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Appendix B Cabling Requirements for PXI-8460 Low-Speed CAN
PXI-846x and NI-CAN for Windows NT B-6 ni.com
Philips also recommends an individual device RTH and RTL termination of
500 Ω to 16 kΩ. The PXI-8460 board ships with mounted RTH and RTL
values of 510 Ω ±5% per port. The PXI-8460 kit also includes a pair of
15 kΩ ±5% resistors for each port. After determining the termination of
your existing network or device, you can use the following formula to
indicate which value should be placed on your PXI-8460 board in order to
produce the proper overall RTH and RTL termination of 100 to 500 Ω upon
connection of the board:
*R
RTH overall
should be between 100 and 500 Ω
**R
RTH oflow-speed CANinterface
=510Ω ±5% (mounted) or 15 kΩ ±5% (in kit)
†R
RTH
= R
RTL
As the formula indicates, the 510 Ω ±5% shipped on your board will work
with properly terminated networkshaving atotal RTH and RTL termination
of 125 to 500 Ω, or individual devices having an RTH and RTL termination
of 500 Ω to 16 kΩ. For communication with a network having an overall
RTH and RTL termination of 100 to 125 Ω, you will need to replace the
510 Ω resistors with the 15 kΩ resistors in the kit. Please refer to the next
section, Replacing the Termination Resistors.
R
RTH overall*
†
1
1
R
RTH of low-speed CAN interface**
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1
R
RTH of existing network or device
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