Condition
Prescan
Rung-condition-in is false
Rung-condition-in is true
Evaluate Limit
Rung-condition-out is set
Postscan
Condition
Prescan
Instruction first scan
Instruction first run
EnableIn is cleared
EnableIn is set
Postscan
Execution:
Relay Ladder
Action
The rung-condition-out is set to false.
The rung-condition-out is set to false.
Comparison is true.
Comparison is false.
to false.
The rung-condition-out is set to false.
Function Block
Action
No action taken.
No action taken.
No action taken.
EnableOut is cleared, the instruction does nothing, and the outputs are not updated.
The instruction executes.
EnableOut is set.
No action taken.
Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
Compare Instructions (CMP, EQU, GEQ, GRT, LEQ, LES, LIM, MEQ, NEQ)
Rung-condition-out is set
to true.
End
Chapter 5
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