Correct Wiring of Electrically Isolated CAN Networks
6.2.2 Device Cabling
Attention:
If single shielded
double
twisted pair cables are used, realize the T-connections by
means of connectors that support connection of two CAN cables at one connector
where the cable’s shield is looped through e.g. DSUB9 connector from ERNI (ERBIC
CAN BUS MAX, order no.:154039).
The usage of esd’s T-connector type C.1311.03 is not recommended for single
shielded
double
twisted pair cables because the shield potential of the conductive
DSUB housing is not looped through this T-connector type.
If a mixed application of single twisted and double twisted cables is unavoidable, take
care that the CAN_GND line is not interrupted!
Figure 7:
Example of proper wiring with single shielded double twisted pair cables
6.2.3 Termination
●
A termination resistor has to be connected at both ends of the CAN bus.
If an integrated CAN termination resistor which is equipped at the CAN interface at the end
of the bus is connected, this one has to be used for termination instead of an external CAN
termination plug.
●
9-pin DSUB-termination connectors with integrated termination resistor and male and
female contacts (gender changer) are available from esd (order no. C.1303.01).
●
9-pin DSUB-connectors with integrated switchable termination resistor can be ordered e.g.
from ERNI (ERBIC CAN BUS MAX, female contacts, order no.:154039).
CAN-PCI/331
Hardware Manual • Doc. No.: C.2020.21 / Rev. 1.6
Page 17 of 27
CAN_L
CAN_GND
CAN_H
FE
CAN-CBX-DIO8
l
< 0,3 m
CAN-CBX-DIO8
l
< 0,3 m
CAN-DP/2
l
< 0,3 m
CAN_GND connected
to functional earth (FE)
at exactly one point
Net 2
Net 1
CAN Board
termination
switched OFF
CAN T-Connector
(DSUB9 connector, female),
with switchable termination
CAN
T-Connector
connected to earth (FE)
via computer housing
termination
switched OFF
CAN
T-Connector
termination
switched
ON
Attention:
Watch for the correct position of the
termination switches at the connectors!
CAN
T-Connector
e.g.
CAN-PCIe/402,
PMC-CAN/400,
CAN-USB/2, etc.
Female Connector
Male Connector
Termination connector "CAN-Termination-DSUB"
with femal and male contacts
(Order-no.: C.1303.01)
Shield
CAN cable
Order-no.: C.1323.03
CAN cable
Order-no.: C.1323.03
CAN cable
Order-no.: C.1323.03
Termination connector
"CAN-Termination-DSUB"
Order-no.: C.1303.01
