Network safety standard: European standard EN 50325-5
The CANopen Safety protocol (CiA 304) developed by CAN in Automation (CiA), international users’ and manufacturers group, is published as an European standard and available as EN 50325–5 from the European Committee for Electrotechnical Standardization (CENELEC) and any National body, CiA announced from Nuremberg, Germany on Sept. 9. The CANopen Safety protocol is an addition to the CANopen protocol standardized in EN 50325–4, also known as CiA 301.
CANopen Safety is designed to allow safety-related communication based on CAN according to IEC/EN 61508. The German TÜV has approved the protocol for use for systems requiring Safety Integrity Level 3 (SIL 3). Safety-related devices use the Safety-related Data Object (SRDO) service, which allows one-to-many communication relations. The SRDO messages are periodically broadcast in the network and any other safety-related device interested in the data can use it without the need of a centralized master. An SRDO consists of two CAN messages where the first CAN message contains the regular data and second CAN message is transmitted on a different identifier with the data content bit-wise inverted. This makes the protocol very efficient as it allows the use of small and cheap micro-controllers as no complicated CRC is used, CiA said.
The first ready-to-use implementations of CANopen Safety are available: The TÜV approved CANopen Safety Chip (CSC02) available from CiA implements the CANopen Safety protocol in a single chip.
The CSC02 allows easy integration of the CANopen Safety protocol into safety-related devices. The first commercial product available that uses the CSC02 is the safety-related encoder family by Posital.
CAN in Automation
– Also read:
– Mark T. Hoske, Control Engineering, www.controleng.com, CFE Media, www.cfemedia.com.