Making large time intervals - PLC

If it’s necessary to make a bigger time interval of 999.9 seconds (9999x0.1s) two linked timers, or a timer and a counter can be used as in this example. Counter is set to count to 2000, and timer is set to 5 seconds which gives a time interval of 10.000 seconds or 2.77 hours.

By executing a condition at PLC input, timer begins to count. When it reaches the limit, it sets a flag TIM001 which interrupts the link and simultaneously resets a timer. Once 5 seconds have run out, flag TIM001 changes its status to ON and executes a condition at the counter input CNT002.

When a counter numbers 2000 such changes in timer flag status, TIM001 sets its flag CNT002 which in turn executes a condition for PLC to change status to ON. Time that has elapsed from the change of PLC input status to ON and a change of PLC input status to ON comes to 10.000 seconds. Ladder Diagram:


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