niScope: access gain offset

[Frederic - Munchen]

I use niScope 2.5
I have a problem to access the gain/offset values in a while loop where the acquisition VI is located (Fetch 16-bit). If I directly multiply do wfm (=my data 16-bit)*gain + offset I get the voltages and it is ok. But I want to use this parameters after the end of my while loop and they are set to 0 !. It is the same if I want to put these values in an array at each iteration : the array is full of 0!
It seems that if you do not use the gain/offset just after the measurement (independently from the data in bit format) you can´t access them.
Can you give some advices have at least one different from zero.
thanks

[Brent_R]

Hello Frederic,

Please take a look at the LabVIEW shipping example called "niScope EX Binary Acquisition.vi", which can be found through the LabVIEW example finder or directly in the LabVIEW examples directory. This example fetches binary waveforms from a multi-record acquisition and then scales the data using the gain and offset returned in the "wfm info".

I have tested this example with both the 5112 and 5122 digitizers and have found that the "wfm info" appears to return the correct gain and offset values during each iteration of the acquisition loop (they remain constant). If you would like to query the gain and offset values after the loop, you can add an additional fetch vi anywhere before the scope session is closed.

The gain and offset v
alues are typically very small numbers, in the range of ~1e-4 for the offset and ~1e-3 to ~1e-2 for the gain, for an 8-bit digitizer (5102, 5112). The values are even lower for the 5122. It is possible that the front panel indicators are set to display an insufficient number of digits and display is rounding to 0.

Regards,

Brent R.
Applications Engineer
National Instruments