Safely on the move in the CAN network

TR Electronic supplies proven safety encoders with CANopen safety interface.

Interfaces have always been the specialty of the Trossingen-based innovation company for absolute position detection. It was therefore only a matter of time (and market requirements) before the proven SIL encoders of the CD_582+FS series also became available with the CANopen Safety interface. The underlying CAN interface is a real veteran in automation, considering the Ethernet-based connections with PROFINET/PROFIsafe, Ethernet/IP with CIP Safety™, FSoE (FailSafe over EtherCAT) and Ethernet Powerlink / openSAFETY that have been implemented to date.

Unlike these interfaces, CANopen Safety works according to the “white channel principle”, i.e. in the safety assessment of the overall application, the entire signal path must prove its reliability. This is done, among other things, by repeating transmissions and using the underlying CSMA/CA (Collision Avoidance) protocol, which forms the basis of all CAN implementations.

The interface connection of the TR encoder has proven its reliability through extensive in-house tests, and the scanning technology is tried and tested, as with all CD_582+FS. This modular system is based on the latest technology and enables encoders from the standard portfolio to be perfectly adapted to the application. Mechanical connections are available via solid shaft, hollow shaft (blind hole shaft) and through hollow shaft. The shaft diameters vary up to 14 mm for solid shafts and 15 mm for hollow and blind hole shafts. As required for safety-related measuring systems, the positive locking of the drive shaft is secured by a keyway-keyway connection, and there is even a SIL-compliant torque support made of spring steel for the hollow and blind hole shafts.

Some of the features in the CD_582+FS with CANopen Safety have not yet been available on the market for these compact safety encoders.

This means that these encoders can also preset the position value without the axis having to be at a standstill. This “preset on the fly” works like electronic referencing - on request, the output value is adjusted to the previously stored preset value.

Error detection, such as device failure, is generally indicated in CANopen Safety by the controller reacting to the absence of communication protocols. The CD_582+FS also have an active fail-safe state, i.e. they can actively report an occurring error to the controller. The controller can react more quickly (without waiting for the monitoring time to expire): If a measuring channel is still available, the control unit can use the position value determined on one channel to move to a parking position, for example.

Degrees of freedom are also available in the scanning technology, with which the measuring system can be specifically adapted to the requirements. Whether fully magnetic sensing or with the fast, high-resolution sensing of optical position detection, the encoders are available for applications in accordance with SIL2/PLd or SIL3/PLe. There is a special feature for the devices with optical scanning as an option: In addition to the safe bus system, the position value is also output via an SSI or incremental interface (not safety-related). This additional interface can be used, for example, to supply subordinate control loops without having to go via the control system. At the same time, the encoder supplies the direct measured values without additional protection via the “gray” channel in the standard protocol.

Detailed technical data, instructions and the safety-related characteristic values for direct import into standard planning and design tools can be found on the TR Electronic homepage. As a special service, the EPLAN macros for all versions can also be downloaded directly from the homepage. The CD_582+FS SIL encoders from TR Electronic and especially the new CANopen Safety make the decision for safety-related encoders very easy: Same installation space, considerably higher safety. This is currently only available from TR Electronic with this wide range of variants.

All CD_582+FS with CANopen Safety Interface: https://www.tr-electronic.com/s/S025967

Press article including photograph