Stability and Precision Issues with Data Acquirer "USB-2404-ui" and Load Cell "Utilcell model 620

[Otman]

Hello everyone!

I'm working on a project involving the data acquirer "USB-2404-ui" and the load cell "Utilcell model 620". When I connect the DAQ device to the "Instacal" software, I can choose the ADC Timing mode, which allows me to set the data acquisition speed. I've noticed that when I select "High Speed," the values I obtain during testing are very unstable and not very precise.

To improve stability and precision, I have tried reducing the data acquisition speed by using options such as "High Resolution," "Best 50 Hz Rejection," and "Best 60 Hz Rejection." While this does lead to more stable and precise results, I encounter an issue when trying to open the data in Matlab. Matlab displays an error due to the low data acquisition frequency, and unfortunately, I am unable to modify this setting directly from Matlab.

Additionally, the load cell I'm using has six cables, where two of them are meant to stabilize the current in longer cables. I attempted connecting these additional cables in the same slot as the current input and output cables, as my DAQ device lacks extra slots for this type of cable. However, this solution did not improve result stability.

I would greatly appreciate any advice or suggestions on resolving this issue and achieving stable and precise results in Matlab, despite adjusting the data acquisition speed in "Instacal." Thank you all for your help!

[Fausto]

Hello @Otman.

The Utilcell model 620 datasheet does indicate to connect the '+ SENSE' line with the '+ IN' line and the '- SENSE' line with the '- IN' line, as you stated, since MCC's USB-2404-UI does not support the sense lines.  

https://www.utilcell.es/wp-content/uploads/2016/07/En-De_DS_M620_Utilcell.pdf

 

Also, the Utilcell datasheet indicates that a nominal input voltage of 10 V is required, but the excitation voltage output from the USB-2404-UI is only 2.7 V for a 350 Ohm full-bridge.  https://www.mccdaq.com/pdfs/manuals/USB-2404-UI.pdf

Have you tried using an external voltage source for the load cell's '+ IN' and '- IN' lines?

Regards,

Fausto

[Otman]

12 hours ago, Fausto said:

Hello @Otman.

The Utilcell model 620 datasheet does indicate to connect the '+ SENSE' line with the '+ IN' line and the '- SENSE' line with the '- IN' line, as you stated, since MCC's USB-2404-UI does not support the sense lines.  

https://www.utilcell.es/wp-content/uploads/2016/07/En-De_DS_M620_Utilcell.pdf

 

Also, the Utilcell datasheet indicates that a nominal input voltage of 10 V is required, but the excitation voltage output from the USB-2404-UI is only 2.7 V for a 350 Ohm full-bridge.  https://www.mccdaq.com/pdfs/manuals/USB-2404-UI.pdf

Have you tried using an external voltage source for the load cell's '+ IN' and '- IN' lines?

Regards,

Fausto

Will using an external voltage source solve the problem of stable results?

[Fausto]

@Otman,

The load cell requires that voltage input level to function properly.  Please reach out to Utilcell for assistance regarding an explanation of their device's voltage requirements and how to connect an appropriate external power supply.