How can I create a off delay?

I have put this question out there before, but still having troubles. My PLC directsoft logic, does not support any tof delay timmers, is there a simple way I can create one with missalaneous instructions?
Help would be great
Thanks,
DM

Hi.
Maybe you would like to put a new rung with a TON timer and set to energize a memory output. Use the N.C contact of that memory output to your required instruction, so to simulate a TOF function.

Regards
Sherine T.

There is no OFF DELAY TIMER, you have to manipulate an ON Delay or TMR.
In the following pic when start is pushed timer will start and C0 will be latched ON. In next rung Y0 will be on until timer is DONE, when timer is done then C0 will unlatch and Y0 will go OFF.


C0 is needed because T0 -|/|- will always be on when timer is NOT DONE.

darrentpi,

The usual "On Delay" Timer (TON in RSLogix) starts timing when the rung goes from false to true. The "Off Delay" Timer is the opposite: it starts timing when the rung goes from true to false. The simplest way to simulate this is to use what you have, the TMR (On Delay) instruction, but use a STRN (Store Not)or ANDN (And Not)contact in front of it, so that when an input goes from on to off, the timer starts timing.

The next problem is that if your rung starts off to be false, then the timer will start right away, but you may not want it to start until your Input condition goes from true to false. The solution is to put an "inhibit" contact at the front of the timer rung (or on the next rung where you use the TMR bit), which does not go true until just before the timer is needed.

Of course this "inhibit" bit gets us right back where we started: You can get the same effect by simply using a bit which goes to True when your input condition goes from On to Off. Put this bit in front of a TMR timer, and you are done.

C0 is needed because T0 -|/|- will always be on when timer is NOT DONE.

Click to expand...

What I do is use a Greater than contact for the current timer value instead of using another bit.i.e., TA0>1 works great as a latch with the done bit used to unlatch it.

Depending on which processor he is using, he could use the Positive Differential bit

to start the timer. This way the timer will not start if the input is true until is goes false and then true again.

Bob

Ok

darrentpi try this in your 405 it works in a 105.




:site:

Yeah Bob, thats more or less what I do depending but I was just offering an idea for him to elaborate upon. There are alot of ways to manipulate a timer and its accumulated value.

Wow, can we make this more complicated? Set, reset, differential contacts, comparisons?!?!...

No stages needed, Bob?...

I prefer the simple off-delay timer Tom showed in THIS post... :nodi:

Works just like a TOF instruction...



-Eric

Eric Nelson said:

No stages needed, Bob?...
-Eric

Click to expand...

Trust me. I thought about it...

Bob

Well!!

Well Eric you could have posted that earlier and saved alot of head scatching. That`s to simple.

:site:

Thomas,

Your off delay scheme is proof positive that there 1000 ways to skin a cat....all at the same time.

too funny....