1. Basic Program Design Examples 1.15 Forward/Reverse Control for the Three-Phase Asynchronous Motor Forward Forward Reverse Reverse Stop Control Purpose: z Controlling the motor to run forward when Forward is pressed, run reverse when Reverse is pressed and stop when Stop is pressed. Devices: Control Program: X0 T0 X1 X2 Y1 Y0 Y0 X1 T1 X0 X2 Y0 Y1 Y1 Program Description: z X0 = ON when Forward is pressed. After 1 second, contactor Y0 will be enabled, and the motor begins to run forward. On the other hand, X1 = ON when Reverse is pressed. After 1 second, contactor Y1 will be enabled, and the motor begins to run reverse.
Besides, Y0 and Y1 will be disabled and the motor will stop running when X2 is pressed. z The two timers in the program are used to avoid the interphase short-circuit when the motor changes its running mode. The short circuit may occur if another contactor is enabled instantly while the electric arc in the disabled contactor still exists. DVP-PLC Application Examples 1-18 Device Function X0 Forward button of the motor. X0 will be ON when pressed X1 Reverse button of the motor. X1 will be ON when pressed X2 Stop button. X2 will be ON when pressed. T1 1 sec timer T2 1 sec timer Y0 Forward contactor Y1 Reverse contactor TMR T0 K10 TMR T1 K10