Chapter 5 Programming
SCXI-1121 User Manual 5-6 www.natinst.com
Measurements from the SCXI-1121 via Another Module
To perform measurements via another module, you must cable the other
module rear signal connector to a data acquisition board. The other module
must also be able to transfer Analog Bus 0 to the data acquisition board. See
Chapter2, Configuration and Installation, for more information.
To measure one of the four differential input channels to the SCXI-1121,
perform the following steps:
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. Program the other module not to drive Analog Bus 0, but to send
Analog Bus 0 to the data acquisition board.
3. Write the binary pattern 000XXXCC XX000010 to the SCXI-1121
Configuration Register.
4. Measure the voltage with the data acquisition board.
To perform a shunt calibration on one of the four differential input channels
of the SCXI-1121, perform the following steps:
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. Program the other module not to drive Analog Bus 0, but to send
Analog Bus 0 to the data acquisition board.
3. Write the binary pattern 001XXXCC XX000010 to the SCXI-1121
Configuration Register.
4. Insert a delay equal to 1 sec if you have set the 4 Hz filter, or 1 msec if
you have set the 10 kHz filter. This delay permits the SCXI-1121
amplifier to settle.
5. Measure the voltage with the data acquisition board.
To measure the voltage on the MTEMP line, perform the following steps:
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. Program the other module not to drive Analog Bus 0, but to send
Analog Bus 0 to the data acquisition board.
3. Write the binary pattern 000XXXXX XX100010 to the SCXI-1121
Configuration Register.
4. Measure the voltage with the data acquisition board.