Can Training Presentation

CAN: Controller Area Network

CANController Area Network

2 / Basica Liviu / 2009 © Continental AG For Internal Use Only

INTRO


What is CAN ?

Controller Area Network (CAN) is bus standard for automotive applications, originally developed in the 1980s by Robert Bosch GmbH, for connecting electronic control units (ECUs):

asynchronous;

bidirectional half duplex;

linear;

with protocol: address + data + data check + signal information;

multi-master: every node can start communication.

Requirements to Automation and Automotive Bus Systems:

The costs;

Transmission in a area with Radio Frequency noise;

Real-time behavior;

Easy handling;

Standardization.


How it began?

Engine control

Transmission control

Antilock Brakes

Active Suspension

Lighting

Power Seats

Air condition

Power windows

Instrument Cluster

(Dashboard)

High speed CAN Low speed CAN


CAN Advantages

Less wires;

Less connections;

Less weight;

Less EMI problems;

Less space required;

Easier addition of new nodes;

Lower assembly costs;

Increased transmission reliability;

Standardization: ISO 11898, 11519, 11992, SAE j1939...

ISO

DIN

SAE

CiA

“The great thing about standards is that there are so many to choose from.”


An ECU's CAN structure

Application LayerApplication Layer

Presentation LayerPresentation Layer

Session LayerSession Layer

Transport LayerTransport Layer

Network LayerNetwork Layer

Data Link LayerData Link Layer

Physical LayerPhysical Layer

ISO/OSI Model

CAN bus

CAN TransceiverCAN Transceiver

Application SoftwareApplication Software

CAN ControllerCAN Controller

CAN Subsystem on Host ControllerCAN Subsystem on Host Controller

HW

SW

ECU

All

People

Seem

To

Need

Data

Processing


HARDWARE


CAN Bus / Network

double wire linear bus – basic termination

~~~ ~

Network Node 1: e.g. Engine

Control

CAN-H

CAN-L

120 120

Network Node n: e.g. Airbag

double wire linear bus – split termination

RT /2 = 60

RT /2 = 60

RT /2 = 60

RT /2 = 60 Cg Cg = 10 .. 100nF

CAN_H

CAN_H


CAN Bus / Network

CAN star bus

RT = 180 RT = 180

RT = 180

The multiple termination concept is used when network architecture differs from linear structure e.g. the cable drop length of a few meters is needed. For such a topology a multiple termination concept with three branches needs about three times the total termination resistance: 180 .


CAN Bus / Network

Daimler-Chrysler Patented Star Topology

30

30 10 CAN

nodeCANnode

CAN_H

CAN_L

ferrite bead:

2 mH44 10 pF

Transceiver

Transceiver

Daimler-Chrysler have patented a star topology with a common termination. This topology avoids resonance problems, undesired harmonics and it's insensitive to incoming noise. All noise traveling towards the termination point will be absorbed there and never reflected.


CAN Bus / Network

The communication in a car may be classified into three classes.

Related to the performance of different systems there are:

Class A - used for low-speed data communication: up to 10 kbit/s;

Class B - used for status and diagnostic data sharing: 10 to 125 kbit/s;

Class C - is used for real-time application communication at high speeds of 125 kbit/s to 1 Mbit/s.

CAN Transmission via Fiber Optic Cable

Very high transmission rates are possible;

Access to data in systems with very high electromagnetic noise;

Data transmission of sensitive data in systems with very high security requirements is possible.


CAN Bus / Network

Recessive RecessiveDominant

CAN-L

CAN-H3.5

2.5

1.5

Volts

Time

High-Speed definitions according to ISO 11898


CAN Bus / Network

Recessive RecessiveDominant

CAN-L

CAN-H

3.25

1.75

1.0

Volts

Time

4.0

Low-Speed definitions according to ISO 11519


Physical Layer: CAN Transceiver

The transceiver is able to convert a digital CAN controller signal in a symmetrical differential one and vice versa.

Some of these transceiver offer special features like:

slope control;

bus short circuit protection to battery voltage and ground;

single wire transmission in case of short circuit of bus lines;

receive filter (low pass filter) against glitches (e.g. less 30 ns).

ISO 11898, ISO 11992, ISO 11519.


Physical Layer: CAN Transceiver

GND

TxD CAN_H

CAN_L

Rs

C CAN_H

CAN_L

PCA82C250

RxD

Vref

VCC

Vref reference voltage outputTxD transmit data inputRxD receive data outputGND ground

Rs slope resistor inputCAN_H HIGH level CAN voltage input / outputCAN_L LOW level CAN voltage input / outputVcc supply voltage

