Cabling Instructions - Festo CiA 402 Manual

2 CANopen
Termination
A terminating resistor (120 Ω) can, if required, be switched by means of DIL switch [S1.12] on the basic
unit.
2.2.4

Cabling instructions

The CAN bus offers a simple, fail-safe ability to network all the components of a system together. But a
requirement for this is that all of the following instructions on cabling are observed.
CAN shield
CAN-GND
CAN-L
CAN-H
120 Ω
Fig. 2.1 Cabling example
– The individual network nodes are basically connected in series, so that the CAN cable passes from
motor controller to motor controller (
– At both ends of the CAN cable, there must be available a terminating resistor of exactly 120 Ω ± 5 %.
Such a terminating resistor is often already integrated into CAN cards or PLCs, which must be taken
into account correspondingly.
– A screened cable with precisely two twisted conductor pairs must be used for the cabling
Tab. 2.3. One twisted pair is used for connecting CAN-H and CAN-L. The conductors of the other
pair are used together for CAN-GND. The cable screening is connected to the CAN shield connection
at all nodes.
– The use of adapters is not recommended for CAN bus cabling. If this is unavoidable, then metallic
plug housings should be used to connect the cable screening.
– To keep the disturbance coupling as low as possible, motor cables should not be laid parallel to
signal lines. Motor cables must conform to specifications. Motor cables must be correctly shielded
and earthed.
– For additional information on the configuration of trouble free CAN bus cabling, refer to the Control-
ler Area Network protocol specification, version 2.0 from Robert Bosch GmbH, 1991.
Feature
Wire pairs
Core cross section
Screening
Loop resistance
Surge impedance
Tab. 2.3 Technical data, CAN bus cable
12
CAN shield
CAN-GND
CAN-L
CAN-H
Fig. 2.1).
Value
– 2
2
[mm ] 0.22
– yes
[Ω/m] 0.2
[Ω] 100 ... 120
Festo – GDCP-CMMS/D-C-CO-EN – 1404NH – English
CAN shield
CAN-GND
CAN-L
CAN-H
120 Ω