Chapter 5 Programming
SCXI-1121 User Manual 5-4 www.natinst.com
to MCH0 through MCH3 on the rear signal connector. The module is
disconnected from Analog Bus 0 and disabled from scanning.
Single-Channel Measurements
This section describes how to program the SCXI-1121, either alone or in
conjunction with other modules, to make single-channel, or nonscanned,
measurements.
Direct Measurements

Parallel Output

In order to perform a parallel output measurement, 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. See
Chapter2, Configuration and Installation, for more information. For
information on how to make the voltage measurement with your data
acquisition board, consult your data acquisition board user manual.
Remember to account for the gains of both the SCXI-1121 and the data
acquisition board when calculating the actual voltage present at the input of
the SCXI-1121.
To measure one of the four differential input channels to the SCXI-1121, or
the DTEMP line if the module has been configured appropriately, perform
the following steps:
1. Write the binary pattern 000XXX00 XX000000 to the SCXI-1121
Configuration Register. Notice that this can be the RESET state.
2. Measure the voltage with the data acquisition board.

Multiplexed Output

In order to perform a direct multiplexed output measurement, you must
cable the SCXI-1121 rear signal connector to a data acquisition board.
See Chapter 2, Configuration and Installation, for more information. For
information on how to make the voltage measurement with your data
acquisition board, consult your data acquisition board user manual.
Remember to account for the gains of both the SCXI-1121 and the data
acquisition board when calculating the actual voltage present at the input
ofthe SCXI-1 121.