Relay Ladder; Function Block - Allen-Bradley Logix5000 Reference Manual

Chapter 15 Advanced Math Instructions (LN, LOG, XPY)
Condition
Prescan
Rung-condition-in is false
Rung-condition-in is true
Postscan
Condition
Prescan
Instruction first scan
Instruction first run
EnableIn is cleared
EnableIn is set
Postscan
554
Execution:

Relay Ladder

Action
The rung-condition-out is set to false.
The rung-condition-out is set to false.
The controller takes Source X to the power of Source Y and places the result in the Destination.
The rung-condition-out is set to true.
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 executes.
EnableOut is set.
No action taken.
Rockwell Automation Publication 1756-RM003N-EN-P - October 2011