Rockwell Automation Allen-Bradley 1769-ASCII, User Manual

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44 Rockwell Automation Publication 1769-UM012B-EN-P - January 2014
Chapter 2 Configure the 1769-ASCII Module
Input Channel1
The Input Channel1 does the following tasks:
•
On first scan, store current value of Rx1 Transaction ID (channel 1) as
‘most recent’
•
When the Rx Transaction ID changes, it indicates there is ‘new data.’
•
Copies data from the module's Input Tags to a STRING tag
(InData1) if CNI = 1.
•
Indicates to the MainRoutine that new data has arrived. Saves this value of
Rx Transaction ID, so you can detect the next change.