Comments on: Arduino and Load cell http://cerulean.dk/words The article and blog words of Christian Liljedahl Thu, 02 Sep 2010 23:26:57 +0200 http://wordpress.org/?v=2.8.6 hourly 1 By: chrlilje http://cerulean.dk/words/?page_id=42&cpage=1#comment-3614 chrlilje Thu, 02 Sep 2010 23:26:57 +0000 http://cerulean.dk/words/?page_id=42#comment-3614 Did you make your load cell yourself, using strain gauges? In that case, if you have a half-bridge configuration, you will get drifting values due to temperature changes. This can also be the case, if you are running long wires to your load cell, I think. I have always made my designs able to auto calibrate every now and then. Good luck! :-) Christian Did you make your load cell yourself, using strain gauges?

In that case, if you have a half-bridge configuration, you will get drifting values due to temperature changes.

This can also be the case, if you are running long wires to your load cell, I think.

I have always made my designs able to auto calibrate every now and then.

Good luck! :-)
Christian

]]> By: martin http://cerulean.dk/words/?page_id=42&cpage=1#comment-3605 martin Thu, 02 Sep 2010 11:29:37 +0000 http://cerulean.dk/words/?page_id=42#comment-3605 Thanks for the advice. I got the load cell to work properly finally. The problem was bad soldering. Right now I am running an arduino and processing visual graphing program to visualize deflections. My new problem is that the reading from the INA125P drifts. I cannot get a fixed value as a basis or zero line since it keeps on drifting. Any guess / tip regarding this? Thanks for the advice.
I got the load cell to work properly finally.
The problem was bad soldering.
Right now I am running an arduino and processing visual graphing program to visualize deflections.
My new problem is that the reading from the INA125P drifts.
I cannot get a fixed value as a basis or zero line since it keeps on drifting.
Any guess / tip regarding this?

]]> By: chrlilje http://cerulean.dk/words/?page_id=42&cpage=1#comment-3575 chrlilje Tue, 31 Aug 2010 16:12:56 +0000 http://cerulean.dk/words/?page_id=42#comment-3575 Hi vito Sorry for not posting the code yet. It was developed on an old computer, and I havn't dug the code up from it yet. I hope you can make your deadline - It is quite simple - Read an analog value, and change it to a corresponding kilogram value. It is linear, so its a basic linear function. kind regards Christian Hi vito

Sorry for not posting the code yet. It was developed on an old computer, and I havn’t dug the code up from it yet.
I hope you can make your deadline – It is quite simple – Read an analog value, and change it to a corresponding kilogram value. It is linear, so its a basic linear function.

kind regards
Christian

]]> By: chrlilje http://cerulean.dk/words/?page_id=42&cpage=1#comment-3574 chrlilje Tue, 31 Aug 2010 16:11:05 +0000 http://cerulean.dk/words/?page_id=42#comment-3574 Hi - Regarding sensitivity, then I could get about 0.1 kg sensitivity from a 1700 kilo load cell. This I did using about 6000 times of amplification with the resistor. If you don't see any deflection, then it is off somehow. It is very visible, when it is visible. Did you build your load cell yourself? Sometime the cell is skewd, and you need to add a resistor to correct it. You should be able to see a milivolt change on a normal multimeter, even without the amplification of the INA125. My best bet is, that you have connected the wires wrongly. The color codes are completely different from manufacturer to manufacturer. Hope you get it working! kind regards C Hi – Regarding sensitivity, then I could get about 0.1 kg sensitivity from a 1700 kilo load cell.
This I did using about 6000 times of amplification with the resistor.

If you don’t see any deflection, then it is off somehow. It is very visible, when it is visible.

Did you build your load cell yourself? Sometime the cell is skewd, and you need to add a resistor to correct it.

You should be able to see a milivolt change on a normal multimeter, even without the amplification of the INA125. My best bet is, that you have connected the wires wrongly. The color codes are completely different from manufacturer to manufacturer.