e.g. High Speed Double-Wire Transceiver PCA 82C250

- ISO/DIS 11898 compatible- High Speed (up to 1 Mbit/s)- Standby Mode- Slope Control / Standby- Short circuit protection for - CAN_L and CAN_H


Physical Layer: CAN Controller

To be able to participate in the CAN communication, the micro-controller has to be connected to a CAN protocol controller.

The CAN controller may be a different chip or be integrated into the microcontroller:

Microcontroller

CAN controller

Transceiver

Microcontroller

Transceiver

CAN controller

CAN Bus


Physical Layer: On-chip CAN Controller


Physical Layer: Basic CAN

There are two types of microcontroller with on-chip CAN module:

Basic CAN Controller:

Limited number of Rx and Tx Buffers;

Reception of all CAN identifiers, all the time;

High CPU load;

Cheap implementation;

CAN

Controller

memory

area

Tx MessageObject 1

General Register Set

Rx MessageObject 1

Rx MessageObject 2

Tx MessageObject 2 opt.

Message Object Register:

- Data 0 .. Data 7

- Message Configuration

- Arbitration Mask

- Message Control

General Registers for:

- CAN Controller Init

- Handling of Status Information


Physical Layer: Full CAN

Full CAN Controller:

Many Full-CAN controller provide a "Basic-CAN-Feature";

Large number of buffers for Rx and Tx;

Buffers can be pre-defined for specific identifiers;

All transmit frames in these buffers participate in arbitration;

Less CPU load;

More expensive;

CAN

Controller

memory

area

Message Object Register:

- Data 0 .. Data 7

- Message Configuration

- Arbitration Mask

- Message Control

General Registers for:

- CAN Controller Init

- Handling of Status Information

Message Object 1

General Register Set

Message Object n...


Physical Layer: Bit timing

Problem:

Frequencies of the quartz oscillators of the CAN nodes usually differ;

Re-synchronization of nodes during transmission is necessary;

Solution: CAN Bit Timing

CAN Bit Timing divides the bit time into several segments;

Segments 1 and 2 can be lengthened or shortened during transmission;

Re-synchronization of nodes during transmission is possible.

Bit time

tq

SynchSegm

Propagation Time Segment

Phase Buffer Segment 2Phase Buffer Segment 1

sample point


Physical Layer: The communication

Transmission with Carrier Sense Multiple Access with Collision Avoidance CSMA/CA;

each node monitors the bus;

each node can start transmission;

arbitration: dominant bits (low) win against recessive bits (high) on bus;

the arbitration winner continues transmission;

Node A Node B

V+

Receive

Node N

V+

Receive Receive

dominantrecessive recessive1 (high)

0 (low)

Bus Line

Transmit TransmitTransmit


Physical Layer: Arbitration

The arbitration of messages on the CAN bus is a hardware implemented bit-wise process.

If one node switches a “HIGH” and reads a “LOW” he loses the arbitration and stops his transmission immediately.

The lowest address number (ID) will always win this arbitration without any information loss of his message

Bus Level

Node A

Node B

Idle

Idle

Idle

Start Bit

Start Bit listening only

dominant

dominant

recessive


Physical Layer: Bit Coding - Bit Stuffing

CAN data is transmitted with NRZ (No-Return to Zero) bit coding;

Problems when using NRZ coding:

long sequences of bits of the same polarity;

no changes in voltage level for a longer time;

no falling edges for synchronization;

synchronization between sender and receiver may be lost;

Solution: Bit stuffing

after five consecutive bits of same polarity, insert one bit of reverse polarity;

CRC code is calculated before bit stuffing is done;

bit stuffing is done by the sender directly before transmission;

de-stuffing is done by the receiver directly after reception;

CRC code check is done after de-stuffing the frame;

bit stuffing is applied to part of the frame from SOF to CRC field


Data Link Layer: The message – Data Frame

Data frames: generated by a CAN node when a node wishes to transmit data;

standard frame – 11bit identifier (also called CAN 2.0A);

extended frame – 29bit identifier (also called CAN 2.0B);



SOF: Start of Frame. SOF = 0;

marks the start of any CAN frame;

provides a falling edge for hard synchronization of transmitter and receivers

IDE: Identifier Extension

IDE = 0 – Standard Frame;

IDE = 1 – Extended Frame;

DLC: Data Length Code

the bytes number of the data field

Data Field: contains the actual information to be transmitted;

number of data bytes may range from 0 to 8 in units of bytes;

