Chapter 9 Communication instructions
220 Rockwell Automation Publication 2080-RM001D-EN-E - February 2015
Message execution timing diagram (Rung = FALSE)
The following table describes the message conditions and bit status for each
execution step identified in the timing diagram when the rung goes to FALSE
during execution.
Step Message description Bit status
1
Rung condition goes TRUE.
Message executioy is enabled.
EN bit is set.
All other bits are cleared.
2
Rung condition goes FALSE.
Message execution continues.
3
Message buffer is acquired.At this time, input data (that is, the "data"
parameter for write messages) is copied for transmission. Subsequent
changes to the input data will not be reflected in the transmitted message.
EW bit is set.
4
Message transmission starts. EW bit is cleared.
ST bit is set.
5
Message response is received. ST bit is cleared.
DN bit is set.
6
Message is scanned again after step 5. EN bit is cleared.
Timing diagram for (Rung = FALSE)
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