Hope you get it working!
kind regards
C

]]> By: martin http://cerulean.dk/words/?page_id=42&cpage=1#comment-3544 martin Mon, 30 Aug 2010 07:26:04 +0000 http://cerulean.dk/words/?page_id=42#comment-3544 Hi, Good day. I am trying to use your setup with the load cell for my thrust stand setup. My load cell is a 40 kg one with 5 pins: red, black, black, green and white. I connected the pins while coupling the two black ones similar to your circuit. Apparently, I have not seen much deflection from the INA125P Vout reading. Can you give me a typical reading from your setup. I have been literally standing on it while the load cell is on the edge of a wooden table and I can't see deflections. I hope you can help me. Thanks, Martin Hi,

Good day.
I am trying to use your setup with the load cell for my thrust stand setup.
My load cell is a 40 kg one with 5 pins: red, black, black, green and white.
I connected the pins while coupling the two black ones similar to your circuit.
Apparently, I have not seen much deflection from the INA125P Vout reading.
Can you give me a typical reading from your setup.
I have been literally standing on it while the load cell is on the edge of a wooden table and I can’t see deflections.
I hope you can help me.

Thanks,

Martin

]]> By: vito http://cerulean.dk/words/?page_id=42&cpage=1#comment-3391 vito Tue, 24 Aug 2010 12:46:02 +0000 http://cerulean.dk/words/?page_id=42#comment-3391 Hy I am working on the exact same project in scholl and would love it if you`d post the code... I tryed doing some work on the code, but I do not have an arduino kit yet, and my deadline is coming up... Would be very grateful for the code. thank you Hy I am working on the exact same project in scholl and would love it if you`d post the code…
I tryed doing some work on the code, but I do not have an arduino kit yet, and my deadline is coming up…
Would be very grateful for the code.

thank you

]]> By: barry http://cerulean.dk/words/?page_id=42&cpage=1#comment-741 barry Wed, 31 Mar 2010 00:02:25 +0000 http://cerulean.dk/words/?page_id=42#comment-741 ok, thats great - thanks for your help - will let you know how i go ! ok, thats great – thanks for your help – will let you know how i go !

]]> By: chrlilje http://cerulean.dk/words/?page_id=42&cpage=1#comment-739 chrlilje Tue, 30 Mar 2010 21:54:24 +0000 http://cerulean.dk/words/?page_id=42#comment-739 Hi Barry The way to convert your analog data to kilos is by calibrating your load cell. The great thing about load cells is, that they behave linear. So you only need two data-pairs to do the rest. I havn't converted my data to actual weight. But do something like this: Lets say you have a 10 Kg load cell Put 1 kilo on and read the analog value Put 2 kilo on and read the new analog value A quick way around converting your values is by using the map-function in Arduino (http://www.arduino.cc/en/Reference/Map) If I at some point make some actual kilo-conversion-code, I will surely post it. :-) good luck! C Hi Barry
The way to convert your analog data to kilos is by calibrating your load cell.
The great thing about load cells is, that they behave linear. So you only need two data-pairs to do the rest.
I havn’t converted my data to actual weight.

But do something like this:
Lets say you have a 10 Kg load cell
Put 1 kilo on and read the analog value
Put 2 kilo on and read the new analog value

A quick way around converting your values is by using the map-function in Arduino (http://www.arduino.cc/en/Reference/Map)

If I at some point make some actual kilo-conversion-code, I will surely post it. :-)

good luck!
C

]]> By: barry http://cerulean.dk/words/?page_id=42&cpage=1#comment-715 barry Mon, 29 Mar 2010 02:51:45 +0000 http://cerulean.dk/words/?page_id=42#comment-715 Hi, sorry, been a while - i had to spend some time on another project. anyway, the problem i have is mapping the reading from analog pin 0 to a human readable format - in kilograms and grams ... if you are able to mail me your code (if you created the code with a conversion to kg) that'd be erally useful ! many thanks Hi,
sorry, been a while – i had to spend some time on another project. anyway, the problem i have is mapping the reading from analog pin 0 to a human readable format – in kilograms and grams …
if you are able to mail me your code (if you created the code with a conversion to kg) that’d be erally useful !
many thanks

]]> By: chrlilje http://cerulean.dk/words/?page_id=42&cpage=1#comment-216 chrlilje Sun, 10 Jan 2010 23:48:19 +0000 http://cerulean.dk/words/?page_id=42#comment-216 Hi Barry What exactly are the problem with your code? Since its all about sensing at the analog input pin, you should take a voltmeter, and test what you get there. Then adjust accordingly. I can post my code here when I get to it tomorrow. Or, post your code to me - I may be able to deduct the problem from your code :-) yt Christian Hi Barry
What exactly are the problem with your code?

Since its all about sensing at the analog input pin, you should take a voltmeter, and test what you get there. Then adjust accordingly.

I can post my code here when I get to it tomorrow. Or, post your code to me – I may be able to deduct the problem from your code :-)
yt
Christian

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