Allen-Bradley LOGIX 5000 Reference Manual page 55

Process Control Instructions
Execution
Function Block
Condition/State
Prescan
Tag.EnableIn is false
Tag.EnableIn is true
Instruction first run
Instruction first scan
Postscan
Structured Text
Condition/State
Prescan
Normal Execution
Postscan
Example
In this example, the DEDT instruction simulates a deadtime delay in a simulated
process. The output of the PIDE instruction is passed through a deadtime delay
and a first-order lag to simulate the process. The array DEDT_01array is a REAL
array with 100 elements to support a deadtime of up to 100 samples. For example,
if this routine executes every 100 msec, the array would support a deadtime of up
to 10 seconds.
Rockwell Automation Publication 1756-RM006K-EN-P - November 2018
Action Taken
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
The instruction does not execute, but does validate input
parameters.
EnableIn and EnableOut bits are cleared to false.
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.
Chapter 1
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