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Hardware Assembly

Now that we're familiar with the hardware on the OpenScale - IoT, let's connect a load cell and temperature sensor to start getting data from the board.

Connecting the Load Cell and External Temperature Sensor

The OpenScale - IoT has 3.5mm screw terminals to connect load cells and an external temperature sensor. It also has 0.1"-spaced PTH pins for each of these connections as well for users who prefer a soldered connection.

Most load cells will have a Red/Black/White/Green wire color code. Insert these wires into their matching screw terminal and tighten the terminal to finger tight. Some load cells use a blue wire in place of the green wire or a yellow wire in place of the white wire but don't worry, it will still work! Load cells with a large capacity or a long connecting cable may have an additional yellow shield wire for the four signal wires. If your load cell has this wire, connect it to the yellow/shield screw terminal.

With both the load cell and temperature sensor connected, your assembly should look similar to the photo below:

Photo of a load cell and external temperature sensor connected to the OpenScale - IoT

Load Sensor Assembly

If you've decided to create your own wheatstone bridge configuration with four discrete load sensors/strain gauges (like our 50kg load sensor) you'll need to use the built-in Load Cell Combinator to combine four strain gauges into a wheatstone bridge configuration. See the Load Cell Combinator Hookup Guide for more information. The markings UL, UR, LL and LR stand for Upper Left, Upper Right, Lower Left and Lower Right respectively. Just like you would see if you opened up a bathroom scale. The C mark is for the "center tap" which is explained in the Load Cell Combinator tutorial.

Scale Calibration

The OpenScale IoT must be calibrated after assembling it to get accurate weight data out of it in your preferred units. Calibration requires putting a known weight on the sensor connected to the OpenScale - IoT and calibrating through the configuration menu. The following pages give detailed instructions on calibrating the scale along with other configuration options.