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Loadcells and Variable Linearization

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I am very new to PLCs, but I have learned a lot during the past few weeks and I finally managed to program the routine I need except for the loadcells.

I have read and re-read every single help topic and example available regarding loadcells. I have also consulted the new and old forums but I'm still stucked with this issue.

I can place the loadcell calibration FB along with the scan, tare, zero and write to eeprom commands. I do get readings but unfortunately I'm afraid those readings are not being converted to actual grams.

For some reason the read zero is not working for me. Also I have no idea on how to linearize the variable I'm using on the HMI.

I know the Y range is 0-1000 grams but I have no clue regarding what should be set on the X range.

The loadcells are 2.2 lbs made by FUTEK model LRF400. they have an RO of 2mV/V nom. and a zero balance of + - 3% of the RO.

I'm not sure if I need to set the gain and offset for the LC, the reading between +SG and -SG is 0.1mV AC.

I would really appreciate your help in order to finish this project.

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You do not need to enter the X range yourself. The X range value comes from the LC.

In order to calibrate the LC please do the following:

Prepare an object whose weight you know for sure.

Store that weight in an ML, put that object on the LC and activate the Calibrate Point function with that ML.

Do the same with no weight and another ML which holds 0.

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Ok so this was much more simple than I thought. Thank you very much.

I have one more question for you.

How do I get the PLC to capture a weight value and store it on a table every cycle so that it can generate a report were I can read the weight change that occurred on each cycle?

Exporting it to excel would be great but I just need to be able to print out a report on whatever format.


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The loadcell works great, but I need to keep it from oscillating so much when it comes to the smaller readings. I set the scale to 000.0000 and rounded the last cero to 10. Is there something else I can do so that I can get a stable reading to 000.000?

I'm measuring water drops so its a bit critical to be able to have a stable reading at this resolution.

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