model 2704 controller installation and operation handbook - Soliton

2704 Controller Loop Set Up
9.2. TO SET UP PID PARAMETERS
The PID parameters are Proportional Band, Integral Time and Derivative Time. The
value of these parameters are dependant upon the characteristics of the application under
control. Control stability is also achieved by setting other parameters such as Cutback,
Manual Reset, Relative Cool Gain, Feedforward, etc,. Further information is available in
Chapter 8, Tuning.
For processes where the rate of change varies significantly over the operating range, i.e. nonlinear
processes, a single set of tuning parameters may not be adequate. The 2704 controller
allows three sets of tuning parameters to be held in memory. Each set can be active at
different points in the range to provide best control at different process values. These
transition points are set using the parameters 1/2 Boundary and 2/3 Boundary. This is also
referred to as Gain Scheduling.
A customisable parameter is available in the PID (and PID Aux) pages which provides the
user with additional flexibility when designing a control strategy. This parameter is called
Analogue Value (An Value 1 to 3). It is available for each PID set if Gain Scheduling has
been configured and for each loop configured . It can be ‘soft wired’ in configuration mode
to perform a specific function relevant to the particular process being controlled. Examples
include: Output Power Limit, SP Feedforward Trim, etc,.
Installation and Operation Handbook. Part No HA026502 Issue 1.0 Apr-00 9-3