Comments: OpenScale Applications and Hookup Guide


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  • Member #1423550 / about 6 years ago / 2

    I have configured my openscale for fast, serial triggered readings: severed the connection on the board labeled "rate", disabled all printing characters except for the load (2 decimal places) and the units. Just to prove to myself that everything was working as it should, I pulled up the setup menu in a terminal, and started triggering measurements as fast as I could with the keyboard. I noticed that every 5 measurements or so, the value onscreen would display as about twice the actual load (I had ~50 lbs on a 1000 lb load cell powered with 5V). I know that operating at higher rates, increases the noise, but (if my math is right) the signal should be in the hundreds of microvolts i.e. noise < 1%. What could be causing the readings to vary by about a factor of 2?

  • -------------------- Tech Support Tips/Troubleshooting/Common Issues --------------------

    Issues With Calibration After Power Cycle

    If you calibrate the OpenScale, power cycle, and the open Scale resets to the default readings, try reuploading the default Arduino code from this branched repository [ ]. An engineer was able to resolve the issue by modifying the code [ ]. It will eventually be merged with the master after review. A customer that had this same issue and they were able to get it working as expected after reuploading the code.

  • Member #1531223 / about 3 years ago / 1

    how do we place the four load cells? where can we find a suitable pan to weigh the things? The sparkfun weighing scale (the big metal plate) is no where to be found online?

  • Member #1626826 / about 4 years ago / 1

    Having trouble opening "x" menu settings. We have installed Ardunio IDE, plugged Openscale in, and uploaded blink successfully, which means I believe we have a working connection. But the instructions state: 1) Wire your load cell to the board using the 4-pin connection (E+/-, A+/-) or the RJ45 connection. 2) Attach board to USB and open terminal at 9600bps 3) Press x to bring up settings menu

    I am opening the serial monitor, which I believe is the terminal mentioned in step 2, but this does not accept or return anything on entering "x".

    What am I doing wrong please? Thanks, Rob

  • Member #779822 / about 6 years ago / 1

    Please help with setup

    We connected the OpenScale board to pc using old Microsoft software called "Hyperterminal" (9600-8-N-1) Mode: auto detect

    Openscale is reporting data (yay!) However, TYPING "x" DOES NOT BRING UP the OPENSCALE MENU. All typed keys are ignored.

    Any ideas on how to access the command menu? Thanks

  • Member #779822 / about 6 years ago / 1

    Please help a noob out:

    We have the openscale board and load sensor connected OK

    Now we are trying to figure out how to see data values in hyperterminal window I assume the "trigger character [48]" refers to the switch that turns data sending on/off - ? Ascii 48 = "0" (zero) - but typing zero has no effect - it merely displays the openscale command menu

    Calibrate produces a scrolling list of real time data values, but we can't figure out how to turn on the data outside of the calibrate function. Thanks

    • LightningHawk / about 6 years ago / 1

      Did you also turn "Serial trigger [on]"? In the configuration menu enter 't' and it should turn on.

      • Member #779822 / about 6 years ago / 1

        Yep All we can get is the command menu

        Serial Load Cell Converter version 1.0 By SparkFun Electronics No remote sensor found System Configuration 1) Tare scale to zero [5244] 2) Calibrate scale [-331572] 3) Timestamp [On] 4) Set report rate [847] 5) Set baud rate [9600 bps] 6) Change units of measure [lbs] 7) Decimals [4] 8) Average amount [4] 9) Local temp [Off] r) Remote temp [Off] s) Status LED [Off] t) Serial trigger [On] q) Raw reading [On] c) Trigger character: [32] (space bar - just reprints menu) x) Exit

        • LightningHawk / about 6 years ago / 1

          Do you see data when you don't use the trigger? The only thing I can suggest after this is to call our tech support team or if you don't mind sharing your sketch I can try to recreate the problem and troubleshoot as well.

  • Member #1308434 / about 6 years ago / 1

    Does anyone know why I can't open the Terminal to access the Smartfun Openscale via a Windows Computer? The board's blue LED light is on and it is plugged in but my computer does not show it on my device manager, so I can't access it via putty. Any suggestions?

    • LightningHawk / about 6 years ago / 1

      If it isn't showing up on device manager it may be a driver issue. Do you have the FTDI drivers installed?

  • Member #1279604 / about 6 years ago / 1

    I am using the Openscale connected to 4 load sensors (50 kg), which is feeding information to an Arduino MKR1000. However, I'm having trouble actually getting the data to read correctly from the Openscale to the Adruino. I was able to get accurate readings from the Openscale's HX711 itself, but once connected to the Arduino the serial data isn't reading correctly.

    Between the Openscale and the Arduino is a bi-directional stepdown/stepup converter due to the Arduino having a max of 3.3 volts and the Openscale being 5 volts.

    Is there any direction I should be looking towards to see about how to get the data to read correctly, or even how to make sure I have everything wired properly?

    Thank you in advance.

    • It sounds like OpenScale is working correctly. The OpenScale runs at 5V so you are correct in needing a TX/RX converter. I'm not sure how you have the converter wired. I'd recommend our logic level translator for serial.

      I've always been a big supporter of logic analyzers. They'll show you what's getting through to the MKR and vice versa. I love my Saleae but they've eliminated all their lower-cost models.

  • Member #1000437 / about 7 years ago / 1

    I am using a 10 kg max load cell (TAS606-10kg miniature button type load cell) and the weight seems to be off by quite a bit.

    I have a nickle, dime, and quarter which I am trying to measure grams on. I am finding that the readings re off by a factor of 5-6x.

  • Member #1079133 / about 7 years ago / 1

    Hi there, does anybody tried to "post process these temperature readings to get the maximum scale accuracy" ? I've found nothing, nobody on the net doing so (how bizarre??) !!

    Up to now, I'm doing over day measurements with fixed (known) weight and try to estimate the temperature correction factor with a linear or 2nd order polynomial regression formula given by Excel sheet. Yet results (corrected curve) still follow the measured curve (not flattened by this correction factor) can someone point me in the right direction please ? thanks in advance :-)

  • Member #952179 / about 7 years ago / 1

    How do I hookup the HX711 to the OpenScale board? thx

  • Member #911563 / about 7 years ago / 1

    Hi. We have a load sensor with 3 wires (red, black and blue). We use the Openscale and we follow all the steps in the tutorial. We can set options for the Openscale thanks to arduino but we don't receive any values of reading. Can you help us please? Thanks, Antoine

  • Member #853400 / about 7 years ago / 1

    Hi, Does anyone know how to maintain the tare weight (zeroing) of the load cell even after power cycling? Everything else seems to maintain its settings like calibration, decimal, etc but not the tare weight.


  • Member #841275 / about 8 years ago * / 1

    Hi, I've got my open scale setup, and was reading it correctly, and now for some unknown reason, My scale is fared and immediately jumps 15-20 pounds. I'm using 4 50kg sensors and the built in combinator. Any ideas? Thanks!

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