Ok, first question was lame.....ended up starting from scratch.

New challenge.

I have a an output to be turned on with a NO contact input that I'm latching on with the contacts of the output.

There is a NC contact between the NO input and the OP. When the NC contact opens, the output must turn off, however, when the NC contact re-closes, I need the output to come back on....without reclosing the NO switch.

I'm stuck.

I moved this to the PLC direct forum, you should get more responses here.


Ken

Ok, I might be experencing a caffene surplus problem.

Does this mean. I have a NO contact in the field that goes to a PLC input. I need this input to "seal" or "latch" the PLC output on with the logic?

Or does this mean. I have a NO contact in the field and I want to turn on a output and wire this output to the input so it stays on?




Your stuck? I have no Idea what an "OP" is. Is that an Operator Panel?

It might be just the caffene talking but you appear to be using hard wire relay terminology - lingo.

I would like to help but I can't make sense of your question. But it might be just me and my caffene overdose


Edit: I just had another cup of coffee.

Are you saying you have a NO contact in the field that is connected to a PLC input. When this contact closes (momentary) I want a PLC output to turn on, then when it closes (momentary) again I want the PLC output to turn off?
Vaughn

i am guessing that he is using NO and NC contacts with an output
to create start/stop logic and he used term "latch" instead of "seal in",
something like:

[attachmentid=5873]

the problem he has is that stop condition (NC contact) clears the output
and input doesn't come on until next cycle.

if so far this is correct, there are few things that need to be done:
- introduce buffer (memory bit) and use it instead of output in the original rung.
- create new rung and use buffer bit (NO) and stop bit (NC) to drive output
- in first run replace address on NC contact with something different
(like cycle complete or whatever is suitable in his case)

[attachmentid=5874]

oh, thank you!

Panic Mode,
Thank you, you've drawn it exactly as I described.

From your drawing, I need I:1 to be a momentary switch that actuates O:2. When B3:0 turns on (opens), O:2 turns off. When B3:O turns off, (re-closes), O:2 comes back on without I:1 closing again.

I don't think I understand how your solution works though.

If B3 is turned on and 'sealed in' , that's fine. On the new rung however,
1) I don't see how the output ever comes on since both a NO and a NC are in series for the same output (B3), and
2) while B3 is on, and I1 turns off, how would B3 turn off?

My guess is that I don't understand how your 'Buffer' output coil (or memory location, or whatever it is) works.

I am not sure what the numbers under the contacts/coils mean, are they relevant to the operation? (ex: 15, 1746-O*16)

Thanks!

I got it!

FYI, I'm using Directsoft 5....

I think I may have used your advice, nevertheless, here's what I did...

I kept the NO (X1) input sealed with the coil output (Y1) and in parrallel with that, I put a NO contact (C0) for a PD (positive differential, or one-shot)....that in series with my NC contact (X3) turned on my output.

On the next rung, I put the NO side of X3 to turn on C0.

If that doesn't make sense, and you really want to know, I'll try to put in a diagram here, I just don't know how yet...

Thank you for your replies!

just make a screenshot (press PrtScrn button), then
paste into your graphic program of choice (I usually run IrfanView),
crop it (in IrfanView just select part of interest with the mouse, then use Ctrl+Y)
save it as one of the formats supported on forum (JPG is fine)
then attach it in new post using "Browse" and "Add this attachement" (below text box of your new post)

[attachmentid=5889]