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

Chapter 6 Compute/Math Instructions (CPT, ADD, SUB, MUL, DIV, MOD, SQR, SQRT, NEG, ABS)
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
284
If the Destination is not a REAL, the instruction handles the fractional portion
of the result as follows:
If the source is
Not a REAL
A REAL
If the Source is negative, the instruction takes the absolute value of the Source
before calculating the square root.
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.
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
Then the fractional
portion of the result
Truncates
Rounds
= Source
Example
Source DINT 3
Destination DINT 1
Source REAL 3.0
Destination DINT 2