ADLINK cPCI-9116 - Manual (Page 46)

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• Operation Theory
5.1.2.1 Specifying Channels, Gains, and input configurations in the
Channel Gain Queue
In both Software Polling and programmable scan acquisition mode, the
channel, gain, and input configuration (single-end, differential, and U_CMMD),
where you want to acquire samples from, can be specified in the Channel
Gain Queue. You can set the channel number in the Channel Gain Queue in
any order. Therefore, you can control the channel order from which data is
acquired with different gain and input configuration for each channel. The
maximum number of entries you can set is 512 channels. The channel order of
acquisition is the same as the order you set in the Channel Gain Queue. When
the specified channels are sampled from the beginning to the end in the
Channel Gain Queue, the channels in the Channel Gain Queue will be
sampled again until the specified number of samples has been acquired.
5.1.3 Programmable scan acquisition mode
5.1.3.1 Scan Timing and Procedure
It's recommended that this mode be used, if your application needs a fixed and
precise A/D sampling rate. You can accurately program the period between
conversions of each individual channel in the scan and the period between
conversions of the entire scan. There are 4 counters, which need to be
specified:
SI_counter(24 bit): Specify the Scan Interval = SI_counter / Timebase
SI2_counter(16 bit): Specify the data Sampling Interval =
SI2_counter/Timebase
SC_counter(24 bit): Specify Scan Count Counter after trigger
DIV_counter(9 bit): Specify the number of samples per scan
The acquisition timing and the meaning of the 4 counters are illustrated in
figure 9.