write waveforms to file.vi

[vtince]

Hi, I want to know if used Labview 2010 and used the Write Waveform to FIle.vi, will I be able to open that saved waveform file with NI Analog Waveform Editor?  Also, what extension is the saved waveform file? I am unable to find it. Thanks!

[Julianne_K]

Hi vtince, 

The Write Waveform to File vi write the raw data to any file type you chose, but it is typically a text file. Unfortunately the HWS file type has a different format. What kind of hardware are you using? Some instrument drivers include functions for writing HWS files, but these are not included in the base package. Also, why do you need to build the waveforms in LabVIEW? Is there a reason you can't build them using Analog Waveform Editor? Thanks, 

[vtince]

Hi Julianne,

Our company had just purchased Analog Waveform Editor, and it hasnt arrived yet, so thats why I'm using Labview. What I want to do is to record a 2-channel signal, then have the option to edit parts of the signal and output it back. I am also using the USB-6211 to aquire my signals.

What do you suggest? Wait for the Analog Waveform Editor and use that to aquire and edit the signal?

Thanks

-Vince

[Julianne_K]

Hi vtince, 

There are functions available for writing HWS files, which are included in the NI-HSDIO Instrument Drivers. You can download NI-HSDIO here: 

http://joule.ni.com/nidu/cds/view/p/id/2217/lang/en

Please make sure you have the correct system requirements for this download. After installing the drivers, there are several functions which will appear on your LabView Palette, which include NIHWS Write, NIHWS Open, etc. These are located on your front panel under: Express -> Output -> Instrument Drivers -> NI-HSDIO -> Dynamic & Static Generation -> NI Hierarchical Waveform Storage -> niHWS Low Level Write.

Also, you can go into the Example File (go to Help -> Find Examples which your vi is open) and find the example called "Acquire and Save to HWS File". This example should show you how to write to an HWS file using the new functions. You should be able to integrate this functionality into your current program. Let me know if this helps and best of luck,   

[Julianne_K]

Hi vtince, 

Here is a great resource for using the Analog Waveform Editor and HWS Files with Multifunction DAQ Devices, which should help you when the AWE comes in. Sincerely, 

[vtince]

Thank Julianne,

I have just installed NI-HSDIO, and used the NI-HWS Express Save to save my data. I am gathering a 2-channel data (channel 0 and 1) with DAQ Assistant and using the Express Save to save a HWS file. However, when I open the HWS file with Analog Waveform Editor, I only see the first channels (channel 0) data. Is there a way to save both channels onto the HWS file? I also get a this message when I open the HWS file, " The selected file contains HWS data, but does not contain waveform specifications this editor can read. The waveform will be imported into the editor as arbitrary data".

I have attached a picture of my block diagram.

Thanks,

-Vince

[Julianne_K]

Hi Vince, 

With the HWS file format, you are only able to save one waveform per file. So if you want to support both channels, you need to make a HWS file for each waveform.

Regarding the message that you receive, when you create the HWS file, the only information you provide is the waveform. The Analog Waveform Editor (AWE) uses additional information, such as the sample rate and device type, which is why it prompts you for this information when you click ok on the message. If you save this waveform in AWE and open it again, you will not longer get this error. Does this explain your issue, or would you prefer to specify this information in LabVIEW? 

[vtince]

Thanks, you have been a tremendous help. It was a simple fix, I just split the signal into another Express Save. I can now edit both waveforms separately in AWE and am able to use the Express read to open each file and merge the signal for output playback.

Thanks again!

-Vince