Industrial Truck Scales - Universal Data Protocal?

Joms

I am attempting to interface to several large scales.· I have been doing some research on the internet but finding conflicting information.

Is there some type of protocal that is normally universal between large scales.· Maybe the same data that is output to the large score-board type displays?· What I am idealing trying to do is design a circuit that can be used on many different scale controllers and input the displayed weight to a prop.

Is there anything universal in that world?· Has this been talked about and I just can't find it?· Mr. Sisk have any ideas, this seems right up your line of designs?

Thanks in advance...

stamptrol

Hi,

The data string is similar among the scale manufacturers but certainly not "standard". I've used Toledo, Western, Rice Lake successfully with BS2. The Scoreboards are usually able to be switched from one manufacturer's string to another.

The Stamps can listen to most any that can be set to 4800, although the BS2sx works nicely at 9600. Using a Prop you should have no issues.

As for listening to several different pieces of equipment, you could play around with capturing the data string then parsing it within the Stamp/Prop to figure out which scale it is then process the string accordingly.

What I have done in several cases is just allocate a pin to each specific scale indicator and hook the scale to the right pin (usually through a 10K resistor).

Let me know if I can answer any specific questions.

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Tom Sisk

http://www.siskconsult.com
·

Joms

GREAT! What I am actually trying to do in this specific project is hook two Jag Xtreme (made by Mettler Tolodo) controllers to a prop. I will then use that data to do a few calculations and log the data.

The reason I ask about the different types is because I would like to use this product on a few other designs also. Do you know if the scoreboards normally use RS422? Can I just split the data at the back of the controller where it goes to the scoreboard, then take that data to a prop? If it is RS422 I have used a 75ALS176P IC many times before to switch the RS422 to 232 that the prop can use.

Do you know the common baud rate that most systems use?

Thanks Tom.... I kinda thought you would be the one to know all about this stuff...


EDIT:

Would you or anyone else happen to have any sample code for the prop?· If you don't for the prop would you happen to have anything for the stamp that I could see?··· I assume the string just keeps getting sent out of the controller continually and you just programmed the stamp to wait until it seen the first charactor?

Sorry for all the questions but I am really excited about getting this working.· Thanks again in advance for all your help...

Post Edited (Joms) : 7/15/2009 10:54:22 PM GMT

stamptrol

·Hi,

·· I've attached an older version of my BS2 scale automation program. Overall it does a bunch of different things to fully automate the weighing process, but down about line 282, in the Subroutines you'll see how the string capture works. I think this one was using the Toledo string. You can see where we were testing for zero depending whether the leading zeros were surppressed or not.

·· It has a lot of code REM'd out because the program was used with a whole bunch of different indicators and each site might need different ways of communicating with the equipment. This one talked/listened to the indicator, the road loops and photocells, traffic lights and the transaction computer.

· Splitting the serial string for the scoreboard will work as long as the extra load doesn't load the port too much. The 75176 is a good chip to use, remembering that the serial side is at TTL levels. Overall, the scoreboards are not too hard to deal with because they only watch for the digit part of the string and many are configurable. Many of them do accept 422/485 as well as 232, but different manufacturers have different ideas.

· Our preferred method was to set the indicator to "Continuous Output" so the data would be coming every 2 seconds or so. The Stamp would then be able to use the SERIN with the Wait modifier. When we saw <002> go past, that would trigger the string grab very reliably.

·· If you can't use Continuous output for some reason, the Stamp will have to trigger the serial output each time it needs a new string.

·· Also note, this program can switch among three baud rates by watching an input pin.

· Cheers,

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Tom Sisk

http://www.siskconsult.com


Post Edited (stamptrol) : 7/16/2009 12:28:33 PM GMT