MAX scaling is in error

[JSC]

I input a voltage to my scxi-1141, say 1.0 volts.
I use "continuous aquire to spreadsheet" vi with no MAX scaling. I read 1.0 volt.
I use the same channel input and add a custom linear MAX scale of y = 10X + 10.
With a 1 volt input, I read 19.5 volts instead of 20.
A scale of y = 1x + 0 gets the exact input back, as expected.

Exactly where is the scaling applied and why would the math be this far off?

(It's actually a 1.0535V input and reading that scales to 20.002V with the y = 10x + 10 scale applied.)



Thanks much.

[Filipe A.]

Hello;

The only thing I can think of that might be causing that is an extra offset either on the DAQ device or on the SCXI device that might be adding a DC voltage to the original value.

That might be happeninig due to a bad calibration. My suggestion for you is to use the external calibration VIs or NI-DAQ functions (depending on the programming language you are using) so you can recalibrate both devices.

Hope this helps.
Filipe A.
Applications Engineer
National Instruments