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3.6 Diagnostics and Maintenance

3.6.1 No communication

The RX/TX LEDs on the CAN card in the Safety Simplifier show whether there is activity on the bus:

  • If TX, RX, or both are dimly lit, communication is active.
  • If either LED flashes very bright for a short time and then stays off for about 2 seconds, the bus is incorrectly installed (BUS OFF).

If communication cannot be established:

  • Make sure the termination resistors are correct (see 3.4.2 CAN card connection).
  • Make sure the CAN-H and CAN-L wires are connected to H and L respectively in all nodes on the CAN bus.
  • Make sure all nodes in the network have the same network settings (baud rate, cycle time and timeout). This is especially important for SimpleCAN networks that include several different Simplifier networks (different projects).

3.6.2 Online mode

SimpleCAN can be diagnosed with Online Mode in Simplifier Manager, where the state of each bit can be viewed live in the logic diagram.

You can go online either wirelessly via the Simplifier Monitor stick, or via USB directly to the Safety Simplifier.

Online mode showing SimpleCAN Transmit and Receive blocks with live bit states and Link OK blocks

SimpleCAN blocks in online mode.