National Instruments PXI-846x Series 用户手册
Appendix B
Cabling Requirements for PXI-8460 Low-Speed CAN
© National Instruments Corporation
B-3
Connecting pins 2 and 3 of a jumper configures the CAN physical layer to
be powered internally (from the card). In this configuration, the V– signal
serves as the reference ground for the isolated signals. Even if the CAN
physical layer is powered internally, the fault-tolerant CAN transceiver still
requires bus power to be supplied in order for it to monitor the power supply
(battery) voltage.
be powered internally (from the card). In this configuration, the V– signal
serves as the reference ground for the isolated signals. Even if the CAN
physical layer is powered internally, the fault-tolerant CAN transceiver still
requires bus power to be supplied in order for it to monitor the power supply
(battery) voltage.
Figure B-3 shows how to configure your jumpers for internal or external
power supplies.
power supplies.
Figure B-3. Power Source Jumpers
The CAN physical layer is still isolated regardless of the power source
chosen.
chosen.
Bus Power Supply Requirements
If the CAN physical layer is powered from a bus power supply, the power
supply should be a DC power supply with an output of 8 V to 27 V. The
power requirements for the CAN ports for Bus-Powered configurations are
shown in Table B-1. You should take these requirements into account when
determining requirements of the bus power supply for the system.
supply should be a DC power supply with an output of 8 V to 27 V. The
power requirements for the CAN ports for Bus-Powered configurations are
shown in Table B-1. You should take these requirements into account when
determining requirements of the bus power supply for the system.
Table B-1. Power Requirements for the Low-Speed CAN Physical Layer
for Bus-Powered Versions
Characteristic
Specification
Voltage requirement
V+ 8–27 VDC
Current requirement
40 mA typical
100 mA maximum
100 mA maximum
INT
EXT
a. Internal Power Mode
INT
EXT
b. External Power Mode
1
2
3
1
2
3