Chapter 5 Programming
© National Instruments Corporation 5-5 SCXI-1120 User Manual
To measure one of the eight differential input channels to the SCXI-1120, perform the following
steps:
1. Perform any necessary programming to ensure that no modules are driving Analog Bus 0.
For an SCXI-1120, 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 00XXXCCC XX000010 to the SCXI-1120 Configuration Register.
4. 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-1120, 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 00XXXXXX XX100010 to the SCXI-1120 Configuration Register.
4. Measure the voltage with the data acquisition board.
Scanning Measurements
Programming for scanned data acquisition involves programming your data acquisition board,
modules, and Slot 0. In general, the steps to be taken are as follows:
1. Perform all data acquisition board programming to the point of enabling the data
acquisition.
2. Perform all module programming.
3. Program the Slot 0 hardscan circuitry.
4. Enable the data acquisition, trigger it either through software or hardware, and service the
data acquisition.
The MIO boards can do all types of scanning. Lab-NB, Lab-PC, Lab-PC+, Lab-LC, and
PC-LPM-16 boards support only single-module parallel scanning, and do not support any of the
multiplexed scanning modes. Notice that single-module parallel scanning is typically done
without any module or Slot 0 programming; only programming the data acquisition board is
necessary.