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Process control instructions
PID_FB_DUT
This implementation allows you to access the F355_PID instruction via the structure PID_DUT.
Description
This structure defined in System Libraries / FP Library / DUTs contains the following parameters
(for details, please refer to the DUT PID_DUT):
Data types
Input variables (VAR_INPUT):
Variable
Automatic
Input/Output variable (VAR_IN_OUT):
PidDut
In this example the function has been programmed in ladder diagram (LD) and structured text (ST).
Example
GVL
In the global variable list all global input and output values are declared that are used to program
the function. The addresses are depending on the respective PLC-Type.
POU header
All input and output variables used for programming this function have been declared in the POU
header.
954
PID processing instruction
Data type
Function
BOOL
FALSE: Manual setting of MV possible
TRUE: Automatic PID controlled MV
PID_DUT
You may not enter the DUT PID_DUT a second time under DUTs of the
current project.
The value for MV can be assigned externally either when the program is
initialized or when the value of Automatic is FALSE.
In order to achieve maximum resolution and minimum dead time beyond
LowerLimit and UpperLimit, these values should, if possible, cover the
entire range of 0–10000.
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