National Instruments AT-MIO E Series, Programmer'S Manual, Page: 25 / 169

Chapter 2 Theory of Operation
© National Instruments Corporation 2-13 AT-MIO E Series RLPM
The SC is a 24-bit counter that counts the number of scans. The data
acquisition sequence can be programmed to stop when the terminal count
of this counter is reached. Notice that the START and STOP signals could
also be supplied externally.
Example 1: To acquire 50 scans, with each scan consisting of one sample
on channel 0 at gain 50, one sample on channel 5 at gain 2, and one sample
on channel 3 at gain 10, with a SCAN interval of 100
µ
s and a sample
interval of 10
µ
s, program your configuration memory as follows:
1. channel 0, gain 50
2. channel 5, gain 2
3. channel 3, gain 10, last channel
You should program SI2 for 10
µ
s, SI for 100
µ
s, and SC for 50 (50 scans).
Figure 2-9 shows the timing for each scan in Example 1.
Figure 2-9. Timing of Scan in Example 1
The START pulse starts each scan. The first CONVERT pulse samples
channel 0, the second CONVERT pulse samples channel 5, and the third
CONVERT pulse samples channel 3. The STOP pulse ends the scan.
Example 1 allows you to sample all three channels at a rate of 10 kS/s per
channel (100
µ
s sample interval period). To achieve different rates for
different channels, you must do multirate scanning.
100
µ
s
10
µ
s
Channel 0 Channel 5 Channel 3
START
(TC of SI)
STOP
(last channel
or DIV TC)
CONVERT