uncalibrated binary data conversion (NI 9237 Module)

[gd86]

Hello,

I am trying to convert raw (uncalibrated) binary load cell data to voltage from a NI 9237 module. I have an equation and units for the equation, but they are very confusing.

The conversion is LSBW x output + Offset, where LSBW = 29783 and Offset = -1728. 

The units for LSBW are 100 fV/V per LSB for the channel, where 100 fV = 10^-13 V. The units for the offset are 10 nV/V per LSB for the channel. 

All of this info is either from the documentation or the Labview help. The LSBW and Offset were taken directly from a property node in the FPGA program. What I don't understand is the units of the offset and LSBW (I don't know what per LSB means). Are there any examples of this that I can follow? Thanks.

[christian_w]

The information you are looking for is located in the 'binary to nominal.vi' under <program files>\National Instruments\LabVIEWxx\examples\CompactRIO\Shared. Each module has its own case so that VI should give you examples for other modules too.

In the NI 9237 case you will find a factor of 1E-13 for the LSB value and 1E-8 for the offset. I think its easier for the vendor to store the calibration data as U32 or I32 in the module and provide the factors for the calculation ( LSB = LSB Weight * LSB Factor )

http://en.wikipedia.org/wiki/Least_significant_bit

Hope it helps

Christian