Detailed formulas
Original instructions
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Explanation of formula variables
Meaning of the variables in the following formulas:
Variable
Meaning
is the time differential between the current cycle and the previous cycle
System deviation (SP - PV)
System deviation value from the current sampling step
System deviation value from the previous sampling step
OFF
Offset at the output of the P-controller
Y
Manipulated variable
Y1
Y of the master controller
YI
I component
YP
P component
Overview of the calculation of the control components
There now follows an overview of the varying calculations on control components and outputs for the various modes:
Automatic operating mode
The output signal Y of the cascade controller is:
The input signal SP2 of the sub controller is:
The integral component Y1 of the master controller for the automatic mode is determined as follows:
The I component is formed according to the trapezoid rule.
Manual mode
The output signal Y of the cascade controller is:
The input signal SP2 of the sub controller is:
The integral component Y1 of the master controller for the manual mode is determined as follows:
Halt mode
The output signal Y of the cascade controller is:
The input signal SP2 of the sub controller is:
The integral component Y1 of the master controller for the halt mode is determined as follows:
Fixed setpoint control
The output signal Y of the cascade controller is:
The input signal SP2 of the sub controller is:
The integral component Y1 of the master controller for the fixed setpoint control mode is determined as follows: