Figure 2-10. Multirate Scanning Of Two Channels; Figure 2-11. Multirate Scanning Of Two Channels With 1:X Sampling Rate - National Instruments PCI E Series Programmer's Manual

Sampling Rate
Channel 0: Channel 1 = 2:1
START
CONVERT
STOP
Sampling Rates
Channel 0: Channel 1 = 5:1
START
CONVERT
STOP
© National Instruments Corporation
Program SI for 100 µs, SI2 for 10 µs. Figure 2-10 shows the timing
sequence for two scans.
Channel 0

Figure 2-10. Multirate Scanning of Two Channels

This sequence of two scans is repeated 25 times to complete the acquisition.
Notice that channel 0 is sampled once every 100 µs. Hence, its sampling
rate is 10 kS/s, whereas channel 1 is sampled once every 200 µs. Its rate is
5 kS/s. Similarly, you could implement any 1:x ratio of sampling rates. The
effective scan interval of the slower channel will be at
faster channel. This implementation requires x scan sequences in the
configuration memory.
Also, you can implement a 1:1:x or 1:x:mx ratio for three channels, where
m is a non-negative integer. Figures 2-11, 2-12, and 2-13 show timing
sequences for different ratios. In these figures, the numbers above the
CONVERT pulses indicate the channels sampled in that conversion.
0 0
1
0
Figure 2-11. Multirate Scanning of Two Channels with 1: x Sampling Rate
Channel 1 Channel 0
0 0
2-15
Chapter 2 Theory of Operation
1
the rate of the
x -- -
0
PCI E Series RLPM