How to convert voltage to a physical units

[dromar2222]

Hello all,
I hope you are all doing well and safe.
I want to convert voltage to physical units.
I use a sensor of illuminance connected with NI9205:
power supply: 16 40 Vdc
Range: 0.2 20klux
Ouput 0 10 V
the results are displayed in volts and I want them displayed in lux

any help please!

[santo_13 · Accepted solution]

The scaling factor will be typically provided in the calibration report.

Assuming that 0.2klux is represented by 0V and 20klux is represented by 10V, you can find the rest of the values by the y=mx+c equation (assuming linear scaling)

You can compute m by two-point line equation,

m = (y2-y1) / (x2-x1)

m = (20-0.2) / (10-0) = 1.98 klux/V

c is the offset at 0V, which is 0.2klux

klux = 1.98 x (voltage) + 0.2

[paul_cardinale · Accepted solution]

Maybe this.

[JÞB · Accepted solution]

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@santo_13 wrote:

The scaling factor will be typically provided in the calibration report.

Assuming that 0.2klux is represented by 0V and 20klux is represented by 10V, you can find the rest of the values by the y=mx+c equation (assuming linear scaling)

You can compute m by two-point line equation,

m = (y2-y1) / (x2-x1)

m = (20-0.2) / (10-0) = 1.98 klux/V

c is the offset at 0V, which is 0.2klux

klux = 1.98 x (voltage) + 0.2

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And since you are using a DAQmx device...

Create the DAQmx Scale for the channel using a linear Scale with your slope and offset and set the scaled units to kLux!  (The scaling actually happens just a bit faster inside the DAQmx Read call to the underlying dll.)

[dromar2222]

I appreciate your help. Thank you all