How To Use The Pid Pressure Control; Figure 67 The Simplified System Diagram - Edwards GXS Series Instruction Manual

9.11 How to use the PID pressure control

The pump has a built‑in PID pressure control and auto tune feature that can adjust the
dry pump speed when the pump is on‑process so that the pressure reading of the
pressure sensor matches the supplied PID setpoint. We recommend that the PID is auto
tuned after the PID setpoint is adjusted.

Figure 67 The simplified system diagram

Classical PID equation
Where:
u is the control signal.
e is the control error.
K is the gain for a proportional controller.
c
T is the parameter that scales the integral controller.
i
T is the parameter that scales the derivative controller.
d
t is the time taken for error measurement.
b is the set point value of the signal, also known as bias or offset.
On the pump, the Kc, T
the user or the pump can perform an auto tune that calculates these parameters based
on the response of the system at the setpoint pressure.
The pump PID pressure control sequence is designed to work with our strain gauge or
active Pirani gauge (available as accessories). Due to inaccuracies in the gauges, we do
not recommend trying to control below 20 mbar with a strain gauge. Refer to
different gauge
The following menus are used by the PDT to configure and use the PID functionality.
M58800880_H - Pump display terminal
and T parameters and the time constant can either be set by
i d
on page 149 to use a different pressure sensor.
Page 148
Using a