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I'm a homebrewer. I use 5, 4 legged 200 liter tanks to ferment the beer.

I would love to be able to weigh the tanks and have the signal on my PLC to see how much I have in the tanks.

Each tank weighs 40kg and if it's totally packed with beer, it weighs 250kg, which means that one leg carries a maximum of 62,5kg.

I'd like to use these very cheap load cells. It is said in the documentation that if I use two I can weigh 100kg, which is enough per leg, so I would need 8 load cells per tank.

But how do I connect the load cells, and how do I get the signal up to 5 - 10 volt for the PLC?

The wires from each leg will go to a box mounted on the tank. The box shall contain the electronics needed to join signals from the 8 load cells and send a single the 5 - 10 volt signal to the analog input port on the PLC per tank.

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marked as duplicate by PeterJ, Daniel Grillo, user17592, Matt Young, placeholder Oct 2 '14 at 13:49

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    \$\begingroup\$ I can help, but it will cost you a beer :^) Nice link above. I think you'll want to use an instrument amp. You'll have to divide the load on each leg so it's shared ~equally with each load cell. Given that each cell will need it's own amp and such I wonder if 4 100kg load cells might be cheaper. Or as long as the tank is approximately balanced just weight one leg and multiply by four. \$\endgroup\$ – George Herold Oct 1 '14 at 13:55
  • \$\begingroup\$ electronics.stackexchange.com/q/102164/30711 gets you to 4 load cells. You could put them in the circuit as pairs in parallel and get the same results. It is likely that the load is not even on the four feet. One could be out of adjustment with the others, and have no load, putting its load on one or more of the other three. \$\endgroup\$ – Dave X Nov 9 '15 at 20:53

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