KROHNE Summit 8800 Vol 2 - Manual (Page 153)

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08/2013 - MA SUMMIT 8800 Vol2 R02 en
SUMMIT 8800 VALVES 11
Figure 163 Select the digital valve ID
11 .3 PID
A PID controller (proportional integral derivative) is a closed control loop to steer an output to a
desired value (the setpoint). It uses a feedback system to calculate the difference between the
output and the setpoint. The PID calculation tries to minimize this difference by adjusting the
valve. Important is to set the correct PID parameters to optimize the error and speed.
An analog output will be used to control the valve, either as a direct output value of the PID
algorithm or as a percentage of the maximum value of the PID output. The process value to be
controlled can be any analog value, such as temperature, pressure or flow. The setpoint for the
PID can be controlled viamodbus or via the front panel of the flow computer.
Figure 164 PID control loop
The PID valve has the following parameters:.