Load cell goes full range without loading after calibration

[hygeia44]

Hi there,

I did the calibration for the load cell  GSO-500 using MAX & NI9237, analog input/strain calibration.  I am not sure if I put the parameters correctly. The shunt resistance is 100k  and R3 for the full bridge.

However, After I did the calibration, the reading of load cell(500g ) just oscillated between the max and min limits ( actually reached both limits) without any loading. Could anybody can help with that?

[aNIta B]

Hi Hygeia,

         Could you give us a little more information?  How are you connecting your load cell? Can you please give more details on your setup and the steps that you've taken in software as well?  Thanks in advance!

[hygeia44]

Hi aNlta,

The hardware are NI9237, Chasis NI cNAQ-9172.

The load cell has four wires: Green(+signal)  connected to Pin 2(AI+),  white(Signal ) to 3(AI-), Red (+excitation)  to 6(EX+),  Black (Excitation) to 7(EX-).

I use the MAX, Create task-- Acquire signal--Analog input--Strain--Select channel ai0--strain calibration--enable offset nulling and shunt calibration-value 100K and location R3. Then the reported error is 515.37% and 603.25% after shunt calibration.

Then I run the example VI load_cell_null_off_shuntcal.vi    and give the rang of 500 grams.  The reading is way out of the rang and goes to 10323 and goes down to -2000 without any loading. We do have a load stem on top of the load cell. Does that affect the reading so much ?

Appreciate your help!

Melody
                                                                                            
                                                                                             

[aNIta B]

Hi Hygeia,

           I'm wondering if you try to create a Custom Voltage with Excitation Task if you see any different results?  As well, have you checked out THIS page of the operation instructions that discusses connecting to the 9237.  Is there another strain gauge you could try?  As well, can you explain what your load stem does?  Thanks!