CAN bus wiring

General Information on CAN Bus Wiring

The wiring of the CAN bus requires the three conductors: (CAN High, CAN Low und CAN Ground). The conductors for CAN high and CAN low must be twisted wires. The bus may only have a maximum wire length of 250 m (820 ft) and must be connected on both ends by a terminating resistor of 120 Ω between the CAN High and CAN Low wires, to prevent reflections.

The diagram shows an example of the wiring for four devices:

 

First device

Second-to-last device

CAN-Bus

 

Second device

Last device

 

CAN bus wiring

Note the following when connecting the CAN bus:

  • A maximum of 110 devices can be connected to a CAN bus.
  • The maximum wire length is 250 m (820') depending on the transfer rate.
  • Each bus end must be fitted with a terminating resistor of 120 Ω (see drawing).

   

Settings on the Devices

All connected devices are referred to as nodes on the CAN bus. Each node is identified by a CANopen node ID. These node numbers must be indicated both in the connected devices as well as in the configuration of the PowerView3. Refer to the operating manuals for the respective devices for instructions on how to set the node ID on each device and to determine if further settings must be made to communicate via the CAN bus.

A node ID can only be assigned once within a CAN bus and must be a number between 1 and 127. Note that some devices use several node numbers. The node numbers must be assigned in the configuration after start-up of the PowerView3.

 

Overview of the CAN bus

Setting up the CAN field bus requires the following settings:

  • Activate CAN interface on the devices if applicable.
  • Assign unique CANopen node IDs to the devices.
  • Set transfer rate of all devices to 250 kBit/s

 

CANopen protocol

If you require information on the CANopen protocol, contact your MOTORTECH contact person.