Thanks to all that answered my previous question.
If i do not require great precision, may I use the data of the lod cell and of the acqusition system (sensitivity, offset, V applied ecc...) to determine the scale ? In the other case, calibration mus be performed in factory for every device, the multiplying constant kept in an eeprom. Is that correct ?
Usually the scale factor is fairly well controlled, though it will vary from cell to cell, so for highest precision you'll need to measure it.
The offset, though is usually quite large compared to the output range. It's best to determine this by taking a measurement with no load applied, and subtracting this from the readings under load. This can often be done as part of the measurement cycle.
If the load is present all the time, you will have to calibrate the cell across the temperature range, and measure the temperature as well as the cell output.
V applied- DON'T assume this is constant. Either use a ratiometric ADC (best) or read the cell voltage when you take the readings. Use Kelvin connections for the voltage measurement to eliminate lead resistance errors.
Paul Burke
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