CAN Bus Topology and Termination
A CAN bus consists of two or more CAN nodes cabled together.
The CAN_H and CAN_L pins of each node are connected to the
main CAN bus cable through a short connection known as a
“stub.” The pair of signal wires, CAN_H and CAN_L, constitutes
a transmission line. If the transmission line is not terminated,
each signal change on the bus causes reflections that may cause
communication errors. Because the CAN bus is bidirectional,
both ends of the cable must be terminated. However, this
requirement does not mean that every node on the bus should
have a termination resistor; only the two nodes at the far end of
the cable should have termination resistors.
Figure 1 shows a simplified diagram of a CAN bus with multiple
CAN nodes and proper termination resistor (R
t
) locations.
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NI 9862 Getting Started Guide
