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Chapter 5
Programming
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National Instruments Corporation
5-11
Single-Module Parallel Scanning
In order to perform single-module parallel scanning, you must cable the
SCXI-1121 rear signal connector to a data acquisition board with each
output connected to a different data acquisition board channel. Refer to
Chapter 2,
Configuration and Installation
, for more information.
To program the SCXI-1121 for single-module parallel scanning, write the
binary pattern
00ScXXX00 XX000000
to the SCXI-1121 Configuration
Register. Notice that this can be the RESET state.
Single-Module Multiplexed Scanning (Direct)
To perform simple channel scanning, you must cable the SCXI-1121 to a
data acquisition board. Refer to Chapter 2,
Configuration and Installation
for more information.
To program the module for scanned channel measurements, write the
binary pattern
10ScXXXCC XX001101
to the SCXI-1121 Configuration
Register. CC represents the starting channel number.
Single-Module Multiplexed Scanning (Indirect)
To indirectly scan a module, send the output of the scanned module onto
Analog Bus 0, where it will be picked up by another module and
transmitted to the data acquisition board.
Channel Scanning from Other Modules
To scan measurements from other modules, you must cable the SCXI-1121
to a data acquisition board. Refer to Chapter 2,
, for more information. The module programming steps are as
follows:
1.
Perform any necessary programming to ensure that no modules are
driving Analog Bus 0. For an SCXI-1121, clearing AB0EN in the
Configuration Register will ensure that its output is not driving AB0.
2.
Write the binary pattern
10XXXXXX XX100011
to the SCXI-1121
Configuration Register. This step disables the SCXI-1121 from driving
Analog Bus 0 and allows Analog Bus 0 to drive MCH0 through the
output buffer.
3.
Program the other module to be scanned.