3 . Timer Design Examples Control Program: X3 Y0 X1 Y1 Y2 X2 X0 T2 X3 T1 Flashing Circuit X0 T1 X4 RESET Alarm Lamp Y3 X3 Y4 Alarm Program Description: z When the water is at normal level: X0 = ON, X1 = ON, X2 = OFF and X3 = OFF. Therefore, Y0 and Y2 will be OFF. Both the drainage pump and the feeding pump will not work. z When the water is lower than the normal level, X0 = ON, X1 = OFF, X2 = OFF and X3 = OFF. Because X1 = OFF, Y1 will be ON. The feeding pump will start working. z When the water is below the lowest of alarm level, X0 = OFF, X1= OFF, X2 = OFF and X3 = OFF. Because X1 = OFF, Y1 will be ON. The feeding pump will start working.
In addition, because X0 = OFF, the flashing circuit will be activated, which makes Y3 = ON and Y4 = ON, The alarm lamp will flash and the alarm will ring. z When the water is above the normal level, X0 = ON, X1 = ON, X2 = ON, X3 = OFF. Because X2 = ON, Y2 will be ON. 2# drainage pump will drain water from the fishpond. z When the water is above the highest of alarm level, X0 = ON, X1 = ON, X2 = ON, X3 = ON. Because X2 = ON, Y2 will be ON. 2# drainage pump will work. In addition, because X3 = ON, Y0 will be ON. 2# drainage pump will work. Besides, the alarm circuit will be executed, which makes Y3 = ON and Y4 = ON. The alarm lamp will flash and the alarm will ring.
z When Reset is pressed, the NC contact X4 will be activated. Y3 = OFF and Y4 = OFF. Both the alarm and the alarm lamp will stop working. DVP-PLC Application Examples 3-8 TMR T1 K5 TMR T2 K5