectly set to 0%• Sampling time that is too fast or too slow

5. Check the system for disturbances from:

• Bad actuator linkages• Faulty sensors

6. Change PID gains.

• Reduce gains if experiencing system overshoot, output at mini-mum or maximum, or cycling of output around setpoint

• Increase gains if experiencing system undershoot

CNT-SVX12C-EN 71


Tips for specific problemsTable 21 provides tips for troubleshooting specific problems.

Changing the sampling frequency

The major cause of actuator cycling is time lags in the system. If a 10% change in PID output requires two minutes to affect the process variable, it does no good to have the sampling frequency set to two seconds. The integral contribution will build up before any significant change in error can be measured. A sampling frequency of 30 to 60 seconds would work much better in this situation. In other words, to fix a cycling system, slow down the loop! See “Sampling frequency” on page 65 for more informa-tion.

Changing the gains

Be careful when changing PID gains. Never change gains unless the effects can be measured. Use a doubling/halving technique when increas-ing or decreasing gains. If the PID gains are set to 4, 1, and 0 respectively, and you are going to reduce them, try 2, 0.5, and 0. If the system now undershoots, try gains of 3, 0.75, and 0 respectively.

Table 21. Tips for specific problems

Problem Tips

Measured value is cycling around setpoint

• Slow the sampling frequency• Decrease PID gains

Overshooting setpoint Reduce gains

Undershooting setpoint Increase gains

Output at maximum Ensure that minimum output is not set to 100%

Output at minimum Ensure that maximum output is not set to 0%

72 CNT-SVX12C-EN

Chapter 10

Status indicators for

operation and

communication

This chapter describes the operation and communication status indica-tors on the Tracer ZN517 unitary controller, including:

• A description of the location and function of the Test button and Ser-vice Pin button and the light-emitting diodes (LEDs)

• A complete list of the diagnostics that can occur, their effect on con-troller outputs, and an explanation of how to clear diagnostics and restore the device to normal operation

Test buttonUse the Test button to perform the manual output test (see “Manual out-put test” on page 74), which verifies that the controller is operating prop-erly. Figure 27 shows its location.

Figure 27. Tracer ZN517 unitary controller circuit board

J1 (location of jumper for Rc, Rh terminals)

LonTalk LED (yellow)

Status LED (green)

Test button

Service Pin button

DIP switches

Service LED (red)

CNT-SVX12C-EN 73

Chapter 10 Status indicators for operation and communication

Manual output testThe manual output test sequentially turns off and on all binary outputs to verify their operation. The test overrides normal operation of the con-troller, which is suspended while the test is being performed.

Use the manual output test to:

• Verify output wiring and operation.• Force compressor operation so that a technician can use test equip-

ment to verify unit operation.• Clear diagnostics and restore normal operation (although not a pri-

mary function of the manual output test).

Perform the manual output test either by repeatedly pressing the Test button to proceed through the test sequence or by using the Rover service tool. Table 22 on page 75, Table 23 on page 75, and Table 24 on page 76 list the outputs in the sequence in which they are verified for the 2-heat/2-cool, 4-cool, and heat pump configurations, respectively.

To perform a manual output test:

1. Press and hold the Test button for 3 to 4 seconds, then release the button to start the test mode. The green LED light goes off when the Test button is pressed, and then it blinks (as described in Table 26 on page 77) when the button is released to indicate the controller is in manual test mode.

2. Press the Test button (no more than once per second) to advance through the test sequence. Table 22 shows the resulting activities of the binary outputs.

3. The controller exits the test mode after the final step or after 1 hour passes, whichever comes first.

Service Pin buttonUse the Service Pin button to verify that the controller is communicating on the network communications link, and to add devices and identify existing devices on the network communications link. See Figure 27 on page 73 for the location of the Service Pin button.

For more information about the function of the Service Pin button, see the Rover Operation and Programming guide (EMTX-SVX01B-EN) or the Tracker Building Automation System Hardware Installation guide (BMTK-SVN01A-EN).

Note:

The outputs are not subject to minimum on or off times during the test sequence. However, the test sequence permits only one step per second, which enforces a minimum output time.

74 CNT-SVX12C-EN

Service Pin button

Table 22. Manual output test sequence for 2-heat/2-cool configurations

Ste

p (

nu

mb

er

of

tim

es

Test

bu

tto

n is p

resse

d

in s

eq

uen

ce)

Re

su

lt

Fan

(G

)

Eco

no

miz

er

(OP

N)

Co

ol

sta

ge 1

(1

)

Co

ol

sta

ge 2

(2

)

Heat

sta

ge 1

(3)

Heat

sta

ge 2

(4)

Ex

ha

ust

fan

/gen

eri

c/

occu

pa

ncy

(5N

O/5

CO

M/5

NC

)

1 Begins test mode Off Off Off Off Off Off Off

2 Fan on1 On Off Off Off Off Off Off

3 Compressor 1 On Off On Off Off Off Off

4 Compressor 2 On Off On On Off Off Off

5 Heat 1 On Off Off Off On Off Off

6 Heat 2 On Off Off Off On On Off

7 Outdoor air damper On On Off Off Off Off Off

8 Generic/exhaust fan/occupancy On Off Off Off Off Off On

9 Exit2 Off Off Off Off Off Off Off1 At the beginning of Step 2, the controller attempts to clear all diagnostics.2 This step exits the manual output test and initiate a reset to restore the controller to normal operation.

