WATER LEVEL CONTROL PROCESS
Original post on the Facebook group Industrial Automation Using PLC and SCADA by Romel Roy. The inputs are 4 NO switches: push button START, pushbutton STP for the stop function, high and low level sensors, that is HLS and LLS. The outputs are 3 NO switches: pump motor (KPM), water inlet electrovalve EV1, and water outlet/drain electrovalve EV2. So we actually have I/O = 4/3. Initial condition: the tank is empty. Initially, the START pushbutton is pressed on, the motor starts and EV1 opens. The water level in the tank raises up until HLS is activated. Accordingly the motor turns off and EV1 closes. Next, EV2 opens and the water level is lowered. Eventually LLS will become deenergized at which point the process is reinitiated. When pressing on the STOP pushbutton the process will stop. We first draw the GRAFCET diagram for the process stated above, The state 0 is the machine's rest state. The transition condition to state 1 requires that we press on the START pushbutton and ...