CAN bus. Controller Area Network (CAN) is a broadcast, differential serial bus standard, originally developed in the 1980s by Robert Bosch GmbH, for connecting.

CAN bus

神戸大学　金子　敬宏

Controller Area Network (CAN) is a broadcast, differential serial bus standard, originally developed in the 1980s by Robert Bosch GmbH, for connecting electronic control units (ECUs).

CAN was specifically designed to be robust in electromagnetically noisy environments and can utilize a differential balanced line like RS-485.

It can be even more robust against noise if twisted pair wire is used. Although initially created for automotive purposes (as a vehicle bus), nowadays it is used in many embedded control applications (e.g., industrial) that may be subject to noise.

Bit rates up to 1 Mbit/s are possible at network lengths below 40 m. Decreasing the bit rate allows longer network distances (e.g. 125 kbit/s at 500 m).

The CAN data link layer protocol is standardized in ISO 11898-1 (2003).

This standard describes mainly the data link layer — composed of the Logical Link Control (LLC) sublayer and the Media Access Control (MAC) sublayer — and some aspects of the physical layer of the OSI Reference Model.

All the other protocol layers are left to the network designer's choice.

CAN： Controller Area Network

伝送方式：半二重シリアル通信

1つの伝送路を用いて送信と受信を切り替えながら行う通信方法

Network Topology：バス型－マルチマスタ

　バスがあいているときは、バスに接続されるすべてのユニットがメッセージの送信を始めることができる

アクセス制御方式： CSMA/NBA

　早く通信を始めた局が通信を続ける優先権を持つ

　同時に２つの通信を始めるユニットが２つあった場合、通信フレームの始め　の１１ビットのパターンをお互いに見合って優先権得たユニットが通信を続ける

　 CSMA/CDの場合は同時の時一時中断

最大通信速度：１Mbps（）

ECU

device

I/O

device ECU

I/O

device

device

CAN

NI PCI-CAN/2Operationg System

Windows 2000/NT/XP/Me/98

LabVIEW Real-Time

Recommended Software

LabVEIW

Lab Windows/CVI

Other Compatible Software

C/C++

Visual Basic 6

Application Software (included)

Bus monitor utility

Driver Software (included)

NI-CAN

ESD CAN-CBX-AI814

・ CANopen module with In-Rail-Bus

・ 8 A/D-converter inputs

・ resolution 14 bit

・ input voltage range

・ CANopen

Monitoring system for the HCAL prototype

• LED monitoring system- System concept- Choice of LED- Test of fiber bundle- LED driver studies

• Temperature monitoring • Slow control

Slow ControlTo intervene on detector parameters frontend processors (mostly VME) and interfaces can be addressed via a dedicated slow control bus connected to the monitoring workstation.

As bus systems two options are considered at present:

CANbus is a standard slow control bus which is widely used in the VME sector. It also offers accessibility to crates and power supplies allowing additional monitoring and maintenance possibilities.

Ethernet as slow control bus is an inexpensive alternative. Most VME CPUs are equipped with standard ethernet interfaces. The protocol is more flexible and allows a higher bandwidth then CANbus. To avoid problems this net should be separated from the CERN wide network

The slow control processors perform e.g. voltage and temperature checks, set voltages and thresholds.

Plan

Gain monitoring systemにおける PCへの接続