COSA Xentaur Xentaur XDTL-HT - Manual (Page 32)

32
PID Controllers
A PID controller is a generic control loop feedback mechanism that attains a process output setpoint
with minimal error. The XTDL-HT™ has four PID controllers. PID controller 1 is reserved for operating
the enclosure heater. User is free to use the other three controllers. The instrument uses the standard
PID form:
where:
MV(t) is the manipulated variable
e(t) is the error = setpoint – process value
K
p
is the proportional gain
T
i
is the integral time
T
d
is the derivative time
With this form, the controller can adjust how the process setpoint is reached by changing the
proportional gain, the integral time, and/or the derivative time. Increasing the proportional gain
decreases the rise time on the process but increases overshoot. Increasing the integral time decreases
the steady-state error but increases the settling time. Increasing the derivative time increases the
process stability. Therefore, it is important that these parameters are set with the right balance to
avoid undesirable error.
Any one of the XTDL-HT™ measurements can be a PID controller input, even the external analog
inputs. The PID controller outputs can be applied to analog outputs and/or relays. This is another
benefit to use XTDL-HT™ for small local control system.
Setup Menu
Variable
Setpoint
Proportional
Integral
Derivative
Variable
Setpoint
Proportional
Integral
Derivative
Variable
Setpoint
Proportional
Integral
Derivative
Variable
Setpoint
Proportional
Integral
Derivative
Channel 1 Channel 2 Channel 3 Channel 4
PID