transmission starts with the first data byte (byte 0), MSB first



CRC: Cyclic Redundancy Check

15 bit check sum generated by transmitter and controlled by receiver

the CRC Field Delimiter (DEL) marks the end of the CRC field

ACK: Acknowledge – on Tx is recessive and on Rx is dominant;

the ACK Field Delimiter (DEL) marks the end of the ACK field

EOF: End of Frame

consists of seven consecutive recessive bits;

marks the end of the Data Frame;

IFS: Interframe space

consists of at least three consecutive recessive bits;

no transmission is allowed during the Interframe Space (IFS);

is needed by controllers to copy received frames from their Rx buffers


Data Link Layer: The message – Remote Frame

Remote frames: Destination node is able to require data from another node: RTR = 1

standard frame;

extended frame;


Data Link Layer: The message – Faults

Fault Types in a CAN Bus System:

Global Faults: lead to a breakdown of the system wide communication (e.g. short circuits or interrupts of the line, deadlock of the bus due to a permanent transmitting node;

Local Faults: are limited to malfunctions of a node ore node components (e.g. interrupts in a bus connector, transmit problems of a transmitter, etc.);

Temporary Faults: disturb the CAN bus system for a limited time;

Permanent Faults: disturb the CAN bus system all the time, they are not reversible.


Data Link Layer: The message – Error Frame

Error frames: Each CAN node detecting an transmission error sends an “Error Frame” (Sequence of 6 bit with the same level):

The bit actually appearing on the bus is different from the one transmitted

More than five bits of equal polarity inside of a frame are detected until the ACK field

CRC code calculated by receiver does not match received CRC code

Fixed-form bit field contains one ore more illegal bits. e. g. violation of end of frame EOF format, CRC- or ACK-delimiter

Acknowledge (ACK) bit is recessive

IFS/IDLE SOF Message ID Control Data ACK IDLECRC IFSEOF /SOF

Bit Error Monitoring Area Bit Error Monitoring Area Bit Error Stuffing Monitoring Area Bit Error Stuffing Monitoring Area


CRC Error Monitoring Area CRC Error Monitoring Area


Form Error Monitoring Area Form Error Monitoring Area


ACK Error Monitoring Area ACK Error Monitoring Area



Data Link Layer: Error Frame – Status of the node

For each detected error there is generated an active error flag (queue of six consecutive dominant bits)

The error management unit uses two error counters:

a receive error counter REC

a transmit error counter TEC

CAN node status after reset: TEC = REC = 0.

For each detected error there is generated an passive error flag (queue of six consecutive recessive bits)

If to many errors are detected by one node, this node is automatically disconnected from the bus.Error active node :

6 dominant bits

Error condition

Error passive node :

6 recessiv bits

Error condition

ErrorPassive

BusOff

ErrorActive

REC > 127 or

TEC > 127 REC < 128 andTEC < 128

TEC > 255

HW reset


Data Link Layer: Error Frame – Superposition of error flags

In the case of one node detects a local error it will send an error flag. Other nodes may detect an error because of this error flag. They send also an error flag;

After receiving/sending an error flag all nodes cancel the message;

Each node which detects an error increments its error counters;

Overlapping error flags result in a queue of 6 up to 12 active error bits followed by an error delimiter (queue of 8 recessive bits)

Error condition

Superpositionof Error Flags

Up to 6 biterror flagNode X

IFS

3 bitIFS

SOF / Idle

Bus Idle orStart of Frame

Error Flag

6 biterror flagNode A

8 Bit Error Delimiter

8 biterror delimiter

Node X


Data Link Layer: The message – Overload Frame

Unit sends Overload Frame when at present it cannot receive frames any more due to high workload;

Transmission of an Overload Frame is started during the first two bits of the Interframe Space (IFS) of the preceding frame;

Other units react immediately by also transmitting Overload Frames Overload Flags overlap, resulting in up to 12 consecutive dominant bits;

Implemented in very few (mostly older) controllers, though controllers must still be able to interpret correctly Overload Frames they receive;

Overload Frames do not influence the error counters (TEC and REC)

Overload FlagBus Idle

recessive

Overload Delimiter Interframe Space

Bus Idle

dominant3 bits Bus Idle6 dominant bitsBus Idle 8 recessive bits


Data Link Layer: Transmitter / Receiver

