228 Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
Chapter 5 Compare Instructions (CMP, EQU, GEQ, GRT, LEQ, LES, LIM, MEQ, NEQ)
Relay Ladder
Function Block
Condition Action
Prescan The rung-condition-out is set to false.
Rung-condition-in is false The rung-condition-out is set to false.
Postscan The rung-condition-out is set to false.
Rung-condition-in is true
End
Source A = Source B
Yes
No
Rung-condition-out is set
to true.
Rung-condition-out is set
to false.
Condition Action
Prescan No action taken.
Instruction first scan No action taken.
Instruction first run No action taken.
EnableIn is cleared EnableOut is cleared.
EnableIn is set The instruction executes.
EnableOut is set.
Postscan No action taken.