Weighing Scales to PLC

Grendizer · May 4, 2013

Hey All,

I want a weighing scales, range = 0.1g to 300g, that can be linked to a PLC and be able to read the weight from the PLC. I don' want big industrial scales, just small once, for prototype projects. Question is: does anybody knows a website/store/etc. where I can buy them from?

Thank you people,

G

ndzied1 · May 4, 2013

Try Cardinal Scale. They have the industrial stuff but they also have some simple ones.

We integrated one with a Phoenix Contact ILC-130 PLC once. It was a little tricky parse the ASCII string from the scale but once it was written it worked well.

Grendizer · May 4, 2013

Thanks for the reply, I will do the search now.

iant · May 4, 2013

IF you have a scale with an (Usually Optional)analogue output, you will be able to input that directly into a PLC with an Analogue input.
Then simply scale that input.

Grendizer · May 5, 2013

Well, the thing is I don't have any scales. I am looking for a place to buy such scales. Like you said, if i can get small sensitive once, I might be able to "hack" them and get the signal i want to the PLC.

Grendizer · May 5, 2013

I want the proper hardware

Lancie1 · May 5, 2013

Well, the thing is I don't have any scales. I am looking for a place to buy such scales.

If you have more time than money, you can buy 3 or 4 load cells (strain gages), and a strain gage controller similar to this Omega DP25B, and make your own weighing scales. The DP25B has an analog output option that can be sent to a PLC analog input. I have used the D25S (discontinued) to weigh process material bins when the customer wanted a cheap method. Omega also has other more accurate but more expensive strain gage controllers.

http://www.omega.com/ppt/pptsc.asp?ref=DP25B_E&Nav=a03

The scale output range will depend on the specific load cells that you buy. You can get load cells with ranges from grams up to thousands of pounds or kilograms.

brstilson · May 6, 2013

A company called Helm makes load cell modules for the various AB platforms:

http://www.helminstrument.com/allenbradley/

100 microsecond update time they're claiming, which is pretty impressive (other modules I've seen had 1-2 SECOND update times).

Haven't used them, ever. But it seems this way you could just get a scale base without the instrument.

JesperMP · May 6, 2013

It is not clear to me if you are after a weigh scale (albeit low-cost), or just load-cells.

blueyedpeter · May 6, 2013

Gedge scaling systems but the loader might be a volumetric screw device , but cant quite remember the brand though they were used for measuring fine adds to a batching system 3000 series scale or 3600 series they proved to be rather reliable in Extremes of conditions , the screw device was only about 20mm in diameter it only had to weigh about 500 grams up to about 1.2kg per cycle

blueyedpeter · May 6, 2013

Just to clear up one thing the scale bed had three load cells under the table the screw device and hopper all sat on top of the bed the scale would be tared to only read the continence of the hopper so it was more like a subtraction scaling process and not an addition process the product would be screwed out into the process on the fly to better distribute the fine adds through the batch

blueyedpeter · May 6, 2013

For the prototype projects some scaling company's can sell a load cell simulator which allows you to not build the load device and concentrate on the plc or the controller at any point you will need a signal for a given load and a way of getting it to the plc now in the real world span and range and off set problems occur and the scale unit might be the best way to contain these calibration issues but the simulator allows simplicity for the load and subsequent signal cheers and good luck

gbeaker · May 7, 2013

Buy this http://www.ricelake.com/products/be.../benchmark-series-light-capacity/benchmark-sl

or this (and make your own base)

http://www.ricelake.com/products/lo...ke-single-points/rl1010-single-point-aluminum

and this

http://www.ricelake.com/products/in...al-conditioning-transmitter-indicators/sct-10

Together you will have a scale with an analog output you connect directly to the plc. This is the cheapest option. For ease of calibration it is better to use a scale indicator like this http://www.ricelake.com/products/in...ice-lake/iq-plus-355-digital-weight-indicator with an analog output option card installed.

Lancie1 · May 7, 2013

This is the cheapest option.

It is not cheaper compared to buying the Omega DP25B-E-230-A ($330) and 3 load cells of whatever size needed. The Omega DP25B runs off 120-230 volts, no power supply needed, and has built-in 5, 10, 12, and 24 VDC excitation voltages for your load cells. Of course the Omega unit will connect directly to a 4-20 mA analog input on a PLC. It also has built-in functions such as Tare, callibrate, and reset, using front-panel buttons, or PLC control using inputs to the terminal blocks.

gbeaker · May 7, 2013

So your converter is $70 cheaper than the one I linked. My solution uses one load cell instead of 3. Its silly to use 3 or 4 load cells for an application with a 300g capacity. I was just linking to a sample converter to show him the concept. I was only suggesting loads cells + a converter is cheaper than buying a premade scale with an analog output option.

Weighing Scales to PLC

Grendizer

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ndzied1

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Grendizer

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iant

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Grendizer

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Grendizer

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Lancie1

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brstilson

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JesperMP

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blueyedpeter

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blueyedpeter

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blueyedpeter

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gbeaker

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Lancie1

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gbeaker

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