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. The EasyNOₓ has a built-in 120 Ω terminating resistor and must therefore be the first or last device in the CANopen® network.
Only use shielded CAN cables in compliance with the standards ISO 11898-2 and CiA® 303-1. The shield must be connected across the entire bus cable. To avoid ground loops, the shield is to be grounded at only one point, e.g. via the Shield terminal of the CAN bus interface CAN 1 at the EasyNOₓ (see section Wiring). If only bus segments are shielded, every bus segment must be grounded at one point each.
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First device |
Second-to-last device |
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Second 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:
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The EasyNOₓ is delivered with a bit rate set to 250 kbit/s.
Settings on the Devices
All connected devices are designated 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 EasyNOₓ. Refer to the operating manuals of the respective devices for instructions on how to set the node ID for 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 EasyNOₓ. Observe that the node IDs of the I/O communication modules BPlus are firmly preset (see section Device Setup EasyNOₓ).
Overview of the CAN bus Setting up the CAN bus in the CANopen® network requires the following settings:
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CANopen® protocol If you require information on the CANopen® protocol of your EasyNOₓ, contact your MOTORTECH contact person (see section Customer Service Information). |