Retrieve custom scale properties from Measurement and Automation Explorer (MAX)

[udo.raupenstrauch@partner.bmw.de]

Hallo together,

For my measurements I am using a DAQmx Card with custom scales. Due to changing ambient conditions i have to rezero (tara) from time to time. The scales representing the original calibration data of the transducers are saved in MAX and for rezero i'm shifting the min and max scaled values of the active DAQmx map range scales by a measured offset.

It works excelent.

My problem occurs when i'm trying to reset the DAQmx scales to original scale data from MAX.

There is no function to either retrieve persisted (saved) scale properties from max or a function to delete a DAQmx scale.

The persisted scale property node provides only the properties:

    "Author", "Allow Interactive Editing" and "Allow Interactive Deletion".

There is no way to retrieve properties like "Pre-Scaled Minimum Value", "Pre-Scaled Maximum Value", "Scaled Minimum Value", etc. for a persisted scale.

I've attached an example vi to illustrate my problem.

The thread: http://forums.ni.com/ni/board/message?board.id=180&message.id=2659&requireLogin=False

and             http://forums.ni.com/ni/board/message?board.id=230&message.id=481&requireLogin=False

deliver an example of what i need.

I need a similar function or vi in LabVIEW for a map range scale and not for slope and intercept scales.

Thanks!

Best Regards,

Udo Raupenstrauch

[Philipp N.]

Hello udo.raupenstrauch,

it is really interesting that it does not seem to work to get these values. I also experimented with some vis. You are able to read out which scales are available in MAX or you can open one with the scale name constant, but when you wire it to the invoke node you can only use one of the three parameters you wanted to have (you only get scaled units but not the two others).

I will try to find out if there is another solution or if it was simply "forgotten" during development. Until then I think you need to use the scale when you start the DAQmx task.

Best regards

Philipp N.

NIG AE

[Philipp N.]

Hello udo.raupenstrauch,

a colleague had the same issue and found out, that it is not possible to access these properties in MAX in the same way. This is because the developers wanted to avoid messing up the data in MAX with a LabVIEW program.

Best regards

Philipp N.

NIG AE

[udo.raupenstrauch@partner.bmw.de]

Hallo Philipp,

thanks for your effort !

I have an additional answer from NI, which i refuse to accept : "This is a good thing - we want to protect customers from programmatically messig up their settings"

I will continue to search for a solution because i'm not trying to change (mess up) saved data, what's wery well possible with the vi "SavePersistedScale" or "DeletePersistedScale". I'm just trying to retrieve already saved scales.

This functionality is available (somewhere), while the function "CreateScale" retrieves this data from MAX at each start of LV, of course only if the scale is present in MAX.

Thanks again and best Regards,

Udo Raupenstrauch