Table 23. Manual output test sequence for 4-cool configurations

Ste

p (

nu

mb

er

of

tim

es

Test

bu

tto

n is p

ressed

in

seq

uen

ce)

Re

su

lt

Fan

(G

)

Eco

no

miz

er

(OP

N)

Co

ol

sta

ge 1

(1)

Co

ol

sta

ge 2

(2)

Heat

sta

ge 1

(3)

Heat

sta

ge 2

(4)

Exh

au

st

fan

/ge

neri

c/

occu

pa

ncy

(5N

O/5

CO

M/5

NC

)1 Begins test mode Off Off Off Off Off Off Off


3 Compressor 1 On Off On Off Off Off Off

4 Compressor 2 On Off On On Off Off Off

5 Compressor 3 On Off On On On Off Off

6 Compressor 4 On Off On On On On Off




CNT-SVX12C-EN 75


Interpreting LEDsThe red LED on the Tracer ZN517 unitary controller (see Figure 27 on page 73) indicates whether the controller is not working properly (see Table 25).

Table 24. Manual output test sequence for heat pump configurations

Ste

p (

nu

mb

er

of

tim

es

Test

bu

tto

n is p

resse

d

in s

eq

uen

ce)

Re

su

lt

Fan

(G

)

Eco

no

miz

er

(OP

N)

Co

ol

sta

ge 1

(1

)

Co

ol

sta

ge 2

(2

)

Heat

sta

ge 1

(3)

Heat

sta

ge 2

(4)

Ex

ha

ust

fan

/gen

eri

c/

occu

pa

ncy

(5N

O/5

CO

M/5

NC

)

1 Begins test mode Off Off Off Off Off Off Off


3 Reversing valve on On Off Off Off On Off Off

4 Compressor 1 On Off On Off On Off Off

5 Compressor 2 On Off On On On Off Off

6 Compressors off On Off Off Off Off Off Off

7 Auxiliary heat On Off Off Off Off On Off




Table 25. Red LED: Service indicator

LED activity Explanation

LED is off continuously when power is applied to the controller.

The controller is operating normally.

LED is on continuously when power is applied to the controller.

The controller is not working prop-erly, or someone is pressing the Ser-vice button.

LED flashes once every second. The controller is not executing the application software because the net-work connections and addressing have been removed.1

1 Restore the controller to normal operation using the Rover service tool. Refer to EMTX-SVX01B-EN for more information.

76 CNT-SVX12C-EN

Interpreting LEDs

The green LED on the Tracer ZN517 unitary controller (see Figure 27 on page 73) indicates whether the controller has power applied to it and if the controller is in manual test mode (see Table 26).

The yellow LEDs on the Tracer ZN517 unitary controller (see Figure 27 on page 73) indicate the controller’s communications status (see Table 27).

Table 26. Green LED: Status indicator


LED is on continuously. Power is on (normal operation).

LED blinks (one recurring blink). Manual output test mode is being performed and no diagnostics are present.

LED blinks (blinks twice as a recur-ring sequence).

Manual output test mode is being performed and one or more diag-nostics are present.

LED blinks (1/4 second on, 1/4 second off for 10 seconds).

The Auto-wink option is activated, and the controller is communicat-ing.1

LED is off continuously. Either the power is off, the controller has malfunctioned, or the Test button is being pressed.

1 By sending a request from the Rover service tool, you can request the controller’s green LED to blink (“wink”), a notification that the controller received the signal and is communicating.

Table 27. Yellow LED: Communications indicator


LED is off continuously The controller is not detecting any communication (normal for stand-alone applications).

LED blinks. The controller detects communica-tion (normal for communicating applications, including data sharing).

LED is on continuously. Abnormal condition.

CNT-SVX12C-EN 77


DiagnosticsIn response to a diagnostic, the controller attempts to protect the equip-ment it is controlling by disabling all the outputs. When the diagnostic clears, the controller resumes normal operation.

Diagnostic types

The Tracer ZN517 has two types of diagnostics: informational and auto-matic (also referred to as nonlatching). Informational diagnostics provide information about the status of the controller. They do not affect machine operation. They can be cleared from the controller in one of the following ways:

• By using the Rover service tool (see “Resetting a diagnostic” in EMTX-SVX01B-EN, Rover Operation and Programming guide.)

• Through a building automation system (see product literature)• By initiating a manual output test at the controller (see “Manual out-

put test” on page 74)• By cycling power to the controller. When the 24 Vac power to the con-

troller is cycled off and then on again, a power-up sequence occurs.

Automatic (nonlatching) diagnostics clear automatically when the prob-lem that generated the diagnostics is solved.

