Allen-Bradley LOGIX 5000 Reference Manual page 60

Chapter 1 Process Control Instructions
60
Before calculating Out, the X axis parameters are scanned. If they are not sorted in
ascending order, the appropriate bit in Status is set and Out remains unchanged.
Also, if XY1Size or XY2Size is invalid, the instruction sets the appropriate bit in
Status and leaves Out unchanged.
The instruction uses this algorithm to calculate Out based on In:
•
When In X[1], set Out = Y[1]
•
When In > X[XY<n>Size], set Out = Y[XY<n>Size]
•
When X[n] < In
Xn))*(In-Xn)+Yn
Affects Math Status Flags
No
Major/Minor Fault
None specific to this instruction. See Common Attributes for operand-related
faults.
Execution
Function Block
Condition
Prescan
Tag.EnableIn is false
Tag.EnableIn is true
Instruction first run
Instruction first scan
Postscan
Structured Text
Condition/State
Prescan
Normal Execution
Postscan
Rockwell Automation Publication 1756-RM006K-EN-P - November 2018
X[n+1], calculate Out = ((Y[n+1]-Yn)/ (X[n+1]-
Function Block Action
EnableIn and EnableOut bits are cleared to false.
EnableIn and EnableOut bits are cleared to false.
EnableIn and EnableOut bits are set to true. The instruction executes.
N/A
N/A
EnableIn and EnableOut bits are set to true. The instruction executes.
Action Taken
See Prescan in the Function Block table.
See Tag.EnableIn is true in the Function Block table.
See Postscan in the Function Block table.