need help to program a counter...

[junzan]

i have a conveyor system where output is being counted. Plc sends a pulse to a digital display counter(which can count only 1 count per pulse). There are times the product i'm running is in panel, say a panel of 2 or 3, what i want is that whenever i run that product i will change the preset counting to appropriate count pulse. My idea is to have 1 input; when I press&hold, it change to counter program mode where i can input using the same button how many pulse must output; after that press&hold again to save the data and the counter is now preset. How will I do that? Is it possible?

 

[Allen Nelson]

Physical counter

You might want to look at THIS OLD THREAD for ideas on pulsing to a mechanical counter.

A question regarding your proposed strategy:
If I'm understanding you correctly, you will have a single input button to change the logic so that the PLC will generate, for example, two pulses to the mechanical counter for every one pulse from a prox/photoeye sensor, to compensate for the fact that there are two units of product bundled together that the sensor cannot distinguish between.

My question: What kind of feedback will the operator have to know that the PLC is in "One" mode, "Two" mode or "Three" mode? Wouldn't a BCD thumbwheel be better?

 

[Tom Jenkins]

It can be done the way you suggest, but I wouldn't.

For the cost of the programming, operator training, occasional operator confusion, and wrong entry/lost production, you could very quickly justify the cost of a keypad or even small monchrome graphic operator interface. For what you want to accomplish the ladder logic program will take as long as configuring the inerface, and you can get what you need in an operator interface for well under $1,000 including software and cables. Check out EXOR and AutomationDirect.com

 

[JvdV]

I have to agree with Allen.

The cheapest way is to use a thumb wheel. The operator is not likely to make a mistake then. And when he makes a mistake it's easy to trace and correct.
Like you discribed, you will end up with a lot of code.

Putting in a Thumbwheel and the programm code for it wil take you 1/3 of the time to programme the same.
The most difficult part will be to make something for the operator to see what he is doing.
Most operators don't think like programmers. You have to make it fool prove. Otherwise you will end up explaining over and over again what they should do.

 

[spudman2]

If it's for production and you have operators and turn over. Make it idiot proof. Make it so the thumbwheel code gets attached to the shop order. Make it so its instituted as part of the SOP. W/O sounding brash, Make it so your mother in law can figure it out.

 

[junzan]

thanks for all your replies and suggestions. its true and also agree that what i want is not an idiot proof and no indication of what had been set. this solution comes out of my mind as this was the cheapest, it can be done without any cost just additional program which cost nothing. anyway thanks to all. i will try to figure out how it can be done.

 

[Allen Nelson]

... it can be done without any cost just additional program which cost nothing.

So you don't get paid to program? Your time is worthless? If it takes you 3 days to code a poor solution, this will save money over the cost of a $50 part and only 1 day of your time?

You need to work on your self-esteem. Until you value your contribution, no one else will. And they'll pay you accordingly.

 

[rogerhollingsworth]

I agree, Allen has given you some sound advice on both accounts.
1) Use a thumbwheel (you are not talking big bucks here.)
2) Your time & skills are worth something.

Roger