A pH process control embedded on a PLC using Fuzzy Logic

The present work shows the design and implementation of a controller based on Fuzzy Logic for pH regulation using an S7-1200 Programmable Logic Controller (PLC) as a processing element. The inputs of the controller are the current error (desired pH - current pH) and the rate of change in error (current error - previous error). On the other hand, the output is given by the activation time of an on-off dosing pump, which was adjusted to a constant flow of 2.5 liters per hour. The controller calculates the time that the pumps must be on or off so that the process variable reaches the desired value. A Delta Human Machine Interface (HMI) are used to acquisition data and process parameters configuration.