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By gwiskur
#194208
My OpenScale SEN-13261 has been reading undisturbed since about 5:20 pm yesterday with a 100 lb load; however, I'm occasionally getting outlier readings (+/- ~2700 lbs). Refer to the plots below; Is this noise from the HX711 ADC, or a firmware bug? Plotted values are the max/avg/min of the last 50 readings from OpenScale serial port.

load cell #1 plot:
https://drive.google.com/file/d/0BwybDK ... sp=sharing
(on board) temperature #1 plot:
https://drive.google.com/file/d/0BwybDK ... sp=sharing

Steps I've taken to resolve the issue:
  • Increase the time between OpenScale readings from 100 ms to 150 ms
  • Flash the latest firmware from Github to OpenScale
  • Re-read OpenScale documentation & search google
Any ideas about why the outliers are happening, or what to do about it?
Is anyone else seeing this same issue?

Thanks in advance!
By D_Heidner
#194993
I've seen the glitches when just using the HX711. If you look at the raw data - is the data swinging all the way to one rail or the other? Sometimes I think the problem may be with the load cell connections or a problem on the loadcell. I have a scale built up using four full bridge loadcells and replacing the HX711 module (not openscale) did not fix the problem - it appeared to be load cell related.

That being said - hows the shielding around the openscale board - it may be indeed picking up noise itself.

But I would suggest looking at those outliers and see if its related to swinging rail to rail.

If there is a rail to rail swing, the problem isn't a bad load cell, and you've shielded the box - then I'd be tempted to look at the power supply for the board itself and see if the the 5V excitation supply on the openscale is noisy. That had been a problem on some of the knock off HX711 amplfier boards.

It's also possible you've simply got a bad board. (not likely).