78 CNT-SVX12C-EN

Diagnostics

Table of diagnostics

Table 28 describes each diagnostic that can be generated by the Tracer ZN517.

Table 28. Diagnostics for the ZN517 unitary controller

Diagnostic Probable cause ConsequencesDiagnostic

type

P Normal Default value until power-up control wait expires

None N/A

Normal Default value after power-up control wait expires

None N/A

Local Space Setpoint Failure Invalid or missing value for space setpoint

The controller uses default values. Informational

Maintenance Required The maintenance required timer has expired

Informational warning only. Informational

Local Fan Switch Failure BI2 has not seen a contact closure for 60 seconds, indi-cating fan proving

All binary outputs are disabled. Automatic

CO2 Sensor Failure CO2 input is invalid or missing

Demand control ventilation is disabled.

Automatic

Discharge Air Temp Failure Discharge air temperature input is invalid or missing


Invalid Unit Configuration Invalid DIP switch setting Controller will not operate. Automatic

RH Sensor Failure Relative humidity input is invalid or missing

Dehumidification is disabled. Automatic

Space Temperature Failure Space temperature sensor is invalid or missing


CNT-SVX12C-EN 79


80 CNT-SVX12C-EN

Chapter 11

General wiring information

This chapter provides specifications and general information about wir-ing the Tracer ZN517 unitary controller. The controller requires wiring for:

• Input/output terminals• AC power to the controller• Communication-link wiring, if the controller is to communicate with a

building automation system (BAS)

Input/output terminal wiringAll input/output terminal wiring for the Tracer ZN517 unitary controller is application specific and dependant on the configuration of the control-ler. For application-specific wiring information and diagrams, see Chapter 3, “Applications for the 2-heat/2-cool configuration”,” Chapter 5, “Applica-tions for the 4-cool configuration”,” and Chapter 7, “Applications for the heat pump configuration”.”

Wiring specifications

Input/output terminal wiring must meet the following requirements:

• All wiring must comply with the National Electrical Code and local codes.

• Use only 18 AWG twisted-pair wire with stranded, tinned-copper con-ductors. (Shielded wire is recommended.)

• Binary input and output wiring must not exceed 1000 ft (300 m).• Analog input wiring must not exceed 300 ft (100 m).• Do not run input/output wires in the same wire bundle with any ac

power wires.

CNT-SVX12C-EN 81

Chapter 11 General wiring information

HVAC unit electrical circuit wiring

The terminals labeled Rc and Rh are provided as inputs for 24 Vac power from the transformer(s) of the HVAC system.

Packaged units

If the HVAC unit combines heating and cooling (referred to as a “pack-aged” unit), it will typically have one “R” transformer. For 24 Vac wiring of packaged units, the Rc terminal must be wired as shown in this procedure:

1. Locate the jumper at J1 on the controller circuit board (Figure 28 on page 83). Place the jumper on both pins at J1 on the circuit board (Figure 29 on page 83).

2. Wire the Rc terminal to the transformer on the unit (Figure 30 on page 84).

Split systems

If the unit is a split system (a unit with physically separate heating and cooling sections), there is typically a separate transformer for each func-tion. For 24 Vac wiring of split systems, the Rc and Rh terminals must be wired as show in this procedure:

1. Locate the jumper at J1 on the controller circuit board (Figure 28 on page 83). Remove the jumper from the pins at J1 on the circuit board (Figure 29 on page 83).

2. Replace the jumper on one of the pins at J1 for possible future use.

3. Wire Rc to the transformer for the cooling section of the unit(Figure 31 on page 84).

4. Wire Rh to the transformer for the heating section of the unit (Figure 31 on page 84).

Note:

The Tracer ZN517 is shipped from the factory with terminals Rc and Rh coupled with the jumper at J1 on the controller cir-cuit board.

82 CNT-SVX12C-EN

Input/output terminal wiring

Figure 28. Location of J1 on Tracer ZN517 circuit board

Figure 29. Coupling and uncoupling terminals Rc and Rh for 24 Vac

wiring of the HVAC unit

J1 (location of jumper for Rc, Rh terminals)

J1 J1Place the jumper on both pins at J1.

For packaged units

Remove the jumper from one of the pins at J1. (Leave it on one of the pins for possible future use.)

For split systems

CNT-SVX12C-EN 83


Figure 30. Wiring for packaged heating and cooling units

Figure 31. Wiring for split system applications


Heat stage 1


Fan

HN

24 VacGeneric binary output (dry contact)


Heat stage 2

Primary

Secondary, 24 Vac

G Y1 Y2R W1 W2


Heat stage 1


Fan*

HN

24 Vac

Generic binary output (dry contact)


Heat stage 2

Primary

Secondary, 24 Vac

G Y1 Y2Rc W1 W2

Primary

Secondary, 24 Vac

Rh

*Wire the fan (G) to the appropriate section of the split system.

84 CNT-SVX12C-EN

AC power wiring

AC power wiring

CAUTION

Equipment damage!

