Festo EMCA-EC-67 CO Series, Описание

Страница: 25 / 416

2 CANopen
Festo – EMCA-EC-C-HP-EN – 2017-11e – English 25
2.2.4 CAN bus cabling
The CAN bus offers a simple, interference-resistant method of networking all the components of a sys­
tem together. A requirement for this is that all of the subsequent instructions on cabling are observed.
120
Ω
120
Ω
CAN shield
CAN-GND
CAN-L
CAN-H
CAN shield
CAN-GND
CAN-L
CAN-H
CAN shield
CAN-GND
CAN-L
CAN-H
Bus length
End participant End participant Participant
Fig. 2.3 Cabling example
– The individual nodes of the CAN bus network are connected in series. The CAN bus signals are
passed from component to component through the CAN bus cable
è
Fig. 2.3.
– Both end participants of the CAN bus network must be terminated with a terminating resist­
or (120 Ω, ±5 %). Observe the information and notes on this in the corresponding documentation of
the end participants.
– Screened cable with 2 twisted conductor pairs must be used for the CAN bus wiring
è
Tab. 2.5. The
first twisted conductor pair is used for the CAN signals CAN-H and CAN-L. The second twisted con­
ductor pair is used for the load CAN-GND (reference potential for CAN signals). The screening of the
CAN bus cable must be connected to the CAN shield port at each node.
– The use of adapters is not recommended for CAN bus cabling. If despite this an adapter is used, a
plug connector with metal housing is recommended. For plug connectors with a plastic or metal
housing, ensure that the screening of the CAN bus cable is connected properly.
– To keep the disturbance coupling as low as possible, CAN bus cables should not be laid parallel to
supply cables (e.g. motor cables). In addition, supply cables with screening must be earthed cor­
rectly.
– To construct an interference-free CAN bus cabling, observe the information and notes in the Control­
ler Area Network protocol specification, version 2.0, issue 1991, of Robert Bosch GmbH.