Wiring CANopen® Network (CAN1)

The CAN bus interface CAN1 of the EasyNOₓ connects the EasyNOₓ to a CANopen® network. Via this CANopen® network, you connect the EasyNOₓ to the following devices:

Observe the device restrictions in the section Adding a Device.

The EasyNOₓ functions as NMT manager 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 cable 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. Only use shielded CAN cables in compliance with the standards ISO 11898-2 and CiA® 303-1.

The EasyNOₓ has a built-in 120 Ω terminating resistor and must therefore be the first or last device in the CANopen® network. The following diagram shows as an example the wiring of the EasyNOₓ with other devices:

 

EasyNOₓ

Second device

Second-to-last device

900_Abmessungen_EasyNOx-in-Gehäuse

 

Third device

Last device

  

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.

   

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 cable length depends on the bit rate:

Bit rate

Maximum cable 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.
  • Comply with the standards ISO 11898-1 and CiA® 303-1.

   

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