Complete input/output wiring before applying power to the Tracer

ZN517 unitary controller. Failure to do so may cause damage to the con-

troller or power transformer due to inadvertent connections to power

circuits.

CAUTION

Hazardous voltage!

Make sure that the 24 Vac transformer is properly grounded. Failure to

do so may result in damage to equipment and/or minor or moderate

injury.

IMPORTANTDo not share 24 Vac between controllers.

All wiring must comply with National Electrical Code and local codes.

The ac power connections are in the top left corner of the Tracer ZN517 unitary controller (see Figure 32).

Figure 32. Connecting ac power wires to the controller

If you are providing a new transformer for power, use a UL-listed Class 2 power transformer supplying a nominal 24 Vac (19–30 Vac). The trans-former must be sized to provide adequate power to the Tracer ZN517 uni-tary controller (9 VA) and output devices, including relays and valve actuators, to a maximum of 12 VA per output utilized. The Tracer ZN517 may be powered by an existing transformer integral to the controlled heat pump, provided the transformer has adequate power available and ade-quate grounding is observed.

24 Vac unit transformer

H

N

CNT-SVX12C-EN 85


Communication-link wiring and

addressingThe Tracer ZN517 unitary controller communicates with a BAS and with other LonTalk controllers via a LonTalk communication link. For instruc-tions on LonTalk communication wiring and addressing, follow the requirements given in the Tracer Summit Hardware and Software Instal-lation guide (BMTX-SVN01A-EN) or the Tracker Building Automation System Hardware Installation guide (BMTK-SVN01D-EN) or another BAS installation manual.

86 CNT-SVX12C-EN

Chapter 12

Troubleshooting

This chapter outlines some general troubleshooting steps that should be performed if there is a problem with the operation of the equipment con-trolled by the Tracer ZN517 unitary controller. This chapter describes some common problems; however, it cannot describe every possible problem.

If you encounter operational problems with the Tracer ZN517, you must first perform initial troubleshooting steps; see “Initial troubleshooting” on page 88. After this procedure, consult the tables in “Diagnosing opera-tional problems” on page 88 for further troubleshooting assistance.

CNT-SVX12C-EN 87

Chapter 12 Troubleshooting

Initial troubleshootingAlways perform the initial troubleshooting steps listed in Table 29 before moving on to the specific area of trouble. Perform the steps in the order they are listed.

Diagnosing operational problemsAfter you have performed the initial troubleshooting steps, refer to the succeeding tables in this chapter to further diagnose the following opera-tional problems:

• Fan does not energize (Table 30 on page 89)• Heat does not energize (Table 31 on page 90)• An outdoor air damper stays closed (Table 32 on page 90)• An outdoor air damper stays open (Table 33 on page 91)

Table 29. Initial troubleshooting steps

Step number Action Probable cause

Step 1 Look at the red Service LED. If it is flashing once per second, the controller is not executing the application software because the network connections and addressing have been removed. For a complete explanation of this LED’s behavior, see Table 25 on page 76.Use the Rover service tool or a BAS to restore normal operation. See EMTX-SVX01B-EN for more information.

Tracer ZN517 is not configured

Step 2 Look at the green Status LED. It should be on continuously during normal operation. A blinking Status LED indicates the Tracer ZN517 is performing a manual output test. For a complete explanation of this LED’s behavior, see Table 26 on page 77.

Tracer ZN517 is in manual output test mode

Step 3 Take your meter (set to measure ac voltage) and measure the voltage across the ac-power terminals on the Tracer ZN517 (with ac wires connected). See Figure 32 on page 85. If you see approximately 24 V (21–27 V) on those terminals, the board is receiving adequate input power and you likely have a Tracer ZN517 circuit board problem.

Tracer ZN517 cir-cuit board prob-lem

Step 4 Disconnect the ac wires from the input power terminals. Take your meter (set to measure ac voltage) and measure the voltage across the ac wires. If you see approximately 0 V, the board is not receiving the power it needs to run.

Input power prob-lem

Step 5 Reconnect the ac wires to the input power terminals. Perform the manual output test, which is described in “Manual output test” on page 74.If the outputs on the controller do not behave as described in the manual output test (page 74), then you are likely to have a Tracer ZN517 circuit board problem.

Tracer ZN517 cir-cuit board prob-lem

88 CNT-SVX12C-EN

Diagnosing operational problems

Table 30. Fan does not energize

Probable cause Explanation

Unit wiring The wiring between the controller outputs and the fan relays and contacts must be present and correct for normal fan operation. Refer to applicable wiring diagram.

Failed end device The fan motor and relay must be checked to ensure proper operation

Random start observed

After power-up, the controller always observes a random start from 0 to 25 seconds. The controller remains off until the random start time expires.

Power-up control-wait If power-up control-wait is enabled (non-zero time), the controller remains off until one of two conditions occurs:1) The controller exits power-up control-wait once it receives communicated information.2) The controller exits power-up control-wait once the power-up control-wait time expires.

