Hello, i am pretty new in the node red topic and currently trying to get the weight of my hx711 load sensor in node-red but i am not able to do it. I saw that there is the palette node-red-contrib-hx711 which looked easy to use but i only get 0 values even with the given flow of its github entry. I also tried it directly over python on my raspberry pi - there it works to read the load but i am unable to get the data into nodered
nodered v 3.1.3
nodejs 18.19.0
flow:
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"fnCode": "#! /usr/bin/python2\n\nimport time\nimport sys\nimport RPi.GPIO as GPIO\nfrom hx711 import HX711\n\nhx = HX711(5, 6)\n\n# I've found out that, for some reason, the order of the bytes is not always the same between versions of python, numpy and the hx711 itself.\n# Still need to figure out why does it change.\n# If you're experiencing super random values, change these values to MSB or LSB until to get more stable values.\n# There is some code below to debug and log the order of the bits and the bytes.\n# The first parameter is the order in which the bytes are used to build the \"long\" value.\n# The second paramter is the order of the bits inside each byte.\n# According to the HX711 Datasheet, the second parameter is MSB so you shouldn't need to modify it.\nhx.set_reading_format(\"MSB\", \"MSB\")\n\n# HOW TO CALCULATE THE REFFERENCE UNIT\n# To set the reference unit to 1. Put 1kg on your sensor or anything you have and know exactly how much it weights.\n# In this case, 92 is 1 gram because, with 1 as a reference unit I got numbers near 0 without any weight\n# and I got numbers around 184000 when I added 2kg. So, according to the rule of thirds:\n# If 2000 grams is 184000 then 1000 grams is 184000 / 2000 = 92.\nhx.set_reference_unit(450)\n#hx.set_reference_unit(referenceUnit)\n\nhx.reset()\n\nhx.tare()\n\nprint(\"Tare done! Add weight now...\")\n\n# to use both channels, you'll need to tare them both\n#hx.tare_A()\n#hx.tare_B()\n\n# These three lines are usefull to debug wether to use MSB or LSB in the reading formats\n# for the first parameter of \"hx.set_reading_format(\"LSB\", \"MSB\")\".\n# Comment the two lines \"val = hx.get_weight(5)\" and \"print val\" and uncomment these three lines to see what it prints.\n\n# np_arr8_string = hx.get_np_arr8_string()\n# binary_string = hx.get_binary_string()\n# print binary_string + \" \" + np_arr8_string\n\n# Prints the weight. Comment if you're debbuging the MSB and LSB issue.\nval = max(0, int(hx.get_weight(5)))\nprint(val)\nmsg = val\n\n# To get weight from both channels (if you have load cells hooked up \n# to both channel A and B), do something like this\n#val_A = hx.get_weight_A(5)\n#val_B = hx.get_weight_B(5)\n#print \"A: %s B: %s\" % ( val_A, val_B )\n\n#hx.power_down()\n#hx.power_up()\n#time.sleep(0.1)\nGPIO.cleanup()\nreturn msg",
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