I need to convert a pulsing (off,off,off,on,off,off,off,...etc.) signal to a steady on or off input to an allen bradley PLC/5. if the pulse stops,(either on or off) I need to reverse the state of that imput. (If any of you are in the mining industry, think about a slip/sequence switch, without the BWI Eagle.)
I can do this, BUT, when I look at the resulting ladder, and consider that a first year maintenance guy will have to troubleshoot it, I do not want to get called at three in the morning to explain ladder logic.
Whoever shows me the simplest way to program this, I will name my next son after them.
PS:
I am 50 years old and recently divorced from the third wife so, in all likelihood, you will be doing this exersize for the pure enjoyment of it, not any resulant legacy.
Full Version: This HAS to be easier than I am making it...
If the pulse is of a steady time frame do the following.
Fire an on delay timer with 2 parallel contacts of the pulse (NC and NO), setting the timer's set value long enough so it doesn't turn on when the pulse is ... ehm pulsing
When the pulse stops and the contact is either on or off, your timer will run to zero and turn on.
Use the timer as the executing condition for what you want to do.
Dunno about your maintenance guys but shis should give you an extra hour sleep at least
p.s. I'll be expecting a birth announcment card
Fire an on delay timer with 2 parallel contacts of the pulse (NC and NO), setting the timer's set value long enough so it doesn't turn on when the pulse is ... ehm pulsing
When the pulse stops and the contact is either on or off, your timer will run to zero and turn on.
Use the timer as the executing condition for what you want to do.
Dunno about your maintenance guys but shis should give you an extra hour sleep at least
p.s. I'll be expecting a birth announcment card
| QUOTE |
| Fire an on delay timer with 2 parallel contacts of the pulse (NC and NO), |
Don't think that will work, the input will be in one or the other states every scan, so the timer will time out like it was an unconditional rung.
I think you will need to use two timers, one for OFF, and one for ON, THEN parallel the done bits to activate a bit. See Below:
| QUOTE (Ken Moore @ Jul 14 2005, 10:09 AM) |
| Don't think that will work, the input will be in one or the other states every scan, so the timer will time out like it was an unconditional rung. |
Ehmm right you got a point, you mean the timer will run to zero any time because one of the contacts is always true.
Well... Ken Jr. sounds good eh!
Ken,
That was the direction I was originally going.
Gerry, at plcs.net came up with a really elegant solution, though.
Thanks guys.
That was the direction I was originally going.
Gerry, at plcs.net came up with a really elegant solution, though.
Thanks guys.
| CODE |
PULSE ----||-----------+------(OUTPUT) | OUTPUT TIMER | ----||----|\|----+ PULSE ---|/|------------------[TIMER] |
Just so we can all learn.
Very inventive!
The timer in Gerry's solution must be a TOF.
TON will not work.
It actually looks like this.
Input B3/0 T4:0
-+--] [------[ONS]--+----------------------------(TOF)--
| |
| Input B3/1 |
+--]/[------[ONS]--+
T4:0/DN Output
----] [-------------------------------------------( )---]
TON will not work.
It actually looks like this.
Input B3/0 T4:0
-+--] [------[ONS]--+----------------------------(TOF)--
| |
| Input B3/1 |
+--]/[------[ONS]--+
T4:0/DN Output
----] [-------------------------------------------( )---]
How about this?
Wild,
That looks good...
But I still like Gerry's better. I would post a screenshot of it, but I haven't been successful.
That looks good...
But I still like Gerry's better. I would post a screenshot of it, but I haven't been successful.
I still can't get an image posted, But maybe this will work.
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