A unit originating a message is called “TRANSMITTER” of that message. The unit stays TRANSMITTER until the bus is idle or the unit loses ARBITRATION.

A unit is called “RECEIVER” of a message, if it is not TRANSMITTER of that message and the bus is not idle.

The message is valid for the transmitter, if there is no error until the end of END OF FRAME. If a message is corrupted, retransmission will follow automatically and according to prioritization. In order to be able to compete for bus access with other messages, retransmission has to start as soon as the bus is idle.

The message is valid for the receivers, if there is no error until the last but one bit of END OF FRAME.


SOFTWARE


CAN subsystem: Vector solution

Application LayerApplication Layer

Presentation LayerPresentation Layer

Session LayerSession Layer

Transport LayerTransport Layer

Network LayerNetwork Layer

Data Link LayerData Link Layer

Physical LayerPhysical Layer

ISO/OSI Model

CAN bus

CAN TransceiverCAN Transceiver

Application SoftwareApplication Software

CAN ControllerCAN Controller

CAN SubsystemCAN Subsystem

CCLIL

TP

DIAG

NMCalibr

CAN Driver

GENyTool


Data Link Layer: CAN driver

The generic CAN Driver code is independent of the Application.

Functional scope:

Initialize the CAN controller;

Transmit a single CAN message: CanTransmit(<MsgHandle>);

Receive a single CAN message;

Handle Bus-Off;

Support sleep mode;

Support special services.

A CAN controller is said to be in "bus off" state if it's not

participating in the bus traffic

Some CAN Controller are supporting a so called sleep mode with reduced power consumption.

1. Interrupt control;2. Assertions;3. Support OSEK;4. Multiple channels;5. ...


Generic precopy means that a common function ApplCanGenericPrecopy() is called for all identifiers.In case IL component is used the generic precopy is mandatory and it will be: IlCanGenericPrecopy()

Data Link Layer: CAN driver – Rx

HW Acceptance Filters

The function ApplCanMsgReceived() is called by the CAN Driver on every reception of a CAN message after the hardware acceptance filter is passed.

Receive Function

SW Acceptance Filters

DLC Check

For a Basic-CAN Controller or the Basic-CAN object of a Full-CAN Controller the hardware acceptance filtering provided by the CAN Controller is not sufficient. Therefore a software acceptance filtering has to be supported by comparing the incoming message identifierwith the complete list of all relevant message identifier. If a CAN message has passed the hardware acceptance filtering but is rejected by the software acceptance filtering (in case of a Basic CAN receive object) a special callback function will be called (if configured).

Generic PreCopy Function

PreCopy Function

Copy DATA in Rx Reg.

After the generic precopy (if configured) a precopy function separate for each message according to the entry in the description data is called.In the next step the data is copied to the global data buffer.

Indication Flag

Indication Function

Then the indication actions defined for this message are performed. This means the indication flag is set and/or the indication function is called. The Application has to reset the indication flag before or after data processing.

End Rx

CAN ISR

CAN message receivedCAN BUS

Normally, the CAN Driver is informed by the CAN Controller via interrupt of the reception of a CAN message.

That means the received CAN identifier has passed the hardware acceptance filtering of the CAN Controller and the entire message is stored in a receive register.

In case of a Basic-CAN object, the message has to be retrieved and processed as fast as possible.


Data Link Layer: CAN driver – Tx

Queue Message

PreTransmit Function

Copy DATA in Tx Reg.

Tx Observe

Confirmation Function/Flag

Check Queue

SW Appl: CanTransmit(msg)

Start Tx

End Tx

CAN ISR

Confirm Tx Observe

Common Confirmation Function

CAN BUS

First the CAN Driver checks whether the transmit path isswitched to online state. If not the function returns with an error code.

CAN Driver checks the availability of a hardware transmit object. If no object is available the transmit request is stored in the transmit queue.

Within this user specific function the Application maycopy the data to be transmitted directly to the CAN Controller hardware registers.

This functionality is used to check the transmit path of the CAN Driver.The prototypes for the functions 'ApplCanTxObjStart', 'ApplCanTxObjConfirmed', 'ApplCanInit' are generated.

