Use CC Function Block to Control temperature

This is an example of how you could use the Coordinated Control function block to control the temperature in a process.

Temperature Example Explanation

Manipulating the PV at the setpoint is the top priority. The high pressure steam and cooling are selected as the most active actuators. At steady state, the same two controls should assume their target values: CV3 at 10% and CV2 at 0%. CV1 will assume any value needed to maintain PV at the setpoint; therefore, its target value is irrelevant since manipulating the PV at the setpoint is a higher priority control objective. Target CV priorities and target CV values can be changed on-line.

The CC function block calculates CV1, CV2 and CV3 such that the control goals are accomplished in the following order of importance:

At this point, you have completed the basic configuration. You did not configure the built-in tuner. The control variable is ready to be put on-line in either auto or Manual mode. For tuning, the default settings will be used. Refer to CC Function Block Tuning.

If you do not know the process models, you need to identify the models and tune the function block by using the built-in tuner (modeler) for the function block to operate correctly in the Auto mode.

The function block uses first order lag with deadtime internal process models and first order filters (total of up to twelve tuning parameters) to calculate the CV's. Each CV is calculated such that the process variable (PV) follows a first order lag trajectory when approaching the setpoint value.

Speed of response depends on the value of the response time constants. The smaller the response time constants, the faster the control variable response will be. The response time constants should be set such that the PV reaches the setpoint in reasonable time based on the process dynamics. The larger the response time constants are, the slower the control variable response will be, but the control variable also becomes more robust. See the tuning section for more details.

In the Manual mode, the control variables (CV) are set equal to the operator-entered or program-generated CVnOper or CVnProg parameters. For the Manual to Auto mode bumpless transfer and for safe operation of the control variable, the CV rate of change limiters are implemented such that CV's cannot move from current states by more than specified CV units at each scan.

To limit the CV rate of change:

Rate limiting is not imposed when control variable is in Manual mode unless CVManLimiting is set.