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Dear Fourm Members,
I want to aquire Data from 6 Load cells, logg this data into computer and controle some valves based on data measurements. I am new to this fourm and hope that any expert could guide me through best process to get my goal.
Thanks
A major issue here is reading the load cells. The load cells probably use strain gages in a Whetstone bridge arrangement. Signal conditioning will be required to amplify the strain gage output to a range that can be read by a micro's ADC inputs. Once the signals are amplified, reading the load will be straight forward.
First things first, can you supply data sheet links to the load cells. It sounds like you have an industrial design task, your cells may already have conditioned outputs. If this is the case, your design task is easy, you'll just need to read the outputs (digital or analog) into a pretty vanilla sort of micro circuit/logging cct. You may be able to get away with off the shelf equipment.
We'll need to know more to advise.
If you are reading them raw, you'll need a more elaborate cct as Jon has suggested. There the issue of reading Whetstone bridge which can be done by an 'instrumentation' amplifier (google this type) but also balancing, zeroing and temperature compensation. All doable....but we need more information to help.
Lastly we'll need some sort of idea of the accuracy and sample rate. High sample rates will require lots of memory (if you are storing it in a separate circuit) or a high bandwidth data connection to a computer to store it. High accuracy will require lots of attention to detail on the load cell construction, the wiring lengths, temperature sensors all the way to even how you solder the wires together. Low accuracy and you can simplify things a fair bit.
As a start, assuming a raw Whetstone bridge, I've used an AD8555 and AD623 instrumentation chips for low accuracy applications. Read the data sheets and app notes for these to get an idea on what your requirements are and post back once you've got a bit of a handle.
I have seen your Data logging project on the net.
**broken link removed**
This project is as same as it has made for Temparture sensors. The only diffirence is that the Load cell will be used for reading. and solinoid valves will be operated at heaters point. and the data should be added in log when the reading will at set point.
1- We want to weight the product at 6 Different places through load cells.
2- We want its Data into personal computer.
3- The process will be controlled automatically.
Dear LXT71CM I know the basic of Proton plus. I am not an Expert but biginer.
Dera Rgbphil yes it is an Industrial project but I am trying to experiment myself with the help of the people just like you. Please look at the above mentioned address project and advise me to go further. Because this project is very same as my with only diffrence of Weight and Temprature. According to my knowledge I can make a PCB from Schematic and could complete it with components. I have also PIC programmer available. I think the long distance from last load cell will be 100 Yard away from Circuit.
OK well the first place to start is to look at the app notes and data sheets for the chips I mentioned above. Then start looking at Whetstone bridges.
If you have the load cell data sheets you can put up a link for that would be a great help.
Basically an industrial load cell will probably have already the analog circuitry to read the Whetstone bridge inside it and will only need power and some sort of comms protocol to read it. If it doesn't then you'll need your own bridge amplifier...which will be in the data sheets and app notes.
Dear rgbphil,
Thanks for your intrest in my project. I have seen The specific part of the AD8555 and AD623 mentioned by you. these both are could be used for get and conditioned the signal from load cell. I have available load cell by Philips company and capicity 500Kg. Will AD8555 be connected to Directly Microcontroller or any ADC will be use before MCU. Please make a shematic of this project and then I will be able to move forward. Have your seen this link given my last post. I thinks it is easy after getting Analog signals from Load cells.
A person told me that he can designe this system with Fatek PLC. Fatek also has a load cell interface FBs 1Lc module. will you advise me to use PLC based setup or make my own. Do you know PLC programming ?
Thanks
Hi,
I'm happy to give advice on a forum, but designing a schematic and circuit is a little too much to ask for. You'll have to do that yourself or pay someone to do it.
If you can send a link to the specific Philips load cell part number and data sheet I can give it a look over and advise you on what sort of MCU or PLC interface you'll need. I've not heard of Fatek PLC 1LC modules before, but quickly googling it looks like you might have a raw Whetstone bridge in your load cells. If so, then I'd advise you as a beginner to take the PLC and pre-built PLC interface modules approach rather than design a specific circuit to save time and effort. Essentially these modules will do what the AD8555 or AD623 chips will do but also do the other conditioning you'll need without you needing to worry about it.
Dear rgbphill,
I was satisfied with Fatek PLC FBs32MA with FBs1Lc Module. But I could not program PLC and the professionals are very costly. They demands 1200$ only for programming PLC and software for PC or HMI. That is why I am wondering in search of an alternative. Look at this link www.fatek.com/Download Page/.../FBs_1LC/cat_1LC_enu.pdf
If you could write the program for PLC please let me know.
Thanks
Don't be disheartened, by all means do a little research by yourself and ask questions. Free advice is what the forums are for. Asking them also helps others learn.
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