Hello, today i have one job, but i can’t do that. So my job is: The trigger is activated, but the signal must not disappear for a certain set time. I must delay the signal, but all timers when the trigger is active immediately coil is active. Trying to do with ladder but unsuccessfully. The trigger is rear switch with NC contact. Maybe someone can help?
Ladder
- Thread starter puokis
- Start date
MiguelMurcia
Member
Trig.q
--| |-------------------(out1)
out1 ton.q |
--| |----|/|----|
out1
| | ----- ton
--| |-------------------(out1)
out1 ton.q |
--| |----|/|----|
out1
| | ----- ton
GaryS
Member
Use an OFF Delay timer
the .DN bit will will stay on for the time delay preset time
the .DN bit will will stay on for the time delay preset time
drbitboy
Lifetime Supporting Member
What environment? Tia? Rslogix/studio 5000? Schneider? Something else?
Can you draw a contact tracer/timing diagram, that is how the input and the output change vs. time?
What happens if the input goes from 0 to 1, and the output goes to 1, the input goes back to 0, but while the delayed output is still 1 the input goes back to 1 again? Does that extend the time the output should be 1?
I think @GaryS is right about the TOF, but the expected behavior is not clear yet; a contact tracer would help.
Can you draw a contact tracer/timing diagram, that is how the input and the output change vs. time?
What happens if the input goes from 0 to 1, and the output goes to 1, the input goes back to 0, but while the delayed output is still 1 the input goes back to 1 again? Does that extend the time the output should be 1?
I think @GaryS is right about the TOF, but the expected behavior is not clear yet; a contact tracer would help.
drbitboy
Lifetime Supporting Member
What starts the "set time?". Is it the rising edge of the input? Or is it the falling edge of the input?
What does "back to normal" mean?
What should happen if the input is still 1 when the "set time" expires?
The problem definition is not clear yet.
Also, if you have attempted to solve this, please show your code, and say how the behavior of your code is different from the behavior you want to see.
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Now that reads like a pulse timer. But his part throws me off:
" I must delay the signal, but all timers when the trigger is active immediately coil is active." That tells me you are looking for on delay.
Unless you are looking for both, first on delay then after times out you want to the ouptubtob on for a specific period then off, pulse timer.
Last edited:
drbitboy
Lifetime Supporting Member
Dear OP/@puokis: this is what I mean when I say the process and the desired behavior are not well understood yet, so it is hard to help you.
If the desired behavior is a "pulse extender" i.e. "pulse stretcher," then the following might work, assuming the duration of trigger is short:
Code:
Trigger tof.DN
-------] [-----]/[-----[TOF tof]--tof is the data structure that holds the state of the TOF timer (tof.DN, tof.ACCumulator, tof.PREset, etc.).
tof.DN, which may be tof.Q in non-Allen-Bradley PLCs, is the output "stretched pulse," that is initiated by a rising edge of the input [Trigger]. Setting tof.PRE (tof.Preset) is up to you.
Phrog30
Member
Everyone is so gullible. Sounds like homework to me. Show us what you have so far, then ask questions.
The only thing that got me interested is the guessing otherwise it would've been more of the same. I mean, "The trigger is rear switch with NC contact", you don't get that everyday
drbitboy
Lifetime Supporting Member
And do you really believe you were the first to think that?
Phrog30
Member
From the comments, yes
drbitboy
Lifetime Supporting Member
Well, that was not the case because I considered it early on. That's one reason I asked to see any attempts at a solution by the OP.
This is either a homework problem or an ESL problem; I still don't think we understand what behavior they are trying to achieve. Maybe it's the TOF, maybe not.
I wonder if it would work better if they typed it in their native language into Google translate, then it might be clearer, or maybe that has already been done.
@puokis: I am not criticizing your English, it is certainly better than my Lithuanian. But we do need a clear description of the problem, e.g a drawing or schematic or timing diagram of desired behavior, which should be language-neutral.
Also, if this is a homework problem then you should state that, because it is more important that you learn by doing than pass the course using plagiarism.
drbitboy
Lifetime Supporting Member
@puokis: this is what a contract trace/timing diagram looks like.
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