Cycling fan operation If configured to cycle with capacity, normally the fan cycles off with heating or cooling. The heating/cooling sources cycle on or off periodically with the fan to provide varying amounts of capacity to the zone.

Unoccupied operation Even if the controller is configured for continuous fan operation, the fan normally cycles with capacity during unoccupied mode. While unoccupied, the fan cycles on or off with heating/cooling to provide varying amounts of heating or cooling to the space.

Fan mode off If a local fan mode switch determines the fan operation, the off position controls the fan off.

Requested mode off You can communicate a desired operating mode (such as off, heat, and cool) to the con-troller. If off is communicated to the controller, the unit controls the fan off. There is no heating or cooling.

Diagnostic present For information about diagnostics, see Table 28 on page 79.

No power to the con-troller

If the controller does not have power, the unit fan does not operate. For the Tracer ZN517 controller to operate normally, it must have an input voltage of 24 Vac. If the green LED is off continuously, the controller does not have sufficient power or has failed.

Unit configuration The controller must be properly configured based on the actual installed end devices and application. If the unit configuration does not match the actual end device, the valves may not work correctly.

Manual output test The controller includes a manual output test sequence you can use to verify output oper-ation and associated output wiring. However, based on the current step in the test sequence, the unit fan may not be on. Refer to the “Manual output test” on page 74.

CNT-SVX12C-EN 89


Table 31. Heat does not energize


Unit wiring The wiring between the controller outputs and the electric heat contacts must be present and correct for normal electric heat operation. Refer to applicable wiring diagram.

Failed end device Check electric heat element, including any auxiliary safety interlocks, to ensure proper operation.

Normal operation The controller controls electric heat on and off to meet the unit capacity requirements.

Requested mode off You can communicate a desired operating mode (such as off, heat, and cool) to the con-troller. If off is communicated to the controller, the unit shuts off all electric heat.

Unit configuration Check to make sure unit is not in the 4-cool configuration.

Communicated dis-able

Numerous communicated requests may disable electric heat, including an auxiliary heat enable input and the heat/cool mode input. Depending on the state of the communicated request, the unit may disable electric heat.

Manual output test The controller includes a manual output test sequence you can use to verify output oper-ation and associated output wiring. However, based on the current step in the test sequence, the electric heat may not be on. Refer to the “Manual output test” on page 74.


No power to the con-troller

If the controller does not have power, electric heat does not operate. For the ZN517 con-troller to operate normally, you must apply an input voltage of 24 Vac. If the green LED is off continuously, the controller does not have sufficient power or has failed.

Table 32. Outdoor air damper remains closed


Unit wiring The wiring between the controller outputs and the outdoor air damper must be present and correct for normal outdoor air damper operation. Refer to applicable wiring diagram.

Failed end device Check damper actuator to ensure proper operation.

Normal operation

The controller opens and closes the outdoor air damper based on the controller’s occu-pancy mode and fan status. Normally, the outdoor air damper is open during occupied mode when the fan is running and closed during unoccupied mode.

Warm up and cool down

The controller includes both a morning warm up and cool down sequence to keep the outdoor air damper closed during the transition from unoccupied to occupied. This is an attempt to bring the space under control as quickly as possible.

Requested mode off You can communicate a desired operating mode (such as off, heat, or cool) to the control-ler. If off is communicated to the controller, the unit closes the outdoor air damper.

Manual output test The controller includes a manual output test sequence you can use to verify output oper-ation and associated output wiring. However, based on the current step in the test sequence, the outdoor air damper may not be open. Refer to the “Manual output test” on page 74.


90 CNT-SVX12C-EN

Diagnosing operational problems

Unit configuration The controller must be properly configured based on the actual installed end devices and application. If the unit configuration does not match the actual end device, the outdoor air damper may not work correctly.

No power to the controller

If the controller does not have power, the outdoor air damper does not operate. For the ZN517 controller to operate normally, you must apply an input voltage of 24 Vac. If the green LED is off continuously, the controller does not have sufficient power or has failed.

Table 33. Outdoor air damper remains open


Unit wiring The wiring between the controller outputs and the outdoor air damper must be present and correct for normal outdoor air damper operation. Refer to applicable wiring diagram.

Failed end device Check damper actuator to ensure proper operation.

Normal operation

The controller opens and closes the outdoor air damper based on the controller’s occu-pancy mode and fan status. Normally, the outdoor air damper is open during occupied mode when the fan is running and closed during unoccupied mode.

Manual output test The controller includes a manual output test sequence you can use to verify output oper-ation and associated output wiring. However, based on the current step in the test sequence, the outdoor air damper may be open. Refer to the “Manual output test” on page 74.

Unit configuration

The controller must be properly configured based on the actual installed end devices and application. If the unit configuration does not match the actual end device, the outdoor air damper may not work correctly.

