As from PCS 7 V5.1 you can use the commissioning tool "PCS 7 PID Tuner" to optimize controllers. The tool identifies the control path parameters by measuring and then suggests the optimum settings for the controller. You can apply these settings immediately if you wish.
You can optimize the controllers of "PCS 7 Library" and "PCS 7 Advanced Process Library" as from V7.1 as well as controllers with compatible functions. You can also determine the motor actuating time of step controllers.
- The PCS 7 PID Tuner software is installed on the ES. You can install the tool via the normal PCS 7 Setup.
- The required license is installed. As from PCS 7 V7.1 you no longer need an extra license for the PCS 7 PID Tuner.
- The CFC chart is compiled and loaded into the PLC.
- There is an online connection between the ES and the PLC.
- The following is known about the control loop:
- Process behavior of the control path (with or without integral component)
- Status of the control loop (manual or automatic)
- Working point of the controller
- Controller type (PID, PI or P controller)
How to use the PCS 7 PID Tuner is described below taking the example of a continuous PI controller.
More information is available in the corresponding readme file and in the Online Help for the PCS 7 PID Tuner. A practical operating example is given in the document "PID Control with Gain Scheduling and PID Tuning" (Entry ID: 38755162).
- Please note that by optimizing you are interfering with the system 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 controller for optimization|
The controller must be switched to "Optimize" mode before optimization. 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 PCS 7 PID Tuner|
Select the controller block and start the tool from the CFC chart with the menu command "Edit > Optimize PID Controller...".
Fig. 02: Starting PID Tuner
||Parameterize the curve recorder|
To adapt the display to the process conditions, you stop the recording and click on the "Settings..." button.
Fig. 03: Parameterizing the curve recorder
||Start controller optimization|
Click on 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 patch are acquired in Step 4. Monitor this on the curve recorder. Then you can cancel process stimulation.
- Select process behavior (with or without integral component)
- 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 the last step you can select whether the old or new settings are to be applied. Click on 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 PID Tuner by clicking on 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.