The CAN bus interface CAN1 of the EasyNOₓ connects the EasyNOₓ to a CANopen® network. This CANopen® network is used to connect the EasyNOₓ to an optional I/O communication module and other devices supported by the EasyNOₓ. The EasyNOₓ functions as NMT master in the CANopen® network.
The wiring of the CAN bus requires three conductors (CAN Hi, CAN Lo, and CAN Com). The conductors for CAN Hi and CAN Lo must be twisted wires. At a bit rate of 250 kbit/s, the bus may only have a maximum wire length of 250 m (820') and must be terminated at both ends by a terminating resistor of 120 Ω between the CAN Hi and CAN Lo conductors to prevent reflections. Use shielded CAN cables only.
The EasyNOₓ has a built-in 120 W terminating resistor and must therefore be the first device in the CANopen® network. The following diagram shows as an example the wiring of the EasyNOₓ with four other devices:
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EasyNOₓ |
Second device |
Second-to-last device |
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Third device |
Last device |
Common mode voltage in CAN bus Error-free communication of the devices on 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. |
CAN bus wiring Note the following when connecting the CAN bus:
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The EasyNOₓ is delivered with a bit rate set to 250 kbit/s.