Glossary
LabWindows/CVI PID Control Toolkit User Manual
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output limiting
Preventing a controller’s output from traveling beyond a desired maximum
range.
overshoot
The maximum excursion beyond the final steady-state value of output as
the result of an input change.
P
P
Proportional.
PD
Proportional, derivative.
PI
Proportional, integral.
PID
Proportional, integral, derivative.
PID control
A common control strategy in which a process variable is measured and
compared to a desired setpoint to determine an error signal. A proportional
gain (P) is applied to the error signal, an integral gain (I) is applied to the
integral of the error signal, and a derivative gain (D) is applied to the
derivative of the error signal. The controller output is a linear combination
of the three resulting values.
PID controller
A controller that produces proportional plus integral (reset) plus derivative
(rate) control action.
process gain (K)
For a linear process, the ratio of the magnitudes of the measured process
response to that of the manipulated variable.
process variable (PV)
The measured variable (such as pressure or temperature) in a process to be
controlled.
proportional action
Control response in which the output is proportional to the input.
proportional band (PB)
The change in input required to produce a full range change in output due
to proportional control action. PB = 100/
K
c
.
PSI
Pounds per square inch.