Table 32. Outdoor air damper remains closed (Continued)


CNT-SVX12C-EN 91


92 CNT-SVX12C-EN

CNT-SVX12C-EN

Index

Numerics

24 Vac wiring, 85

2-heat/2-cool configurationAnalog inputs, 15–18Binary inputs, 14Binary output 5 (5NO/5COM/5NC),

13Binary outputs, 13–14Demand control ventilation, 24DIP switch settings, 12Discharge air temperature input, 17Discharge air tempering, 24Economizing, 17, 23Exhaust fan output, 13Fan off delay, 25Fan operation, 23Fan status, 25Fan status input, 14Filter-maintenance timer, 25Generic binary input, 14Generic binary output, 13Manual output test sequence, 75Occupancy modes, 20Occupancy or generic input, 14Occupancy output, 13Outdoor air damper operation, 22Peer-to-peer data sharing, 23Required and optional components,

10Required and optional inputs and

outputs, 10Sequence of operations, 19–25Temperature setpoint input, 18Timed override control, 22Unit protection strategies, 24Wiring diagram, 11Zone temperature input, 18

4-cool configurationAnalog inputs, 33–36Binary inputs, 32Binary output 5 (5NO/5COM/5NC),

31Binary outputs, 31Demand control ventilation, 42DIP switch settings, 30Discharge air temperature input, 35Discharge air tempering, 42Economizing, 35, 41

Exhaust fan output, 31Fan off delay, 43Fan operation, 41Fan status, 43Fan status input, 32Filter-maintenance timer, 43Generic binary input, 32Generic binary output, 31Manual output test sequence, 75Occupancy modes, 38Occupancy or generic input, 32Occupancy output, 31Outdoor air damper operation, 40Peer-to-peer data sharing, 41Required and optional components,

28Required and optional inputs and

outputs, 28Sequence of operations, 37–43Temperature setpoint input, 36Timed override control, 40Unit protection strategies, 42Wiring diagram, 29Zone temperature input, 36

A

AC power wiring, 85

ActuatorMinimizing activity with error

deadband, 69

Actuators, damper, 6

Additional application-dependent components, 6

Agency listing/compliance, 4

Analog inputsAI1 (Universal 4–20 mA), 15, 33, 51AI1 configuration options, 15, 33,

51AI1 configured for CO2

measurement, 16, 34, 52AI1 configured for RH

measurement, 16, 34, 52AI1 generic configuration, 15, 33, 51AI2 (Outdoor air or generic

temperature), 17, 35, 53AI2 configuration options, 17, 35, 53

93

Index

AI2 generic temperature configuration, 17, 35, 53

Generic temperature, 17, 35, 53

Analog inputs, 2-heat/2-coolDAT (Discharge air

temperature), 17SET (Temperature setpoint), 18Table, 15ZN (Zone temperature), 18

Analog inputs, 4-coolDAT (Discharge air


Analog inputs, heat pumpDAT (Discharge air


ApplicationsHeat pump, 45Rooftop units, 9, 27, 31Split systems, 9

Applications, 2-heat/2-cool, see 2-heat/2-cool configuration

Applications, 4-cool, see 4-cool configuration

Applications, heat pump, see Heat pump configuration

B

BAS communication, 1, 86

Binary inputs, 2-heat/2-coolBI1 (Occupancy or generic), 14BI2 (Fan status), 14Table, 14

Binary inputs, 4-coolBI1 (Occupancy or generic), 32BI2 (Fan status), 32Table, 32

Binary inputs, heat pumpBI1 (Occupancy or generic), 50BI2 (Fan status), 50Table, 50

Binary output 5 (5NO/5COM/5NC)2-heat/2-cool, 134-cool, 31Heat pump, 49

Binary outputs2-heat/2-cool, 13–144-cool, 31Configuration options for binary

output 5 (5NO/5COM/5NC), 13, 31, 49

Heat pump, 49

Binary outputs, 2-heat/2-coolExhaust fan, 13Generic, 13Occupancy, 13Overriding, 14Table, 13

Binary outputs, 4-coolExhaust fan, 31Generic, 31Occupancy, 31Overriding, 31Table, 31

Binary outputs, heat pumpExhaust fan, 49Generic, 49Occupancy, 49Overriding, 49Table, 46, 49

Building automation system communication, 1, 86

C

CalculationsIn PID loops, 64–65

Cascade zone control2-heat/2-cool, 204-cool, 38Heat pump, 56

CE, see Agency listing/compliance

Circuit boardDiagram, 73jumper (J1) location, 83

CO2 measurement input, 16, 34, 52

Compliance

Compressor operation, 59

Configuration optionsAI1 (Generic, CO2, or RH), 15,

33, 51AI2 (Outdoor air or generic

temperature), 17, 35, 53BI1 (Occupancy or generic), 14,

32, 50

Binary output 5 (exhaust fan, occupancy, or generic), 13, 31, 49

Configurations2-heat/2-cool, 9–254-cool, 27–43Heat pump, 45–62

D

Damper actuators, 6

Demand control ventilation, 24, 42, 60

Derivative calculation, PID loops, 65

Derivative control, 65

Diagnosing operational problems, 87–91

DiagnosticsAutomatic, 78CO2 Sensor Failure, 16, 34, 52,

79Disable generation of, 15, 33, 51Discharge Air Temp Failure, 79General, 78Informational, 78Invalid Unit Configuration, 79Local Fan Switch Failure, 14, 32,