A confirmation function for all messages is called: ApplCanTxConfirmation()

The message-specific confirmation function is called.Afterwards the confirmation flag is set.

If the CAN Driver is configured to use a transmit queue, after the processing the confirmation actions the CAN Driver checks whether the transmit queue is empty. If so the transmit interrupt routine is finished.

CAN online ?

no


Network Layer: Network Management (NM)

Functional scope:

Controls the transition to Sleep Mode;

enter the BusSleep mode simultaneously;

Determine and monitor the Network Configuration;

network nodes that are currently active;

Provide status information of the NM node and the network itself;

Bus Off Handling and Recovery;

Interaction with CAN driver;

Multiple ECUs

Multiple ECUs are control units which are assembled several times within the CAN network with the same software. Example: Seat in the front on the left hand side and on the right hand side

The NM ensures that all active ECUs within a network will enter the BusSleep mode simultaneously.This is required because an ECU will be woken up by any message on the CAN bus. That is the reason why a transition of a single ECU into the BusSleep mode only makes sense, if all the other ECUs are also ready for BusSleep mode and will not send further messages.NM decides when the CAN channel must be activated or deactivated.


Network Layer: OSEK Network Management (OSEK-NM)

Direct node monitoring requires a network-wide synchronization of NM messages. For this purpose a logical ring is used. In a logical ring the communication sequence is defined independently from the network structure. Therefore each node is assigned a logical successor.

Address related communication has to take into account receiver and emitter. Each node has a unique identification which is known in the network.

The network can enter different states like: NMOff, NMOn( NMAwake, NMBusSleep, NMActive ), NMShutDown

Node D1 Node E1 Node A- two logical nodes -

Node C1 Node B1 Node C2

Node B2

D1 -> E1 E1 -> A

A -> B1

B1 -> C1

C1 -> D1

A -> B2

B2 -> C2

C2 -> A

CAN 0 CAN 1

logical predecessor message

logical successor message


Transport Layer: Transport Protocol (TP)

A TP is needed if the data length exceeds 8 bytes. In this case, the sender must divide up the data into a number of CAN messages with the same identifier. Additional information is necessary for the recipient to put the data back together again.

Functional scope:

Message construction: unsegmented / segmented;

Addressing modes: normal / extended / normal fixed / mixt;

TP classes: single / static multi / dynamic multi;

Error detection;

e.g.: ISO 15765, SAE j1939, Bosch McNet...

The CAN ID contains the complete addressing information (to each source and target address combination a unique CAN ID is assigned)

The receiver is informed of the length of the whole message in the First Frame by the sender. The receiver answers with a Flow Control. The receiver gives the Block Size and the Separation Time to the sender in this Flow Control. The sender transmits the maximum Block Size Consecutive Frames after the reception of the Flow Control. The receiver does not answer it with a Flow Control, if all data has been transmitted.

Unsegmented messages are transmitted by a Single Frame message. Single Frame messages can have a length of 7 data bytes at a maximum (normal addressing) respectively 6 data bytes (extended addressing). There is no Flow-Control.

The CAN ID contains only the source address and the first data byte contains the target addressing information.

The extended CAN ID contains the complete addressing information according J1939

Additionally to the extended CAN ID, according J1939, the first data byte contains a second target address information. Since ISO15765-2: 2003 the additional addressing mode mixed addressing on 11-bit CAN IDs is defined. The address extension is stored in the first byte followed by the TPCI information.

In a Single TP class only one connection is possible, which is using the only available TpChannel.

While using Static TP classes every connection is fixed assigned to a TpChannel

The idea of dynamic TP classes is to use the circumstances that not all connections are used at the same time. Therefore a connection is necessary allocating a TpChannel at run-time.

- single frame;- first frame;- flow control;- consecutive frame;- DLC.


Presentation / Session Layer: Interaction Layer (IL)

Functional scope:

