#31 - Siemens TIA Portal PID control with PID_Compact

Siemens PID_Compact and CONT_C blocks are widely used in the Process industry for applications with proportional integral derivative (PID) controllers. In this post we will do an example with PID_Compact v2.2.

In this example, a system of a stone conveyor belt is simulated, which has a speed from 0m/min to 150m/min (CV) driven by a 3 Phase motor and inverter. 

Speed feedback (PV) is measured by an encoder. In the HMI it is possible to enter the Set-Point (SP) speed in m/min. The controller chosen was of the PI (Proportional Integral) type, which is widely used in the industry for its properties of precision and stability.

On this page it is possible to change the PI controller operating mode, from Manual to Automatic. The automatic mode can be used, for example, during a pre-tuning phase.

Basic settings: Controller Type: Velocity [m/min]

Selecting the Inputs and Outputs parameters that in this case are via simulated software. If the IOs were hardwired to analog cards, the Input_PER and Output_PER options would be chosen:

Entering speed limits: Process Value Limits 150m/min, 0m/min.

These are the parameters of the PID controller, which can also be seen in the DB created within the Technology objects DB4. From the HMI screen, it is possible to write the value of Proportional Gain and Integral action time.

PID parameters: K: 5, Ti: 20

The oscilloscope is very practical to simulate responses to SP variations, as in the example below, we can see the system response when lowering from 85m/min to 20m/min, and increasing from 20m/min to 55m/min, with different values gain. The first two changes were made with a gain of 1, and the last two with a gain of 5.

Note: the PV values, which represent the encoder reading, are simulated with the Siemens SLI_PROC_C block.