Timer down

Hi,

As I can make a TIMER where the Accumulator. ACC is down,

eg T4: 0.ACC = -250
-254
-253
.
.
.
. etc.

I am using RSLogix 500.

Thanks in advance

what is the question

I need a TIMER DOWN...

If you make the ACC negative you will fault the processor. Since a timer is not a device, it is a computer instruction, it calculates the elapsed time from a reference time that is stored in the least significant byte of T4:X.0 and so it can only count up.

You can compute the amount of time remaining by subtracting the ACC from the PRE and storing the value in an N word. The value stored in the N word will count down from the preset to zero.

Thanks..!!! this is the best forum

If you actually want a negative number subtract the PRE from the ACC.

?

Why negative number just use a TOF if you want it to stay on for x length of time then go off.