How can I save data directly on the cRIO 9076?

[Loksche]

Hi LabVIEW community,

I want to run a stand-alone application with my cRIO 9076. Therefore, I want to save data directly on the chassis which caused problems in my application.

I need to do that for two different cases.

1. I want to save data of the calibration (in form of DBL inside of clusters) which I carry out when the chassis is still connected to the computer.
I load this data from the chassis into the HostVI which runs later as the stand alone application to process my signals.

2. I want to save the the occurring strain (NI 9235) and accelerations (NI 9234) in the stand alone application.

To 1)

I tried to save the values of my calibration (e.g. Offset values, Correction factors) into shared variables which I read out in the HostVI.
However, everytime the chassis is powered off the variable loses its content.
To solve this by typing the values manually as an initial value into the variable (possible with the DSC module) is not an option for my application since it would take too much time to do that.

I tried then to use the datalog VI's which also caused problems due to that it requires an absolute path whereas the chassis is a relative one.
Using the "Build Path" option (see attached screenshots) enabled the programme to create the file and save data into it but for some reason it works only sometimes (in the normal case it reads only zero's out of the file).

To 2)

I try to save the strain and acceleration plots with the TDMS VI's. However, after running the programme an error message occurs that states that "Manager call not supported" (Error 53 at TDMS write, see screenshot).

I would be grateful if someone could tell me how I can save the data in both cases.

Thank you in anticpation.

[YongqingYe]

Hi Loksche,

For the error code 53 of TDMS Write, did it happen when your application started running or happened some time after the application running? Since your cRIO 9076's disk size is limited, is it possible that the hard disk is full when the error happens? If not, it it covenient for you to post the reproduciable VI here for us to do more investigation?

Thank you!

Yongqing Ye

NI R&D

[Loksche]

Hi YongqingYe,

Thank you for the quick reply.

The error 53 occurs at the end of the application when I want to save my waveform into the tdms file. There is also more than 200MB free hard disk space available on my cRIO. So that can't be the problem.

As requested, I have attached the VI's (subVI calibration, HostVI).

Please let me know if you have any questions in regard to the code.

Thank you very much.

[mahu]

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I tried then to use the datalog VI's which also caused problems due to that it requires an absolute path whereas the chassis is a relative one.

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If you want to store data or files into your cRIO only need write c:/ for the absolute root path.
This hardware use path like Windows, therefore you can create directories too

[Loksche]

Hi Mahu,

Thank you for your reply.

However, your advice equals my approach with "Build path" (but yours is shorter and more convenient). Therefore, the problem still remains. The VI (calibration) creates a file on the chassis as it is supposed to be. However, it looks like that the chassis/main programme struggles to read the values out of the file. Occasionally it reads the correct values out but mainly only zeros appear.

[zaizhou.ma]

Hi  Loksche:

I look into the VI you provided. You will write the extended float into tdms file, but sadly on cRIO, TDMS haven't supported ext-float yet. So far, TDMS support ext-float only on Windows and Pharlap.

Thanks,

zaizhou.ma

[preston_johnson]

I would back up a bit, and consider using the cRIO vibration data logger example:  http://zone.ni.com/devzone/cda/epd/p/id/6388  You can add the scaling and calibration items as attributes to the waveform data type, or add them as properties to the TDMS file when it is written.  You can use the underlying waveform reference (used by the vibration data logger reference design) to synchronize your measurements with the 9234 and the 9235.

Hope this helps. 

[Loksche]

Hi zaizhou.ma,

Thank you for your hint.

That solves the problem with the tdms file.