Need to pause an output on an AB 1000

I need to start a timed output with a P.B. using an AB 1000 and be able to pause it at any time with a P.B., have it then restart it's remaining preset time period with the same P.B. Such as the PLC preset time is 4 hours, pause it for any length of time then come back and reset it and the total run time would only be for 4 hours. I am new at this and only can program contacts, outputs timers and counters as yet. Any help would be appreciated. THANKS

That's a good question, Leon. With the MicroLogix 1000 there is an easy answer; I think it will be instructive for one of the other experts to show how this is done when there is not a specific instruction for the function.

In the MicroLogix and SLC-500 controllers there is a variation on the TON timer instruction callled the Retentive Timer On (RTO).

This timer retains it's accumulated value even when the input conditions become false, or the controller is powered down. It doesn't reset until you use a RES instruction in logic.

The bit that indicates that the timer is running is called the "Timer Timing" bit, which is addressed with the mnemonic ".TT".

Using the same pushbutton to start, pause, and reset the timer is a simple flip-flop logic, and I'll leave that to your research on this site (there is an excellent tutorial to which I refer often).

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Question to other A-B students; what is the upper limit on time in the above example ?

Thanks Ken

This is my first experience with this site, and it is Great, I will try what you suggested. Thanks for the print example also. This site is what the world is all about, people helping people.

Leon

gosh ken is fast - see if this will work - you didn't say how you wanted to reset it so i took a guess - once the time is up, just push the button to go again -

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edit PS - somehow i got the impression that leon is not a student - if he is, i'm sorry for the silver platter approach - i didn't mean to thwart the educational process -

Ron,

You both are fast. I am a student in this area. Been an electrician for 40 years though and do not do a lot of PLC work since our customers have on site people that do most of that. Thanks for the silver platter approach.

Leon

Ken, seeing as no one else has answered the question about the upper time limit on the RTO in your example I'd like to give it a go. Is the upper limit 9 hours, 6 minutes and 7 seconds?

Gold star for Doc.

9 hours = 32400 seconds
6 minutes = 360 seconds
7 seconds

= 32767 seconds.

32767 is the decimal equivalent of the binary number
"0111 1111 1111 1111", which is the highest value a MicroLogix 1000 can store in a 16-bit Signed Integer.

There are, of course, numerous ways to trade accuracy for duration.

Ken, Doc & Ron you guys have helped me a lot today (my first day on this site) I thought the question about the time related to the upper limit was the preset time which would have been 4 hours not how much time could be entered, but now I know that also.

Thanks

Fun with timers and counters

Leon,

Heres' a little exercise for fun, try this.
Use a timer with a .01 second time base. Switch it on or off with the flip flop control circuit. Let it reset itself once per second to drive a counter for the seconds readout. Cascade that counter with another one for the minutes readout. Cascade that counter with another one for the hours readout. Each counter's done bit is used to reset itself. When the hours counter is done, use the done bit for it to reset everything. As you can see,this could be extended to show number of days, weeks, months and/or years. It all depends on the preset value in a particular counter.

Use of a clock to show the time elapsed

jrwb4gbm,

That is what I wish to do also. Do you know of any type clock that could be attached to the outputs to show an operator the elapsed time? I could do this with any type electric clock, but I would have to reset it manually each time. I would like something to reset automatically.

Thanks

Leon

Pause AB-1000

Hey Guys!, I just reviewed the ideas looks good except I have one or 2-questions. In the first example how did U get the bit B:3/0.0 to become a flip flop, and in the second example how did U keep b3:1 latched in if b3:0 unlatched it after the oneshot, which brings up my next question reguarding 2-different ways of unlatching from 2-different rungs? Sorry for sounding so dumb

honest questions - honest answers

I hope I’m not being too presumptuous by answering for Ken - but in his post but he DID say:

... a simple flip-flop logic, and I'll leave that to your research on this site (there is an excellent tutorial to which I refer often).

Click to expand...

He expects the reader to do a “search” on a subject which has been covered many times in the past.

As for B3/1 in my post - it does NOT stay latched on - it is used as a temporary flag bit - it keeps the UNLATCH from turning B3/0 right back off again as soon as we’ve turned it on.

It’s OK to put more than one UNLATCH (for the same bit) in a program - all an UNLATCH really does is write a 0 (zero) into a bit location. And incidentally, it’s also OK to put more than one LATCH (for the same bit) in a program - all a LATCH really does is write a 1 (one) to a bit location.

And if I were in a picky mood today ... you should have said “B3/1” and “B3/0” - the colons in “B3:1” and “B3:0” indicate 16-bit WORD addresses - not BIT addresses. But we all know what you meant.

And you don’t sound “dumb” - because if the same questions weren’t “good ones” then they wouldn’t have been covered so many times before.

Best advice: If you have a processor and the software, program both answers and try them out for yourself. That’s the best way to learn. Ken even left a little “omission bug” in his program - obviously for the student’s educational advancement. Hint: What’s going to happen when the four hour timer gets done?

Pause AB-1000

Thanks for reminding ME!, U-no the old saying LOOK before U LEAP? I guess I leaped, after reviewing it again I-C-U-R right! Thanks for the refresher!

Totally Lost Now

Ken, Ron & TBone,

Neither one of the programs worked. I am not a student in a class trying to get free info for a school project. I am a 60 year old man trying to teach myself something new, that I thought would interest me, the same as I did AutoCAD. I tried other options on the programs with no success. I have very little experience with PLCs the timers, resets etc. but want to learn. It seems you provided information that is not correct to challenge me, but I have very little experience in this area. I teach some electrical code classes and the last thing I do is give a person the wrong info, as that could be hazardous or a life safety issue. I think the same could be true with a PLC program that did not work properly.

Thanks Guys,

Leon