Allen-Bradley Logix5000 Reference Manual page 222

Chapter 5 Compare Instructions (CMP, EQU, GEQ, GRT, LEQ, LES, LIM, MEQ, NEQ)
Condition
Prescan
Rung-condition-in is false
Rung-condition-in is true
Postscan
222
Execution:
Relay Ladder Action
The rung-condition-out is set to false.
The rung-condition-out is set to false.
Evaluate Expression
Expression is false.
Rung-condition-out is set
to false.
The rung-condition-out is set to false.
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.
If the expression is
Non-zero
Zero
Rockwell Automation Publication 1756-RM003N-EN-P - October 2011
Expression is true.
Rung-condition-out is set
End
The rung-condition-out is set to
True
False
to true.