Need to process input from digital scale and output digital readings

[cox018]

I have some questions that will hopefully basic to you guys, but this field isn't my forte, so any help would be appreciated.

The project is this: to take the digital output (reading) from a normal floor scale, and process it to subtract a specific number taking the result and converting it into ounces. I need to output that number to one digital display, and then on another digital display, I need to take the number in ounces and divide it by 12.

Yeah, so I'm not exactly sure how to construct all this, or even if I can do it on my own. If I'm unclear on the specs of the project, don't hesitate to email me. (acox@ampitech.com). Any help would be appreciated!!!

 

[IRstuff]

Your statement's a little confusing:

to take the digital output (reading) from a normal floor scale, and process it to subtract a specific number taking the result and converting it into ounces. I need to output that number to one digital display, and then on another digital display, I need to take the number in ounces and divide it by 12.

If you're converting to ounces from pounds, you need to multiply by 16. Your division by 12 sounds like you're converting to pounds, except that it shuold be 16 and not 12. But, then again, you started with pounds to begin with?


As for the mechanization, you could probably do this with either a PC or a Stamp processor running Basic driving a couple of smart displays.

TTFN

 

[skills]

Of course, if we're weighing gold or platinum then dividing by 12 does yield pounds!!

 

[cox018]

It's actually two seperate outputs. One is the conversion from pounds to ounces. The other is the total number of ounces, divided by 12. The project is to measure how much beer is left in a keg that is tapped, and display that number of ounces on a display. On the second display, it calculates the number of ounces left divided by 12 to display the number of 12 oz beers left in the keg before it needs to be refilled. Sorry for the confusion.

 

[IRstuff]

So are we talking a single weighing system attached to a PC? or some sort of handheld unit?

TTFN

 

[cox018]

The scale will not be attached to a pc. I need to take a normal floor scale that has a digital display and run that data as input in the process.

 

[Warpspeed]

This might actually be fairly difficult.

If it is a commercial scale it will probably use a strain gauge and amplifier driving a digital voltmeter meter chip. The problem is that the display, either LED or LCD is almost certainly going to be multiplexed.

You cannot just wire something to the display pins and get meaningful data out, because the digits are energized sequentially in a repeating pattern.

This is done to reduce the number of interconnections to the display, reduce power consumption if it is LED, and prevent burning the display if it is LCD.

Anything is possible, but it is not going to be a trivial design exercise.

 

[automatic2]

A 'normal' floor scale for domestic use will not be usable because the embedded controller will not have usefull outputs, other than it's own display. A commercial scale on the other hand will give you the ability to do what you need, or at least likely have a port that will respond to basic commands, including the output of wieght data. Head down to a few auctions or second hand food equip. brokers and you'll eventually find one for cheap.

When you say that you will not use a PC, I wonder what then will 'process' the scale input. A cheap old 286 for $5 will perform this and many other statistical processes that might be usefull. And that cheap commercial scale will very likely have a good 'ol RS232 port.

 

[Kido]

if you are talking about using the display off a set of scales to use as you data in then you will have to trace it back to before it gets multiplexed then take that load of data (most likley BCD) and put it through something like a pic chip to do your conversions then output this if possible in the bcd code and then use a multiplexed display.

or alternitavley you get rid of all the electronics in the thing that is digital then take the output voltage off the op amp and run that through an adc then that into the pic chip do what you need to do with it and then spit the data out to your displays, this could be done serialy to reduce the number of outputs needed, you just need one as it would be easy to change the output of the pic between ounces left and beers left just using a push button on one of your inputs, this reduses power consumption of the displays and reduces the amount of curcitry needed to get the outcome your after