BRX Scale system

[PLCwannabe]

I'm looking at a project for automating a cement batching plant. I'm hoping somebody can recommend a good commercial grade weigh bar/ scale system, that can communicate with Brx Plcs. Thanks in advance for any recommendations.

[brucek]

Mettler Toledo has some nice little scale heads that are din rail mount that give analog out. Part # IND 110. just figure out the load cells you need and summing board. Can also use a bigger scale head that usually have analog or serial out as an option as well.

Rice Lake, Cardinal are other brands we use for scale heads and load cells.

[pbw]

I've used Rice Lake SCT-1100 Module with good success.
It's Din Rail Mountable.

[PLCwannabe]

So I'm looking to scale 2 hoppers separately, 4 weigh bars per hopper,(50000 lbs per hopper) preferably a junction box right on each hopper to connect the cells, then use comm cable to building, modbus via BRX/HMI combo to display the weights. Does this sound doable? Or do I still need a scale head or (summing board? ) between the plc and junction box to process the weights?

[brucek]

Everything we do with loadcells if more then 1 use a summing board. Most loadcells we use are 30mv/v and have 10vdc excitation so your analog card won't be getting much of a signal just from the cells. I'd use a signal conditioner if you can find 1 for mv to 0-10 or 4-20 or a scale head.

Not sure what your budget is but we do bins above 1 weigh hopper and put the material into the weigh hopper 1 at a time so 3000 lbs of bin1 then 5000 bin2 so total on scale is 8000lbs.

[Bolt]

I prefer serial (or modbus) vs analog in a situation such as this. but it's all in how accurate you need/want it to be.  The serial will let you zero the scale, and get a more exact reading without any analog "noise".  I'd go with something from the Rice Lake DIN rail mounted SCT-10 or -20 families.

[PLCwannabe]

I'm thinking serial as well. Does that then mean I have to get a scale head to communicate with the plc? I had envisioned connecting the load cells to a junction box/controller right at the hopper, and then just running DC power and serial cable from the building and plc cabinet.

[Bolt]

Yes that would work, the SCT would effectively be your summing board, scale head and serial convertor all in one.