Load cells

[Enzo]

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 ?

 

[Paul Burke]

Enzo wrote:

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