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

Description:
Arithmetic Status Flags:
Fault Conditions:
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
The Source must be greater than zero, otherwise the overflow status bit (S:V) is
set. The resulting Destination is greater than or equal to -87.33655 and
less than or equal to 88.72284.
Arithmetic status flags are affected.
None
Execution:

Relay Ladder

Action
The rung-condition-out is set to false.
The rung-condition-out is set to false.
The controller calculates the natural log of the Source 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
Advanced Math Instructions (LN, LOG, XPY) Chapter 15
547