Counting Down a Timer?

henno2000 · Jan 7, 2008

Hi, I am wanting to know if this is possible using S7:

When a 1 hour timer has been triggered (count up timer), to detect when the 1 hour timer is 5 seconds from the end of the cycle (IE - 59 minutes and 55 seconds), in order to trigger another event.

If someone could provide a logical explanation if this is possible/not possible, it would be greatly apprecaited.

Regards,
henno2000

PeterW · Jan 7, 2008

If your using normal ladder timers, you would have two outputs, BI (Integer) and BCD formats.

You could use these outputs by assigning words to them, you could then compare to whatever preset values you want.

manmeetvirdi · Jan 8, 2008

Also
You can run another timer of that much time.
If 1 hour time is variable then you can subtract 5 seconds and run another timer.

henno2000 · Jan 8, 2008

manmeetvirdi said:
Also
You can run another timer of that much time.
If 1 hour time is variable then you can subtract 5 seconds and run another timer.

Could you give an example of what you mean?

Regards,
henno2000

manmeetvirdi · Jan 8, 2008

If timer T0 is running for 1 hour
Then run T1 for 1 hour and 55 min

Both should be triggerd at same instant.

Using FC40 would be usefull if 1 hour time is not fixed.

STL??? · Jan 8, 2008

I would increment a Integer using the CPU 1 sec clock pulse, then compare the integer count with your desired time (3595 pulses).

Once the desired time is =>I ~ trigger the event you want to happen.

Then reset to 0 at 3600 pulses.

TConnolly · Jan 8, 2008

Simple math and comparrison
(Elapsed Time) < (Timer Preset -5 )

1 hour is 3600 seconds long.

Another way of arranging the math and comparrison is
(Timer Preset - Elapsed Time) < 5

Counting Down a Timer?

henno2000

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STL???

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