PLC 5 Problem....need help or guidance

Dexstar · Jul 20, 2005

I have a process that counts parts that come off of a welder. Right now, we have a SQ.D limit that signals when a part passes the limit wire. My problem is, when the limit bounces, it counts that as a part. What are some avenues I can take while still using the limit. I know I can go with a sensor, but I have "some" programming experience. My thought is a OSR instruction, but I've simmed it out and it doesn't seem to be working. Any tips?
BJ

Hydro Power Guy · Jul 20, 2005

You need to "debounce" the sensor by means of a timer.

[XIC]sensor------(TON)--

[XIC] TON.DN-----(Increment part count)--

hd_coop · Jul 20, 2005

Dexstar said:
I have a process that counts parts that come off of a welder. Right now, we have a SQ.D limit that signals when a part passes the limit wire. My problem is, when the limit bounces, it counts that as a part. What are some avenues I can take while still using the limit. I know I can go with a sensor, but I have "some" programming experience. My thought is a OSR instruction, but I've simmed it out and it doesn't seem to be working. Any tips?
BJ

You could program some sort of debounce. Either use your limit switch to start a short timer and use that timer's done bit. Or use a timer that starts when the limit switch turns off and have a debounce that says the switch must be off for xx amount of time before counting the signal again. hope that made sense, if not let me know

DanielCamacho · Jul 20, 2005

Sample...

Try this...

TConnolly · Jul 20, 2005

Daniel, your example will upcount on the first scan.

I recommed this approach.

Its simpler and it functions with the on transition, as opposed the off transition, of the switch.

Regards.

Unregistered · Jul 20, 2005

or you could use a photobeam proximy switch, problem solved

DanielCamacho · Jul 20, 2005

I stand corrected....

Unregistered said:
or you could use a photobeam proximy switch, problem solved

BTW... this solution costs $$$$ programming is only a few minutes of time...

Mickey · Jul 20, 2005

What input module do you have. Some have build-in filtering to handle this effect.( Debounce filter)

Rupic · Jul 20, 2005

Entrelec Schiele Ps 200

Some Body Know This Plc?? What You Say Me About?

Dexstar · Jul 22, 2005

I have a plc 5/40 with a 1771IAD input card

Mickey · Jul 22, 2005

look here
http://literature.rockwellautomation.com/idc/groups/public/documents/webassets/browse_results.hcst?lineTitle=1771%20Universal%20I%2fO&familyTitle=Chassis%20Based%20I%2fO&categoryTitle=I%2fO&xLanguage=EN%20-%20English&CategoryId=0014&FamilyId=0104&PageNumber=2&StartRow=26&EndRow=50&SortField=xCatalog_Numbers&SortOrder=Asc&passedLangVal=EN%20-%20English

or

bioplc · Aug 9, 2005

Alaric,

Do you this your logic will work with delay time? Can u please tell me how it counts after a delay?

regards

bioplc · Aug 9, 2005

Sorry..

typo

do you think (instead of do you this)

thanks

russrmartin · Aug 10, 2005

I know the question was to try to solve the problem with programming, but it really seems to me that any switch that goes made and rattles into an on state after the part passes either is worn out, or needs tension adjusted, etc. I've seen millions of limit switches, as most of you have, and I wouldn't consider using a single one that when the actuator is releases, bounces around enough to change states. I suggest you look at the switch, I would think it's either worn out, or needs adjustment.

Russ

PLC 5 Problem....need help or guidance

Dexstar

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