T The PID Tuner was used to find good PID settings. For that, a step experiment had to be done in a safe way. To ensure safety, we applied the option of a 'PVmax'. That was in this case the maximum pressure above which the step experiment would be stopped and control would resume.
De PID controller was programmed in an Allen Bradley PLC. The PID Tuner software communicated with the PLC via de OPC server of Rockwell Automation (RSLinx Classic OEM).
The figure below shows the results of both old PID settings and new ones.