Advantech PCI-1713 User Manual page 30

Example 1 If the start scan input channel is AI3 and the stop scan
input channel is AI7, then the scan sequence is AI3, AI4, AI5, AI6, AI7,
AI3, AI4, AI5, AI6, AI7, AI3, A I 4 ...
Example 2 If the start scan channel is AI29 and the stop scan
channel is AI2, then the scan sequence is AI29, AI30, AI31, AI0, AI1,
AI2, AI29, AI30, AI31, AI0, AI1, AI2, AI29, AI30...
This scan logic of the PCI-1713 card is quite powerful and easily
understood. You can respectively set the gain code, B/U and S/D, for
each channel. The scan logic will be a little complex if you set the
analog input channels in differential mode, however. In differential
mode, signals are transmitted by a pair of channels, AI<i, i+1> ( i = 0,
2, 4,..., 30) . In each pair of differential channels, the even channel is
the positive end and the odd one is the negative end.
For example, if channel 0 is set as differential, then channel 0 and
channel 1 are combined into one channel and refer to the gain code
and B/U of channel 0 (the channel 1 values are unavailable). By the
same rule, if channel 2 is set as differential, then channel 2 and channel
3 are combined into one channel, and refer to the gain code and B/U of
channel 2 (the channel 3 values are unavailable). The following
examples show the scan sequences in differential mode.
Example 3 Suppose that the start scan input channel is AI30 and the
stop scan input channel is AI3. If AI30 is differential, AI0 and AI1 are
single-ended, and AI2 is differential, then the scan sequence is AI30,
AI0, AI1, AI2, AI30, AI0, AI1, AI2, AI30.....
Example 4 Suppose that the start scan channel is AI27 and the stop
scan channel is AI131. If AI27 is single-ended, AI28 is differential,
and AI30 is differential, then the scan sequence is AI27, AI28, AI30,
AI27, AI28, AI30, AI27...
Warning! Only even channels can be set as differential. An
2 6 PCI-1713
odd channel will become unavailable if its preceding
channel is set as differential.
User's Manual