In PCS 7 V5.1 onwards it is possible to optimize controllers using the commissioning tool "PCS 7 PID Tuner". The tool makes measurements to determine the process parameters and then suggests the optimum settings for the controller. If required, you can apply these settings immediately.
You can optimize controllers of the "PCS 7 Library", "PCS 7 Advanced Process Library" V7.1 onwards and function-compatible controllers. In the case of step-action controllers, it is also possible to determine the motor actuating time.
- The PCS 7 PID Tuner software is installed on the ES. You can install the tool with the PCS 7 general setup.
- The necessary license is installed. In PCS 7 V7.1 onwards you do not need an additional license for the PCS 7 PID Tuner.
- The CFC chart is compiled and loaded into the AS.
- There is an online connection between the ES and the AS.
- The following is known about the control loop:
- Process behavior (with or without integral part)
- Status of the control loop (manual or automatic)
- Working point of the controller
- Controller type (PID, PI or P controller)
The instructions below show you how to use the PCS 7 PID Tuner taking the example of a continuous PI controller.
Additional information is available in the relevant readme file and in the Online Help of the PCS 7 PID Tuner.
A practical example of how to operate using the PCS 7 Advanced Process Library (APL) is shown in the document entitled "PID Control with Gain Scheduling and PID Tuning" (Entry ID: 38755162).
- Please note that by optimizing you are interfering with the plant process. If there is interference in a process, this is indicated in the optimization step concerned. You must be aware of the possible consequences.
- Make appropriate arrangements with the operating staff before optimization.
- Monitor the process constantly on the curve recorder during optimization.
||Prepare the controller for optimization|
Before optimizing you must switch the controller to "Optimize" mode. You can set this in the CFC chart on the controller block or on the OS faceplate.
You set the "OPTI_EN" input to "Enable" on the block in the CFC chart. The input is hidden by default. On the faceplate you set the "Enable Optimiz." option in the "Parameter" view.
Fig. 01: Preparing the controller for optimization
||Start the PCS 7 PID Tuner|
Select the controller block and start the tool from the CFC chart using the menu command "Edit > Optimize PID controller...".
Fig. 02: Starting the PID Tuner
||Parameterize the curve recorder|
To adapt the display to the process conditions, you stop recording and click the "Settings..." button.
Fig. 03: Parameterizing the curve recorder
||Start controller optimization|
Click the "Start Controller Optimization" button.
Fig. 04: PID Tuner
||Measured value acquisition (Steps 1 to 5)|
In Steps 1 to 3 you define the conditions for measured value acquisition. The values of the control path are acquired in Step 4. Monitor this on the curve recorder. Then you can cancel process stimulation.
- Select process behavior (with or without integral part)
- Select the operating mode (manual/automatic) and input the starting point for the jump stimulation
- Input the jump stimulation, new setpoint value
- Measured value acquisition
- Cancel process stimulation
Fig. 05: Measured value acquisition
||Controller behavior and result (Steps 6 to 8)|
You select the controller behavior and type in Steps 6 and 7. In Step 8 you simulate the control loop with the optimized controller parameters. You can test with this with different jump sizes and controller parameters.
- Input of controller behavior (optimum disturbance behavior / optimum master control behavior)
- Result and selection of controller type (PID/PI/P)
- Simulation of the controller loop with the optimized parameters
Fig. 06: Result parameters
Fig. 07: Result diagram
||Set the controller (Step 9)|
In this last step you can select whether the old or new settings are to be applied. Click the "Finish" button to end controller parameterization.
- Selection of the controller parameters (old/new)
Fig. 08: Loading the optimized parameters
||End PID Tuner|
The controller is now parameterized with the new settings. End the PID Tuner by clicking the "End and save" button. The controller is reset to its original operating mode.
The pictures in this FAQ were created with SIMATIC PCS 7 V7.1.