Allen-Bradley Logix5000 Reference Manual page 161

Where Description
1 Rung-condition-in is true.
.EN is set.
.EW is set.
Connection is opened*.
2 Message is sent.
.ST is set.
.EW is cleared.
3 Message is done or errored.
Rung-condition-in is false.
.DN or .ER is set.
.ST is cleared.
Connection is closed (if .EN_CC = 0).
.EN is cleared (rung-condition-in is false).
4 Rung-condition-in is true.
.DN or .ER was previously set.
.EN is set.
.EW is setCconnection is opened*.
.DN or .ER is cleared.
Condition
Prescan
Execution:
Relay Ladder Action
The rung-condition-out is set to false.
Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
Input/Output Instructions (MSG, GSV, SSV, IOT)
Where Description
5 Message is sent.
.ST is set.
.EW is cleared.
6 Message is done or errored.
Rung-condition-in is still true.
.DN or .ER is set.
.ST is cleared.
Connection is closed (if .EN_CC = 0).
7 Rung-condition-in goes false and .DN or .ER is set.
.EN is cleared.
N/A N/A
Structured Text Action
No action taken.
Chapter 4
161