CAN Bus Wiring, CAN Bus Termination

 

Common mode voltage in CAN bus

If the CAN bus contains devices with CAN bus interfaces that are not isolated from the power supply (i.e. the I/O communication module BPlus available from MOTORTECH or the NOX sensor from the CAN bus/NOX sensor module), error-free communication of the devices in the CAN bus is only guaranteed if the voltage levels of the signal lines CAN Hi and CAN Lo are within the range of –2 V to +7 V. If this common mode voltage range is not maintained, use a CAN bus insulator (available from MOTORTECH as accessory) for potential isolation between the interfaces.

  

For wiring, use a terminal strip in the control cabinet. On the left relay connector of the I/O communication module BPlus (see position 1 in section Assignment), the white wire CAN Hi and the brown wire CAN Lo are used for the CAN connection to the previous device in the CANopen® network. Use the yellow wire CAN Hi and the green wire CAN Lo of the left relay connector to connect the I/O communication module to the following device in the CANopen® network. If the I/O communication module is the last device in the CANopen® network, connect the supplied 120 Ω terminating resistor to these wires.

Reference ground of the CAN bus interface of the I/O communication module BPlus is the supply voltage ground.

On the EasyNOₓ side, connect the shield of the CAN cable to the Shield terminal in the EasyNOₓ. On the module side, connect the shield of the CAN cable to the earth of the control cabinet for each I/O communication module BPlus. Connect the shields of the CAN cables of all devices in the CAN bus with each other.