222 Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
Chapter 5 Compare Instructions (CMP, EQU, GEQ, GRT, LEQ, LES, LIM, MEQ, NEQ)
Execution:
Examples: If the CMP instruction finds the expression true, the rung-condition-out is set to
true.
If you enter an expression without a comparison operator, such as
value_1 + value_2, or value_1, the instruction evaluates the expression
as explained in the table.
Condition Relay Ladder 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.
End
Evaluate Expression
Expression is true.
Expression is false.
Rung-condition-out is set
to true.
Rung-condition-out is set
to false.
Rung-condition-in is true
If the expression is The rung-condition-out is set to
Non-zero True
Zero False
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