What is equation based calibration?

[Heartthief]

Hi, I want to know what is equation based calibration and how i can do it on NIFieldPoint data acquizition device using Measurement Studio 7 in VC++
Best Regards

[Kevin_S]

Hi Surender,

You can of course perform a software calibration in your VC++ code.  This would probably be the easiest.  (You could offset the incoming data, apply a gain, or both.)

As far as doing this outside of your code and accessing the scaled changes, that is a bit harder.  You can make scale changes in the Measurement and Automation Exporer (MAX), but these changes are stored in a configuration file associated with MAX (in the *.iak file).  In order to get those scales to the FieldPoint, you would need to use LabVIEW or LabWindows/CVI.  These are the two programs that can use the NI FieldPoint driver and transfer that configuration file from MAX to the FieldPoint.

I hope this helps,
Kevin S.
Applications Engineer
National Instruments

[Kevin_S]

There are also two different ways for a user to perform a calibration.  (Not all NI hardware necessarily supports both methods.)

1) You can set up your hardware and perform a read.  You can tell the device what value it should be reading, and based upon what it reads and what you tell it the correct value should be, it can offset the incoming data.  When you do this with 2 or more points, an equation is created, and the device calibration can extrapolate what other input values should be based upon your 2 or more calibration points.

2) You can specify an equation directly with a gain or offset.  Whatever value is input will be changes according to the equation.

Kevin S.

Applications Engineer

National Instruments