7.2 Making large time intervals
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 IR000.00 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 IR010.00 to change status to ON. Time that has elapsed from the change of IR000.00 input status to ON and a change of IR010.00 input status to ON comes to 10.000 seconds.
Ladder Diagram:
