©
National Instruments Corp.
13
NI 9853 Operating Instructions
Termination Resistors
The termination resistors (R
t
) should match the nominal
impedance of the CAN cable, and therefore comply with the values
in Table 4.
Cable Lengths
The allowable cable length is affected by the characteristics of the
cabling and the desired bit transmission rates. Detailed cable length
recommendations can be found in the ISO 11898, CiA DS 102, and
DeviceNet specifications.
ISO 11898 specifies 40 m total cable length with a maximum
stub length of 0.3 m for a bit rate of 1 Mb/s. The ISO 11898
specification says that significantly longer cable lengths may be
allowed at lower bit rates, but each node should be analyzed for
signal integrity problems.
Table 4.
Termination Resistor Specification
Characteristic
Value
Condition
Termination resistor, R
t
100
Ω
min,
120
Ω
nominal,
130
Ω
max
Minimum power
dissipation: 220 mW
