Chapter 5
Programming
© National Instruments Corporation
5-3
SCXI-1100 User Manual
7. Pull SLOT0SEL* low to deassert the SS* line, latch the data into the Configuration Register,
and establish conditions for writing a new slot-select number to the Slot 0 Slot-Select
Register.
8. If you are not selecting another slot, write zero to the Slot 0 Slot-Select Register. If you are
selecting another slot, repeat this procedure starting at step 3.
For a timing illustration of a Configuration Register write, see Figure 2-12, Configuration
Register Write Timing Diagram, which shows the proper write to configure an SCXI-1100 that is
directly cabled to an MIO board for multiple-module multiplexed scanning with a start channel
of 31 and an amplifier gain of 2,000.
Initialization
The SCXI-1100 powers up with its Configuration Register cleared to all zeros. You can force
this state by pressing the Reset button on the front panel of Slot 0. In the reset state, the module
outputs CH0 to MCH0
±
of the rear signal connector and can be clocked via SCANCLK to
subsequent channels. The module is disconnected from Analog Bus 0. The total amplifier gain
is 1.
Single-Channel Measurements
This section describes how to program the SCXI-1100, either alone or in conjunction with other
modules, to make single-channel, or nonscanned, measurements.
Direct Measurements
To perform a direct measurement, you must cable the SCXI-1100 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-1100 and the data acquisition board when calculating the actual voltage present at the
input of the SCXI-1100.
To measure one of the 32 differential input channels to the SCXI-1100, perform the following
steps:
1. Write the binary pattern
XXXGGGGG 00XCCCCC 00001000
to the SCXI-1100
Configuration Register.
2. Measure the voltage with the data acquisition board.
To measure the voltage on the MTEMP line, perform the following steps:
1. Write the binary pattern
XXX00000 00XXXXXX 00101000
to the SCXI-1100
Configuration Register.
2. Measure the voltage with the data acquisition board.