GE IC697ALG230 Input Sampling Techniques
Input Sampling Techniques
The objective of the input sampling technique for the
analog subsystem is to provide 8 input channels on
the base module that have a fast (approximately 3 ms)
update rate and additional expander channels that are
updated less frequently, but have a lower cost per
channel.
Operation is such that the base module initially up
dates all eight channels plus one expander channel.
On each successive scan all eight channels of the base
converter are again updated – plus the next expander
channel in sequence. After 16 analog input scans all 16
channels of the first expander have been sampled; on
the next scan, all eight base converter channels plus
the first channel of the next Expander module are
scanned.
This sampling technique continues until all available
expander channels (16 x number of Expander mod
ules) have been scanned, at which time the sequence
starts over. The number of analog scans required to
include sampling of all expander channels is equal to
the total number of Expander modules x 16 (16 chan
nels per Expander module) in the system.