HMS has now extended the functionality of the 1SI CANopen module for the SIMATIC ET200S I/O system module with the integration of Transparent CAN 2.0A.
With this new functionality, the 1 SI CANopen module allows transmission of any CAN frame from the PLC regardless of the overlaying CAN protocol and is capable of receiving a number of pre-defined CAN frames from the CAN network.
CAN 2.0A is the underlying protocol of many fieldbus protocols, CANopen being one of them. When the application disables CANopen functionality, it still retains access to this protocol. CANopen can be disabled at any time, but if the user wants to re-enable CANopen functionality, the 1 SI CANopen module has to be restarted.
HMS provides new PLC function blocks for this functionality, that gives the designer of the PLC program the possibility to interpret/generate any CAN frame directly in the PLC program and thereby making it possible to implement customer specific protocols. Furthermore, it is now also possible for the user to connect nodes that only support customer specific CAN protocols to the Profibus or Profinet network.
When CANopen functionality is disabled, the only functionality available is the transmitting and receiving of CAN data frames on the bus. The frames are tagged with an identifier. Only messages with an identifier specified during setup will be forwarded to the PLC. The data in the frame is then available for the user to interpret. When sending a frame, the user specifies the data and adds a valid identifier before sending it to the module.
Transparent CAN 2.0A Features
• Possibility to implement any custom CAN based protocol on the slave side, which is controlled by the PLC
• Special PLC function block available for easy integration in to Step 7
• The 1SI CANopen module functions in a transparent pass-through mode when handling a custom CAN protocol
• Ability to transmit and receive CAN frames in the PLC program
• Supports only the CAN 2.0A standard
• Selectable baud rate from 20 kbit/s – 1 Mbit/s
• CANopen functionality is disabled when the transparent CAN mode is used