Host Engineering Forum
General Category => Do-more CPUs and Do-more Designer Software => Topic started by: maciek on April 19, 2017, 09:04:29 PM
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what would i use to read a load cell that has 3mv/v output and 10v excitation
any suggestions
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Signal conditioner. ADC alone has two series. Get a 4-20ma output and wire it to the PLC.
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Signal conditioner. ADC alone has two series. Get a 4-20ma output and wire it to the PLC.
I like to get the programmable ones, that way I have access to everything I could ever need. (dont' forget the programmer!)
(https://i.imgur.com/H3ha4qe.png)
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thank you
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i looked at the specs of that signal conditioner and it doesn't say about millivolts per volt 3mv/v like what the load cell puts out
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No, it doesn't appear to be a load cell conditioner. The APD-4051 from API (https://api-usa.com/pdf/api/apd4051.pdf) is similar to what you want though it is incredibly difficult just to find a price. AutomationDirect spoils us.
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I am not sure what you are trying to do with a load cell, but it may be wise just to attach the load cell to a scale head and then read the weight from that. This may me necessary for working with scales that must be legal-for-trade. There are also these (http://www.futek.com/product.aspx?t=instrument&cat=aa&m=iaa200) or these (http://www.futek.com/product.aspx?stock=FSH03633) from Futek.
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i looked at the specs of that signal conditioner and it doesn't say about millivolts per volt 3mv/v like what the load cell puts out
"mv/v" is not a signal format, it's a hardware characteristic of the load cell. Feed it 10v, or whatever is within it's range, then take the 0-30mv full scale (or 0-[3 x excitation voltage]mv) and isolate/condition that with the signal conditioner to 0-10v or preferably 4-20ma.
Some thermocouple modules will even handle mv signals (such as from high current DC shunts, etc.) directly, but it's kind of hit and miss how well it works, so I'd stick with the signal conditioner. IIRC, you're doing this in a BRX, which at this time doesn't have any [local/native] thermocouple inputs anyway.
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I realize this is an old post but I found it by a search engine. So if it helps you can use something like this load cell amplifier https://loadcellsys.com/product/tle-load-cell-amplifier/ (https://loadcellsys.com/product/tle-load-cell-amplifier/) we sell a ton of these for people interfacing with a PLC. Simple and inexpensive. Typically less expensive than dedicated load cell input modules from other PLC manufacturers.