Chapter 5 Programming
SCXI-1121 User Manual 5-10 www.natinst.com
To program the MIO board to take N samples per data acquisition board
scan list entry, perform the following additional programming steps at the
end of the Enable the Scanning Data Acquisition Operation section in the
appropriate data acquisition board user manual:
1. Write FF01 to the Am9513 Command Register to select Counter 1
Mode Register.
2. Write 0325 (hex) to the Am9513 Data Register to store Counter 1
Mode Value for most MIO boards. Write 1325 (hex) to the Am9513
Data Register to store Counter 1 Mode Value for the AT-MIO-16F-5,
AT-MIO-64F-5, and AT-MIO-16X boards.
3. Write FF09 to the Am9513 Command Register to select Counter 1
Load Register.
4. Write the number of samples to be taken per scan list entry (2 to
65,535) to the Am9513 Data Register to load Counter 1.
5. Write FF41 to the Am9513 Command Register to load Counter 1.
6. Write FFF1 to the Am9513 Command Register to step Counter 1.
7. Write FF21 to the Am9513 Command Register to arm Counter 1.
8. Set the SCANDIV bit in Command Register 1.
2. Module Programming
This section describes the programming steps for various scanning
possibilities. For all the bit patterns in this section, Sc signifies the shunt
calibration bit. If you set this bit to one, the module will be scanned in Shunt
Calibration mode. If you clear this bit to zero, shunt calibration will be
disabled on the module during scanning. When programming a module to
change the shunt calibration mode from disabled to enabled or vice versa,
insert a delay before you make any measurements. If the SCXI-1121 has a
filter setting at 10 kHz, the delay should be at least 1 msec. If the
SCXI-1121 has the filter set at 4 Hz, the delay should be at least 1 sec.

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. See
Chapter2, 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.