50, 79Local Space Setpoint Failure, 18,

36, 54, 79Maintenance Required, 25, 43,

62, 79Nonlatching, 78Normal, 79P Normal, 79RH Sensor Failure, 16, 34, 52, 79Space Temperature Failure, 18,

19, 36, 37, 54, 55, 79Table, 79Types, 78

Dimensional diagram, 3

Dimensions, 1

DIP switch settings2-heat/2-cool configuration, 124-cool configuration, 30Economizing, 17, 35, 53Heat pump configuration, 48

Direct action of PID loops, 68

Discharge air temperature input2-heat/2-cool configuration, 174-cool configuration, 35Heat pump configuration, 53

94 CNT-SVX12C-EN

Index

Discharge air temperaturesensors, 6

Discharge air tempering, 24, 42, 60

E

Economizing, 17, 23, 35, 41, 53, 60

EquipmentRooftop units, 13Split systems, 13

Error deadband, 69–70Adjusting for modulating

outputs, 69Adjusting for staged outputs,

69–70

F

Fan off delay, 25, 43, 62

Fan status, 25, 43, 62

Fan status input2-heat/2-cool configuration, 144-cool configuration, 32Heat pump configuration, 50

FansOperation, 23, 41, 59Troubleshooting, 89

Filter-maintenance timer, 25, 43, 61

Free cooling, see Economizing

G

GainsChanging, to troubleshoot

specific problems, 72

GenericTemperature input, 17, 35, 53

Generic binary input2-heat/2-cool, 144-cool, 32Heat pump, 50

Generic binary output2-heat/2-cool, 134-cool, 31Heat pump, 49

GND terminal, analog inputs, 15, 33, 51

Grounding power transformers, 85

H

Heat failure, troubleshooting, 90

Heat pump applications, 45Components, 49

Heat pump configurationAnalog inputs, 51–54Binary inputs, 50Binary output 5 (5NO/5COM/

5NC), 49Binary outputs, 49Compressor operation, 59Demand control ventilation, 60DIP switch settings, 48Discharge air temperature input,

53Discharge air tempering, 60Economizing, 53, 60Exhaust fan output, 49Fan off delay, 62Fan operation, 59Fan status, 62Fan status input, 50Filter-maintenance timer, 61Generic binary input, 50Generic binary output, 49Heating or cooling mode, 59Manual output test sequence,

76Occupancy modes, 56Occupancy or generic input, 50Occupancy output, 49Outdoor air damper operation,

58Peer-to-peer data sharing, 61Required and optional

components, 46Required and optional inputs

and outputs, 46Reversing valve operation, 59Sequence of operations, 55–62Temperature setpoint input, 54Timed override control, 58Unit protection strategies, 61Wiring diagram, 47Zone temperature input, 54

Heating or cooling modeHeat pump configuration, 59

HumidityMeasurement input, 16, 34, 52

HVAC packaged unitsWiring, 82Wiring diagram, 84

HVAC split systemsWiring, 82Wiring diagram, 84

HVAC unit electrical circuit wiring, 82–84

I

Input/output terminal wiring, 81

Integral calculation, PID loops, 64

Integral control, 64

J

Jumper (J1) location, 83

L

LEDsGeneral, 73Interpreting green (status), 77Interpreting red (service), 76Interpreting yellow

(communications), 77Location, 73

LonTalk communication, 86Description, 1

LonTalk protocol, see LonTalk communication

M

Manual output test, 74–76

Manual output test sequence2-heat/2-cool, 754-cool, 75Heat pump, 76

MountingCover, 8Diagram, 8Location, 7Operating environment, 2Procedures, 8

N

National Electrical Code, 81, 85

CNT-SVX12C-EN 95

Index

O

Occupancy modes, 2-heat/2-coolGeneral, 20Occupied, 21Occupied bypass, 22Occupied standby, 21Unoccupied, 21

Occupancy modes, 4-coolGeneral, 38Occupied, 39Occupied bypass, 40Occupied standby, 39Unoccupied, 39

Occupancy modes, heat pumpGeneral, 56Occupied, 57Occupied bypass, 58Occupied standby, 57Unoccupied mode, 57

Occupancy or generic input2-heat/2-cool configuration, 144-cool configuration, 32Heat pump configuration, 50

Operating environment, 2

Outdoor air damperOperation, 22, 40, 58

Outdoor air damper remains closedTroubleshooting, 90

Outdoor air damper remains openTroubleshooting, 91

Outdoor air or generic temperatureInput, 17, 35, 53

Outdoor air temperature input, 17, 35, 53

Overriding binary outputs2-heat/2-cool, 144-cool, 31General, 74Heat pump, 49

Overshooting the setpoint, 63

P

Peer-to-peer data sharing, 23, 41, 61

PID loops, 63–72Action, 68Calculations, 64–65Definition, 63Derivative calculation, 65Direct action, 68Effects of aggressiveness, 63

