STW TC1, User Manual

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10 Application Notes
User Manual 320/374
10.1.7 CAN
CAN-Termination
According to the CAN specification, every end of a CAN bus trunk-line must be terminated with a 120 Ohm
Resistor.
Example of a terminated CAN bus:
CAN-Bus length (Trunk-line length)
The CAN bus length (Trunk-line length) is limited and depends on the Baud-rate, the CAN bus is operated with.
The following table shall give an overview of maximum CAN bus length according to the used Baud rate.
Baud-Rate [kbit/s] CAN-bus length
1000 (1MBit/s) < 20m
500 < 100
250 < 250
125 < 500
50 < 1000
20 < 2500
10 < 5000
Drop-line length
Drop-lines are allowed, but should be avoided, as they typically create signal echo. Drop-lines must not be
terminated with 120 Ohm resistors! The following table shows the maximum lengths of drop-lines to be used:
Baud-Rate
[kBit/s] Drop-line length
[m] Total length of all drop-lines
[m]
1000 (1Mb/s) < 1 < 5
500 < 5 < 25
250 < 10 < 50