Counter 1 and scandiv – National Instruments SCXI-1121 User Manual
Page 100
Chapter 5
Programming
© National Instruments Corporation
5-9
Follow the instructions in these sections through the part labeled as follows:
•
Clear the A/D Circuitry and Reset the Mux Counter in the MIO board
user manual (except for the AT-MIO-16X and the AT-MIO-64F-5). Do
not continue to the part called Enable the Scanning Data Acquisition
Operation. You will do this after you program the modules and Slot 0.
•
Program the Sample Counter (if you are doing continuous channel
scanning) or Program the Scan-Interval Counter (if you are doing
interval channel scanning) in the AT-MIO-16X or AT-MIO-64F-5 user
manual. Do not continue to the part labeled Enable a Scanning Data
Acquisition Operation or Enable an Interval Scanning Data
Acquisition Operation. You will do this after you program the modules
and Slot 0.
Note
For multiplexed scanning with an MIO board, it is important that you follow the
instructions in the channel-scanning sections, not the single-channel sections. Although
you may be using only one MIO board channel, the channel scanning programming will
ensure that the MIO board outputs SCANCLK, which is needed by the SCXI-1120 and
Slot 0.
•
Clear the A/D Circuitry in the Lab-LC User Manual. Do not continue
to the part called Program the Sample-Interval Counter. You will do
this after you program the modules and Slot 0.
•
Clear the A/D Circuitry in the Lab-PC User Manual, the Lab-PC+
User Manual, and the PC-LPM-16 User Manual. Do not continue to
the part called Start and Service the Data Acquisition Operation. You
will do this after you program the modules and Slot 0.
•
Clear the A/D Circuitry in the Lab-NB User Manual. Do not continue
to the part called Program the Sample-Interval Counter (Counter A0).
You will do this after you program the modules and Slot 0.
Counter 1 and SCANDIV
All MIO boards can operate their data acquisition board scan lists in two
ways—they can acquire one sample per data acquisition board scan list
entry or they can acquire N samples per data acquisition board scan list
entry, where N is a number from 2 to 65,535 that is programmed in
Counter 1. This second method of operation is especially useful when the
data acquisition board scan list length is limited to 16 entries, as it is on all
MIO boards except the AT-MIO-16F-5, which can have up to 512 entries.
Because you can multiplex many SCXI-1121s in one chassis to one MIO
board channel, often the simplest way to program the MIO board is to use
only one data acquisition board scan list entry, and make N the total number
of samples to be taken on all modules in one scan. Check your MIO board
user manual for limitations in the data acquisition board scan list format.