Interface between application layer and data link layer;

Access macros and functions;

Guarantees the consistency of any transmitted or received data and relieves the application of this area of responsibility;

Multiple channel support;

Receive messages:

Signal oriented access to data: signal value, indication, firstvalue, data changed, timeout.

Transmit messages:

Signal oriented access to data to be sent;

Tx modes for signals and messages (e.g. cyclic, on request, if active);

Notification: confirmation, timeout.


Communication Control Layer (CCL)

The Communication Control Layer component is designed to simplify the use of the CAN in ECU’s by covering all CAN communication components like CAN Driver, Interaction Layer, Network Management, Transport Protocol etc..

Now the application has a simplified and smaller API to handle the CANbedded components (e.g. initialization, task handling, transceiver handling, network management handling etc.).

main integration interface


Generation Process Tools: GENy; CANdrGen

(GENy) Static files

(GENy) Configuration

CAN data base

(GENy) SW Tool

(GENy) Generated files

Own ECU

All the above parameterization is considered here: CCL, IL, NM, TP etc.

The .dbc file normally is designed by the vehicle manufacturer and distributed to all suppliers that develop an ECU. It contains information about all CANbedded components (e.g. network management type, messages and signals etc.). Every supplier uses the SAME dbc file for one type of vehicle to guarantee a common basis for development.

SW Application

SW Project

A Windows program were you configure the Software Components of CANbedded. GENy generates configuration files for each software component

Truck

other ECU

other ECU

These file are the output of the execution of the generation tool. They are reflecting the project specific configuration.

These files are available together with the tool directly from the tool supplier (Vector). These files will remain unchanged and are independent from the project specific configuration.

Other project related files

Compiled and linked project which will be loaded into the ECU

HW, SW and Mechanical ECU.


HIGH LEVEL PROTOCOLS


j1939 standard

The particular characteristics of J1939 are:

29-bit identifier;

Peer-to-peer and broadcast communication;

Transport protocols for up to 1785 data bytes;

Network management;

Definition of parameter groups.

Interpretation of the CAN Identifier

PDU = Protocol Data Unit

Prio3 bits

Rez1 bit0x0

Data page1 bit

PDU Format8 bits

PDU Specific8 bits

Source Address8 bits


j1939: PGN

Parameter groups

Parameter groups combine similar or associated signals. In the specification SAE J1939-71 the parameter groups are defined with the signals they contain.

Global PGNs for parameter groups that are sent to all (broadcast). Here all 16 bits of the PGN are used; the value of the upper 8 bits (PDU format) must be greater than 239 (0xF0);

Specific PGNs for parameter groups that are sent to particular devices (peer-to-peer). With these PGNs, only the higher-value 8 bits (PDU format) are valid and the value must be smaller than 240. The lower value byte (PDU specific) is always 0.

Each parameter group is addressed uniquely via a number (Parameter Group Number): PGN = DP + PDUF + PDUS

Sample of a parameter group definition:Name: Engine temperatureTransmission rate: 1 sData length: 8 bytesData page: 0PDU format: 254PDU specific: 238Default priority: 6PG Number: 65262 (FEEE16)Description of data:Byte: 1 Engine coolant temperature

2 Fuel temperature3,4 Engine oil temperature5,6 Turbo oil temperature7 Engine intercooler temperature8 Not defined


j1939: NM

Network management:

On a J1939 network, each device has a unique address. Each message that is sent by a device contains this source address. There are 255 possible addresses:

0..253 – Valid addresses of an ECU

254 – Zero

255 – Global


j1939: BAM + DT

For broadcast transmission, the BAM (Broadcast Announce Message) protocol is used. Here, after a BAM-PG the transmitter sends all data PGs at a minimum interval of 50ms.


j1939: BAM + DT

1st message: BAM (Broadcast Announce Message) -> data field

2nd message: DT (Data Transfer) -> data field

Control Byte0x20

Byte Size2 Bytes

No. of Packets1 Byte

Rez0xFF

PGN3 Bytes

Sequence Number1 Byte

Data7 Bytes

- - -

last message frame: DT (Data Transfer) -> data field

Sequence Number1 Byte

Datan Bytes

Reserved: 7-n Bytes0xFF


TESTING


Simulation: CANoe, CANalyzer

