Select a Vi to acquire, save and read continuous analog voltage

[Intern2005]

Hi,

i'd like to get a Vi to acquire a continuous voltage in a chart or graph to measure a load cell. I would like to save it in binary format (ASCII) or DIadem format and then to be able to display and use it in Diadem.

I have already tried lots of vis but it is not easy to find one that can do all those functions.

At the momemt I am using the Continuous Acq&Graph Voltage-Int Clk and I mixed it with other vis to be able to save it in a binary file. So at the moment I can save it witout errors if the samples number, the frequency rate and the loop time are not too high.

But I have sometimes errors and I don't know how to read this saved file in LabView or Diadem.

In Labview the VI that normally read binary file (graph or chart) doesn't read my chart...?

[Intern2005]

Please see other pictures enclosed

[Intern2005]

I would appreciate a quick answer, thanks very much

[Ulrich_Bierwisch]

Hi,

the easyest way to get this done is by using Express vi's. Just start with a blank vi. You only need one vi to aquire the data, a graph and the vi "Write to Measurment File". Finally you put a loop around everything and you are done.

The Measurment file has an easy to read ASCII - format and DIAdem is prepared to read it directly. In most cases this is fast enough.

Sorry for not submitting an example, but it's not possible right  now.

[Intern2005]

Hello,

Thanks, it's working properly with this solution.

But I would like to know how I can acquire data continuously, I mean from 0 until the user press stop and to be able to visualize with the X scroll bar. Becasue when I open the file saved *.lvm I just can see the temporary acquired graph and unfortunately not all the chart history length???

Have you got an idea?

And then could you tell me how I can export this data to Diadem (ia have version 8.0)

Thanks in advance

[Ulrich_Bierwisch]

The "Write to Measurment File" vi has to be placed in the loop. Outside of the loop, it will save only the values of the last iteration.

There are lots of parameters to control what will be saved to the file. You can look to the file with ASCII-editors and check this out with a few simple tests.

I think DIAdem 8.0 is to old to be able to read *.lvm directly, but the files are simple enough to be imported with the ASCII-import. I recomend to use "Write to Measurement file" with "one X-column only", "no headers" and Comma as delimiter. The result should be a file which can be imported almost directly with the ASCII-Import.

There are also some vi's to save values into the *.dat format of DIAdem. This would make it very easy to load them into DIAdem, but they are not  that simple to use in LabVIEW. If you are working on a LabVIEW-Projekt to be used often an for a long time, it still might be a better solution to put the efford into this area (or to update your DIAdem to todays version 9.1).

[Intern2005]

Ok thanks, it seems to be working well now

Thanks, you're the a genius

[Brad_Turpin]

Hi Intern2005,

For continuous streaming, I would recommend to create the binary data file yourself with the standard LabVIEW file I/O VIs, then create a header file to describe the binary file that you've streamed.  Here you have the choice of a TDM header file or a DAT header file.  The DAT header file approach requires downloading the LabVIEW-DIAdem Connectivity VIs.

The TDM header approach requires using a new set of TDM header VIs wrapped around a C++ DLL, which you can not yet download, but which I'm providing below.

Both approaches are wrapped up in the ZIP file below, with examples, and both approaches are 100% readable by DIAdem.

Ask if you have questions,
Brad Turpin
DIAdem Product Support Engineer
National Instruments