change unit with a calibration curve

[jool]

Hi,

I have aqcuired data in a 0-10 V channel. the measured value is picked up by a pressure sensor. the sensor is not completly linear and i have the data of the calibration curve. I have about 10 points from the calibration curve. my question is how to convert the data of 0-10 V into bar using the calibration curve point in DIAdem? is there a way to use some curve fitting with a specific values?

My calibration curve is

0.6202V = 100 Bar

0.9647V = 200 Bar

...

...

4.9396V= 1400 Bar

...

...

is there a function in which i can enter this vector and use it to convert the unit of the 0-10 V channel into Bar?

thanks

Gal

[Brad_Turpin]

Hi jool,

Yeah, I think you need to create a high resolution set of XY lookup channels so that you can provide your measured Voltage value and retrieve the correct scaled value from the curve fit.  If you're willing to just do linear interpolation between your 10 scaling points, I'd recommend Linear Mapping.  You could alternatively use the Approximation function to calculate the best-fit Taylor series polynomial to approximate your scaling curve.  Or you could use a Spline fit if your scaling curve has lots of features.

Once you have the XY lookup curve, then the next step will be to apply that to your input Voltage channel to get the output scaled values channel.  We can handle that as a second step depending on which of the above methods you choose.

Brad Turpin

DIAdem Product Support Engineer

National Instruments

[jool]

Hi,

it is ok if the interpolation would be linear between each point. the entire curve is almost linear.i attached the curve points in excel.

i do i create this look up table in DIAdem and then how i use it for the interpolation?

thanks

Gal