Configuration and Installation
Chapter 2
SCXI-1162 User Manual
2-6
© National Instruments Corporation
acquisition board can read the Module ID Register or the Data Register of the SCXI-1162. See
the Timing Requirements and Communication Protocol section later in this chapter, and Chapter
4, Register Descriptions, for information on reading the Module ID Register and the Data
Register. See Appendix E, SCXI-1162 Cabling, for the pin equivalences of the SCXI-1162 rear
signal connector and the data acquisition board I/O connector. The factory-default setting is
position DIO.
Position PAR disconnects SERDATOUT from the SCXIbus MISO line, and you should use it
when the module is to be connected in parallel to a DIO board.
Using Jumpers W5 and W6
If a module is not connected to a data acquisition board, the positions of W5 and W6 are
irrelevant. Jumpers W5 and W6 give the data acquisition board access to the MISO line on the
backplane. You use the MISO line to read the values at the module inputs from the Data
Register and to read the Module ID Register of modules. National Instruments software does not
use the ability to read the Module ID register. You must indicate to the software which module
is in which slot.
The SERDATOUT line is driven with an open-collector driver, which is a driver that actively
drives low or goes to a high-impedance state, relying on a pullup resistor to make the signal line
go high. When you use a single chassis, set W5 in position A on the SCXI-1162 that is
connected to the data acquisition board and set W6 to DIO or MIO. In this setting, the module
drives MISO to SERDATOUT and connects the necessary pullup resistor to the SERDATOUT
line. When using multiple chassis, set jumper W6 to position DIO or MIO on all of the
SCXI-1162s that are cabled to the data acquisition board. Only one of the SCXI-1162s that are
cabled to the data acquisition board should have jumper W5 in position A. It does not matter
which of the SCXI-1162s that are cabled to the data acquisition board has the pullup connected.
All of the other SCXI-1162 modules that are cabled to the data acquisition board should have
jumper W5 in position B. If too many pullup resistors are attached to the SERDATOUT line, the
drivers cannot drive the line low.
