Overview

The CAN protocol (Controller Area Network) is specified in the proposed international standard ISO DIS 11 898 whereby only the electrical parts of the Physical Layer and the Data Link Layer (Layers 1 and 2 in the ISO/OSI Layer reference model). The CiA (CAN in Automation, an international user's and manufacturer's association) has defined implementation as an industrial fieldbus with the DS 102-1 recommendations for bus coupling and the bus medium.

• The CBC board complied with the definitions in ISO-DIS 11 898 and in DS 102-1.
• The CBC board only supports CAN Layers 1 and 2. Higher-level additional communication definitions of the various user organizations, such as CAN open of the CiA are not currently supported (CAN open on request).

The CBC (Communication Board CAN) facilitates communication between SIMOREG converters and a higher-level automation system, between SIMOREG converters and between SIMOREG converters and other field devices by means of the CAN protocol. The board is supplied with power via the basic unit.

The CBC board is limited to the main specifications of CAN and is therefore free of the dependent specifications of the user organizations. Data is exchanged with SIMOREG in accordance with the useful data definition for drive technology with PROFIBUS-DP:

The useful data structure is subdivided into two areas

• Process data (control words, setpoints, status words and actual values)
• Parameter area (mechanism for reading and writing parameter values, e. g. setting values, warnings, fault numbers or fault values

The useful data are transferred in the form of communication objects (identifiers).

Individual communication objects are defined for the process data to and from the drive as well as for the “write” and “read” parameter tasks.

The CAN protocol supports high-speed data transfer between bus stations. In the case of useful data transfer, a distinction is made between the parameter ID value (PKW) and the process data (PZD).

A CAN data message frame comprises the protocol header, the CAN identifier (up to 8 bytes of useful data) and the protocol trailer. The CAN identifier serves to uniquely identify the data message frame. In Standard Message Format, up to 2048 different CAN identifiers are possible; in Extended Message Format, 229 CAN identifiers are possible. Extended Message Format is tolerated by the CBC board but not evaluated. The CAN identifier specifies the priority of the data message frame. The lower the number of the CAN identifier, the higher the priority of the message frame.

X458 and X459 connectors on the CBC board

The CBC communication board has one 9-pin Sub-D plug (X458) and one 9-pin Sub-D socket (X459) for connection to CAN.

The pin assignments and internal connections of the connectors are identical. The connector interface is short-circuit proof and floating.

Fitting the CBC board

One LBA and one ADB are needed for installing the board.

Up to 8 bytes of useful data can be transferred in a CAN data message frame. The PKW area always comprises 4 words or 8 bytes i. e. the data can be transferred in a single data message frame. In the case of SIMOREG 6RA70, for example, the process data area comprises 16 words, so 4 data message frames are required in total to transfer all the process data.