3 . Timer Design Examples Program Description: z This program uses the NC contact T0 as the executing condition of the timer T0. When T0 reaches its set value, 30 sec, it will be activated. The trigger circuit will be executed to change the state of M1. Production line 1 will then start working. z After 30 sec counting, T0 turns ON. The NC contact T0 will be activated. At the same time, timer T0 will thus be OFF, which makes the NC contact T0 to be OFF again. In the next scan period, because the NC contact T0 is OFF, timer T0 will start counting. After 30 sec counting, T0 will be activated and so will the trigger circuit. In this case, M1 changes its state again.
Production line 1 will be stopped and production line 2 will start working. z By using the trigger circuit to activate Y0 and Y1 alternatively, the program makes the two production lines to convey products alternatively. DVP-PLC Application Examples 3-26