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olkal / HX711_ADC

Arduino library for the HX711 24-bit ADC for weight scales
MIT License
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Drift Issue using 50 MT x 4 LoadCell (200 MT) #38

Closed sidikhanrei closed 4 years ago

sidikhanrei commented 4 years ago

Hi, I have big LoadCell with total 200 MT. Using this library on 5KG and 10 KG has no issue, But when connected to 200MT LoadCell, Reads of get data is unstable and fluctuated.

Do you have any idea to resolve this problem?

Thank you

olkal commented 4 years ago

No I don't have any idea. Could you provide a little more details like technical data for the load cell and amplitude of the fluctations.

sidikhanrei commented 4 years ago

Here is detail of the spesifications

  1. Type = ZSFL-A
  2. Plc = 0.7
  3. Sensitivity = 1.9993 mv/V
  4. Zero Output = 0.60% FS
  5. Input Resistance = 696.8 Ohm
  6. Output Resistance = 701.5 Ohm
  7. Safe Load Limit = 150% F.S
  8. Insulation Resistance = <= 5000 Micro Ohm
  9. Maximum Excitation = 20 V DC

or you can view at here BROCHURE

sidikhanrei commented 4 years ago

For more detail, the drift is about -40 KG to 60 KG from the original scale, and it's fluctuated wildingly.

When the load cells idle, I need to reset the Tare (if current weight showing more than 0).

Do I need to modify your library for my own situations? I need your sugestions to make this library more stable.

Thank you

olkal commented 4 years ago

The load cell data seems okay to me, don't see any reason there. However, the fluctations of -40kg to 60kg is at least 10 times as much as I would expect based on my (limited) experience on smaller load cells. Have you set the HX711 rate to 10SPS (pin 15 low)?
Could there be any electrical interference (nearby wires etc) that could have an effect on the signal/voltage between Load cell and HX711?

You could reduce noise by incrasing the value of SAMPLES in config.h, but I consider that to be last resort, if something is wrong it's better to find the root couse.

sidikhanrei commented 4 years ago

I use getSPS() return with 10.93. I dont know pin 15 Low mean, can you explain?

Oh one more, LoadCell is 5 wired (wire 5 is Shield), i just skip this shield or need to connect to hx711?

I will try increasing samples. Hope its solve.

olkal commented 4 years ago

If getSPS() return with 10.93 you have the 10SPS setting, thats good. Usually the shielding should be connected to the HX711 ground plane. Try it and see if there is any improvement.

olkal commented 4 years ago

The HX711 power supply also matters. You could try replacing it with som something else.

sidikhanrei commented 4 years ago

The HX711 power supply also matters. You could try replacing it with som something else.

Any reference how to do that?

olkal commented 4 years ago

I.e. if you are using a switched power supply now, try replacing it with a battery.

sidikhanrei commented 4 years ago

what the best baudRate for this library? I use 9600, but the examples use 57600

olkal commented 4 years ago

The baudrate is not important,, both 9600 and 57600 is fine.

sidikhanrei commented 4 years ago

I.e. if you are using a switched power supply now, try replacing it with a battery.

Its directly supply power to load cell or just hx711?

sidikhanrei commented 4 years ago

I.e. if you are using a switched power supply now, try replacing it with a battery.

Its directly supply power to load cell or just hx711?

If getSPS() return with 10.93 you have the 10SPS setting, thats good. Usually the shielding should be connected to the HX711 ground plane. Try it and see if there is any improvement.

How I can place the shield from load cell to hx711. The board just has E+, E-, A+, A-, B+, B-

Where to place the shield wire of loadcell?

olkal commented 4 years ago

The power supply you use for the HX711 and the micro controller. Voltage ripple from a (bad) switched power supply could disturb the adc conversions. If you are now using the same power supply that you used when testing the 10kg and 20kg load cells, it's probably fine and the problem something else.

The shielding from the load cell wire should be connected to ground on the HX711 module.

sidikhanrei commented 4 years ago

Today I'm trying using SAMPLES 32 and 64, it's more stable. But it's make zero position is not 0 (in randomly time), so I need to refresh the tare using tareNoDelay() when it's not zero.

Any solution, or it is normal?

olkal commented 4 years ago

No, it's not normal and you should not have to use 32 or 64 samples just to get it reasonable stable. So I think you have some kind of hardware problem, but I'm not sure what it is and I'm running out of ideas...

sidikhanrei commented 4 years ago

I have changed HX711 with another one, and it's look same. I've ordered new HX711 with Shielding. I'll try when its ready.

olkal commented 4 years ago

Okay

olkal commented 4 years ago

Closed, due to lack of activity.