NI sbRIO-960x/962x/963x OEM Instructions & Specifications 40 ni.com
Figure 31 shows a simplified diagram of a CAN bus with multiple CAN
nodes and proper termination resistor (Rt) locations.
Figure 31. CAN Bus Topology and Termination Resistor Locations
Cable Specifications
Cables should meet the physical medium requirements specified
in ISO 11898, shown in Table 9. Belden cable (3084A) meets all these
requirements and is suitable for most applications.
Termination Resistors
The termination resistors (R
t
) should match the nominal impedance of the
CAN cable and therefore comply with the values in Table 10.
.
Table 9. ISO 11898 Specifications for Characteristics of a CAN_H and CAN_L Pair of Wires
Characteristic Value
Impedance 95 Ω minimum, 120 Ω nominal, 140 Ω maximum
Length-related resistance 70 mΩ/m nominal
Specific line delay 5 ns/m nominal
Table 10. Termination Resistor Specification
Characteristic Val ue Condition
Termination resistor, R
t
100 Ω min,
120 Ω nominal,
130 Ω max
Minimum power dissipation: 220 mW
CAN
Node
CAN
Node
CAN
Node
R
t
R
t
CAN
Node
CAN_H
CAN_L
CAN_H
CAN_L
CAN_H
CAN_L
CAN_H
CAN_L
Bus Cable Length
Stub
Length
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