Hardware timed Dataacquisition with cRIO

[jithendra]

hi,

i am trying to develop a code for dataacquisition using cRIO. my application specifications are:

Digital Input: 1 (trigger for acquisition, i have a cRIO-9401 DIO module

Analog Inputs-2 (i have cRIO-9215 and also cRIO-9221 AI modules for this)

i need to develop  a code in which the acquisition is triggered by a pulse signal of Period=20 ms and On-time=1 ms on a falling edge

the two analog inputs are: a current waveform which is on when ever there is a trigger and shuts-off on the falling edge

                                           and the second AI is a voltage signal from an EMI sensor, the two analog inputs should be synchronized

                                           and the code should acquire 20 ms of data after the trigger and check for the trigger again, and if there is a trigger, it should start acquiring

i developed a code for this, but i am having problems with the code......

1) the code seemed to work fine for some time when i tried to test it with two sinusoidal inputs and a pulse as the trigger but when i ran it again, the amplitude of the Analog input was reduced

2) how can i save the data on the Real-time controller? can i do it by using the storage VI's in labview? which i used for storing data on my host computer. and one more thing.....

i saved the data in .tdm format and tried to convert it into .xls using Diadem, but it gave me a warning saying some information can be lost.

Message Edited by jithendra on 08-11-2005 06:38 PM

Message Edited by jithendra on 08-11-2005 06:41 PM

[Ricardo_SR]

Hello,

By running the VI for a second time, you mean, stop the whole Host VI and the re run it? Or just trigger it for the second time? When you say that it reduced, you mean in Amplitude or the number of samples? I ask this because you have "Data read" that once you write a True to it, it will always be true.  You never set it back to False, so the FPGA keeps running all the time, overwriting the "AI Data",

 

Ricardo S.

National Instruments

[daniel.roth]

Hello jithendra

We like to use the TDM-VI's like you. But we get the following message:

Deploying 192.168.1.101  (successfully deployed target settings)
Deploying _closeDataStorage.vi
Failed to download _closeDataStorage.vi
LabVIEW:  Failed to load shared library lvStorage.dll:StorageDisconnect:C on RT target device.

Download completed with errors.

Used Controller: NI9012

do we have to copy the lvStorage.dll to a special folder on the crio separately?

thanks Daniel

[AdnanZ]

Hi Daniel,

I hope you are doing well today! Currently, the LabVIEW data storage VIs do not work on real-time systems, however, there is an alternative set of VIs available to help you to write TDM header files for binary data files that work on real-time systems. You also can use these VIs for high-speed streaming, for which you need to be very sensitive to overhead associated with file I/O. The TDM Header Writer VIs can be found here.
Introduction to the LabVIEW TDM Header Writer VIs

[AdnanZ]

Daniel,

You might also find this link useful.
Acquisition and Data Logging of Vibration signals on CompactRIO system

[Bassett_Hound]

Hi Daniel,

To add to what Adnan mentioned.  The TDM Data storage Express VIs are not supported on Real-Time targets. However, in LabVIEW Real-Time 8.20,  TDM Streaming (TDMS) streaming VIs were implmented for NI LabVIEW Real-Time targets that are based on the Pharlap OS which includes cRIO 900x targets.  Unfortunately TDMS has not yet been ported over to the VxWorks Real-Time targets which includes the cRIO-9012 target and is the reason you get the download error as VxWorks does not support dlls.  You can read more on TDMS and the features supported by NI's VxWorks targets below.

TDM Streaming (TDMS)
http://zone.ni.com/devzone/cda/tut/p/id/3539

Supported Features on Vxworks Real-Time OS
http://zone.ni.com/reference/en-XX/help/370622D-01/lvrtconcepts/rt_unsupportedvxworks/

Hope that helps,

Steve

[alsoACS]

Steve,

Is TDMS still unsupported on VxWorks platforms in 8.2.1?

Thanks!

[Bassett_Hound]

Hi Allen,

Yes, TDMS is still an unsupported feature on VxWorks targets in 8.2.1. Keep checking the Supported features on VxWorks targets.  This should be supported in a future release.

Regards,

Steve