National Instruments PID Control Toolkit 371685C-01 - Manual (Page 36)

Glossary
© National Instruments Corporation G-5 LabWindows/CVI PID Control Toolkit User Manual
R
ramp The total (transient plus steady-state) time response resulting from a sudden
increase in the rate of change from zero to some finite value of input
stimulus.
reentrant execution Mode in which calls to multiple instances of a function can execute in
parallel with distinct and separate data storage.
S
s Seconds.
setpoint (SP) An input variable that sets the desired value of the controlled process
variable.
span The algebraic difference between the upper and lower range values.
T
time constant (T) In process instrumentation, the value T (in minutes) in an exponential
response term, A exp (–t/T), or in one of the transform factors, such as
1+sT.
trapezoidal integration A numerical integration in which the current value and the previous value
are used to calculate the addition of the current value to the integral value.
V
V Volts.
W
windup area The time during which the controller output is saturated at the maximum or
minimum value. The integral action of a simple PID controller continues to
increase (wind up) while the controller is in the windup area.