
Chapter 5
Programming
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National Instruments Corporation
5-13
to use TRIG0 as their clock source. For SCXI-1121 modules, this
programming is accomplished by writing the binary pattern
01S
c
XXXCC XX001111
to their Configuration Registers.
Multiple-Chassis Scanning
To scan modules on multiple chassis, you must use the SCXI-1001. The
cable from the data acquisition board must bus the digital lines to one
module on each chassis. Additionally, the cable must provide each chassis
with its own analog channel. The data acquisition board must be able to
take several readings at a time on a given channel before accessing a new
channel. Refer to the
subsection of the
Acquisition Board Setup Programming
section earlier in this chapter.
You can use the MIO-16 boards in conjunction with the SCXI-1350
multichassis adapter for multichassis scanning.
For each chassis, program the modules according to the appropriate mode
of operation, disregarding the fact that other chassis will be involved.
For example, you want to scan thirteen modules. Twelve modules are in
one chassis. The thirteenth is in the second chassis and is to be scanned
through a fourteenth module that is cabled to the data acquisition board but
is not involved in the scan. Program the twelve modules in the first chassis
according to the steps in the previous
section, and program the thirteenth and fourteenth modules
Channel Scanning from the SCXI-1121 via Another Module
earlier in this chapter.
3. Programming the Slot 0 Hardscan Circuitry
The following section describes how to program the Slot 0 circuitry for
scanning operations. For a more detailed description of the Slot 0 scanning
circuitry, consult the
SCXI Chassis User Manual
. Descriptions of the Slot
0 registers are given in the section
in
. Skip this section if you are doing
single-module parallel scanning.
To program the hardscan circuitry, perform the following steps:
1.
Write binary
0000 0000
to the HSCR.
2.
Write binary
0000 1000
to the HSCR.
3.
Write the Slot 0 scan list to the FIFO.
4.
Write binary
0010 1100
to the HSCR.
5.
Write binary
101S 1100
to the HSCR.