Own ECU

Truck

other ECU

other ECU

During development of own ECU the rest of the CAN network nodes (the truck with the other ECUs) might not be available.

(CANoe) PC simulation

Simulated ECU

Simulated ECU

For development, testing and analysis purposes a (CANoe) simulation that runs on PC will simulate the behavior of the rest of the network. This simulation must be as accurate as possible in order to avoid the appearance of differences between the simulated network and the physical network.

In this simulation the tester can send and receive messages from the data base and observe the behavior of his ECU.

In the simulated CAN network and the physical CAN network the same CAN data base will be used (dbc).The CAN subsystem software will also be the same in both cases.

CAPL (CAN Application Programming Language) programmed:-timers;-reaction at messages;-reaction at keyboard;-environment variables...

CANoe features:-simulated network nodes;-normal and interactive generator blocks;-replay blocks;-interface panels;-trace windows, filters and logs;-statistics, graphs ...


CANoe: Simulation setup window

Generator Block:- can output frames: data, remote, error- can be triggered via key press, time arrival of another message- can interact with the CAN data base

Interactive Generator Block:- can output frames: data, remote, error- can be triggered via key press, time- can manipulate during simulation runtime- can display and manipulate signals inside message

Network Node:- can be programmed in CAPL language in order to interact in all aspects with the CAN bus- can interact with the CAN data base

Replay Block:- can output messages that are stored in a log file ( e.g.: CANOE.asc file)

Simulated CAN bus- can be switched to real time mode

Associated CAN data base


CANoe: Measurement windowStatistics window:- can graphically show the bus load with data and error frames

Bus statistics window:- can show the bus load with data and error frames- can show the CANoe error state: active, passive, bus off

Trace window:- shows the content of the bus: timing, channels, message ID, name, direction, length and data field

Data window:- shows the values of various CAN signals in raw value or/and physical value

Graphics window:- shows graphically the values of various CAN signals in raw value or/and physical value

Logging window:- allows the user to record the content of the CAN bus into a log file

Filters:- all windows can have applied filters: pass filter, stop filter, channel filter


CAN data baseECU configuration:-source address;-received and transmitted messages and signals

Message configuration:- ID, name, length, receiving and transmitting ECU, signal layout, transmission type and cycle time- etc;

message list

signal list

CAN channel name

Signal configuration:- length, bit ordering, unit, factor, offset, min and max, send type, timeout time, receiving ECUs, - etc.


CANoe: Hardware configuration

Channel information:-hardware equipment for connecting to CAN bus;-baudrate;-CAN controller and transceiver used

Channel synchronization configuration:-baudrate-bit timing settings


Vector Hardware Configuration: Windows driver

The Vector Hardware Configuration utility enables you to configure installed Vector hardware. Besides the real hardware items in the tree view, two virtual (simulated) CAN channels for testing purpose (Vector applications) are available. For this purposes no hardware is necessary.

Each hardware channel can be configured to work together with different applications like CANoe and CANalyzer depending on the purchased license.

Vector Hardware Driver can be found in Windows Control Panel


LITERATURE

ISO 11519 - Road vehicles — Low-speed serial data communication

ISO 11898 - Road vehicles — Controller area network (CAN);

ISO 11992 - Road vehicles — Interchange of digital information on electrical connections between towing and towed vehicles;

ISO 14229 - Road vehicles — Unified diagnostic services (UDS) - Specification and requirements;

ISO 14230 - Road vehicles — Diagnostic systems - Keyword Protocol 2000;

ISO 15765 - Road vehicles — Diagnostics on Controller Area Networks (CAN);

ISO 16845 - Road vehicles — Controller area network (CAN) - Conformance test plan;

SAE j1939 - Recommended Practice for a Serial Control and Communications Vehicle Network;

http://www.semiconductors.bosch.de/en/20/can/index.asp

http://www.vector-informatik.com/vi_index_en,,9656.html

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