CAN Bus Wiring CAN1

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:

 

EasyNOₓ

Second device

Second-to-last device

0937_can-bus-verkabelung

 

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:

  • Each bus end must be fitted with a terminating resistor of 120 Ω (see drawing).
  • The maximum wire length depends on the bit rate:

Bit rate

Maximum wire length

Maximum length of a stub

Maximum length of all stubs

1 Mbit/s

25 m (82')

1.5 m (5')

7.5 m (25')

800 kbit/s

50 m (164')

2.5 m (8')

12.5 m (41')

500 kbit/s

100 m (328')

5.5 m (18')

27.5 m (90')

250 kbit/s

250 m (820')

11 m (36')

55 m (180')

125 kbit/s

500 m (1,640')

22 m (72')

110 m (360')

50 kbit/s

1,000 m (3,280')

55 m (180')

275 m (902')

 

  • Only use cables that are specified by the manufacturer for use in the CAN bus.

   

The EasyNOₓ is delivered with a bit rate set to 250 kbit/s.