Error deadband, 69–70Integral calculation, 64Managing with additional

settings, 71Overview, 63Proportional calculation, 64Reverse action, 68Sampling frequency for

calculations, 65–67Tips for specific problems, 72Troubleshooting, 71–72

Power requirements, 2, 4

Power transformers, 6

Power wiring, 85

Power-up sequence, 19, 37, 55

Product description, 1

Proportional calculation, PID loops, 64

Proportional, integral, derivative (PID) loops, see PID loops

Protection strategies2-heat/2-cool, 244-cool, 42Heat pump, 61

R

Rc, Rh terminal wiring, 82–84Coupling and uncoupling with

jumper, 83

Reverse action of PID loops, 68

Reversing valve operation, 59

Rooftop units, 9, 13, 27, 31

Rover, 1

Rover service tool, 1, 4, 13, 18, 20, 21, 22, 23, 24, 25, 31, 36, 38, 39, 40, 41, 42, 43, 49, 54, 56, 57, 58, 60, 61, 62, 63, 74, 76, 77, 78, 88

S

Sampling frequency, 65–67Changing, to troubleshoot

specific problems, 72

see LonTalk communication, 86

SensorsApplication-specific, 15, 33, 51CO2, 16, 34, 52Discharge air temperature, 6, 20,

38, 56

Occupancy, 14, 32, 50Table of options, 6Zone humidity, 16, 34, 52Zone temperature, 6

Sequence of operations, 2-heat/2-cool

Demand control ventilation, 24Discharge air tempering, 24Economizing, 23Fan off delay, 25Fan operation, 23Fan status, 25Filter-maintenance timer, 25Occupancy modes, 20Outdoor air damper operation,

22Peer-to-peer data sharing, 23Power-up sequence, 19Timed override control, 22Unit protection strategies, 24

Sequence of operations, 4-coolDemand control ventilation, 42Discharge air tempering, 42Economizing, 41Fan off delay, 43Fan operation, 41Fan status, 43Filter-maintenance timer, 43Occupancy modes, 38Outdoor air damper operation,

40Peer-to-peer data sharing, 41Power-up sequence, 37Timed override control, 40Unit protection strategies, 42

Sequence of operations, heat pumpCompressor operation, 59Demand control ventilation, 60Discharge air tempering, 60Economizing, 60Fan off delay, 62Fan operation, 59Fan status, 62Filter-maintenance timer, 61Heating or cooling mode, 59Occupancy modes, 56Outdoor air damper operation,

58Peer-to-peer data sharing, 61Power-up sequence, 55Reversing valve operation, 59Timed override control, 58Unit protection strategies, 61

96 CNT-SVX12C-EN

Index

Service Pin buttonFunction, 74Location, 73

Setpoint, controlling with PID loop, 63

SettingsPID loops, 71

Simplified zone control2-heat/2-cool, 204-cool, 38Heat pump, 56

SpecificationsAgency listing/compliance, 4Dimensional diagram, 3Dimensions, 1Input/output terminal wiring, 81Power requirements, 2, 4Storage environment, 4Transformers, 85

Split systems, 9, 13

Status indicators for operation and communication

General, 73Green LEDs, 77Manual output test, 74Red LEDs, 76Service Pin button, 74Test button, 73, 74Yellow LEDs, 77

Storage environment, 4

T

Temperature sensorsDischarge air, 6Table of options, 6Zone, 6

Temperature setpoint input2- heat/2-cool configuration, 184-cool configuration, 36Heat pump configuration, 54

Test buttonFunction, 73Location, 73

Thermistor, 54

Timed override control2-heat/2-cool, 224-cool, 40Heat pump, 58

Transformers, 6, 85

Troubleshooting

Fans, 89Heat failure, 90Initial steps, 88Outdoor air damper remains

closed, 90Outdoor air damper remains

open, 91PID loops, general, 71–72PID loops, specific problems, 72

U

UL, see Agency listing/compliance

Unit protection strategies2-heat/2-cool configuration, 244-cool configuration, 42Heat pump configuration, 61

Universal 4–20 mA, 15, 33, 51

W

WiringAC power, 85Compliance with National

Electrical Code, 81, 85Connecting ac power, 85General, 81–86HVAC packaged units, 82HVAC packaged units, diagram,

84HVAC split systems, 82HVAC split systems, diagram, 84HVAC unit electrical circuit,

82–84Input/output terminals, 81LonTalk communication, 86Network communication, 86Requirements and options for 2-

heat/2-cool configuration, 10Requirements and options for 4-

cool configuration, 28Requirements and options for

heat pump configuration, 46

Wiring diagram2-heat/2-cool configuration, 114-cool configuration, 29Heat pump configuration, 47

Z

Zone temperature input2-heat/2-cool configuration, 184-cool configuration, 36Heat pump configuration, 54

Zone temperature sensors, 6

CNT-SVX12C-EN 97

Index

98 CNT-SVX12C-EN