Hi to everyone:
I want to do my firs proyect with an arduino but i have a question before i start. For my work i have to weigh some food additives in a precision scale so i want to make something that weigh for itself with arduino and my question is: Can i, somehow, plug my scale to the arduino so it can input the infotmation of the additive i am weighting? My scale is a HZT from PREC.
Since you have your scale, how about letting us see the documentation so we can suggest and answer. No fair keeping all that stuff to yourself!
How are you planning to input information into Arduino , and then what will you do with it ?
It might be better on a PC , unless it’s something simple such as press a button to select ingredient and a screen tells you what weight to put in . But then it doesn’t need to talk to the scale ? … yep need that scale info and what commands are possible with it
If you make such a machine , they won’t need you …..
I think i can find it somewhere, i just need to look up for it. If i manage to find it i will post that info!
I am thinking on the second option you gave, you select the weight and with a servo that open a bowl it will drop the ingridient on a jar. It need to talk with the scale because, for example, if you select 5 grams the servo open till the scale shows 5 grams on the scale and then it close the bowl. I know that i can do the mechanism but i dont know if i can conect the scale to the arduino.
They will need me because that is just 1 of my many tasks, i want to automate that part so i can focus on other things.
Excuse my english =)
No, that won't work because you are weighing what is already in the jar, not including what is in flight while the bowl is open.
Can you weigh what’s left in the bowl instead?
I know, but my english is not good enough to descrive in detail what i wanna do. Actually if you select 5 grams the servo will stop at 4 grams and open and close for intervals of time till it reaches close to the 5gr.
I suppose i can but i still dont know if i can connect the arduino to the scale
You could consider buying a cheaper scale and doing your own signal conditioning with an accurate ADC breakout with a serial connection and calibrating it with your expensive scale.
But non of the cheaper scales have a precision of 2 decimals, thats the main problem in changingthe scale and thats why i wanna know if i can connect the arduino to a comercial scale
That’s why I suggested you could calibrate the cheaper one with the accurate one.
The time to think about connection to a controller was before you purchased the scale.
Cheaper scales may not be able to be calibrated to a high degree due temperature drift , measurement performance off centre of the weighing pan etc .
This is not an easy project for the beginner , building the hardware , which needs to be food safe will ( stainless steel ?) be expensive for starters . powders can easily clog up valves and so on , you might need screw type mixing , vibration etc etc.
Normally done by mixing large quantities ( which is easier ) then weighing out mix for each product .
Cheaper scales are not an option, even if i calibrate with an expensive on the cheaper one will not have the precision enought, if it were that simple all labs with a scale with a miligram resolution will do that instead of waisting $2000 on a scale
Yes, its not an easy proyect if i just start with arduino but i know i can do it and i am not worried about the hardwere, I can handle it, the softwere part is the problem 
If it's this one:
it has an RS232 output. Easy to interface to Arduino, or PC.
The answer is yes, you can connect Arduino to some commercial one. The problem is, the one you selected is apparently not one of the ones.
Since you are not worried about the hardware and can handle it, I’d say the next step is to modify your existing scale to include an interface to a controller. Once you’ve handled that, you can worry about the software part.
But you need the hardware in place before you can control it with the Arduino , so that’s your initial problem - you can’t write the software first
Sorry, when I said calibrate I meant also condition to minimize error due to temperature drift, etc. Load cells tend to drift in a predictable direction and it’s possible that OP could design an interface to the load cell that had both the precision needed and a computer interface.
In the lab we have 2 scales and one of the scales es the one you find. I was hopping i can use the other one because its faster but if you say that i can conect an rs232 to the arduino thats a good start! TY