Why is the IDC delay on / off time [ms] limited at 3276750 in version 7
(and unlimited in version 6)
The value you see is dependent on your cycle time.
The project check limit is solving a problem in earlier version that it was possible to enter too high values that did not work.
If you need a longer time delay, you can built it with a TMR channel instead.
Customer support service by UserEcho