How do I do real time multi channel data logging in labview for pci 6251

[Suchit]

how do I log data in Excel or other Graphing Software related formats in LABVIEW?
I am using pci 6251 for my testing purposes. I have multi channel Analog Input and Output voltage data. How do I log all the data in some format which generates only one single file and each time new data is logged the data is stored in the same file. Any suggestions since I require to achieve data accurately and very fast enough so as to not have lossy data.

Thanking you in advance.

[Nadim R]

Hi Suchit,

There are a few options for you to log data to your excell sheet.  You can simply use the Write to Spreadsheet file.vi and use the extension .xls to save it into an excell sheet.  You can also use ActiveX controls to programmatically log data to the sheet.  This option is for more advanced users who are familiar with activeX--  There is an example in the example finder under help called "Write table to XL.vi".


I hope this helps,

Regards,

Nadim
Applications Engineering
National Instruments

[Dennis_Knutson]

Fast Excel Logging is an oxymoron.

Using ActiveX to save a native Excel file is the slowest and saving as a comma or tab separated text file is the next slowest. Saving to a single file can also be a problem since you have a limitation on how many rows Excel can import (64k I think). What scan rate will you be planning to use, how many channels, and how long do you intend to run the acquisition?

[Suchit]

I am supposed to do 4 wire measurement so I have hooked up 4 input and 2 output channels. The readings I am supposed to take is large enough around 1E5 - 1E8 data with 8 different sorts of measurements to be taken.  So do you think I have any other option which might not be fast enough as comma or tab separated file but can store large chunks of data and still can be read in Excel or Graphing software directly?

[Dennis_Knutson]

If the "Graphing" software you are talking about is LabVIEW or some other advanced analysis tool like Matlab, then yes. Excel is a very limited tool and with these number of points you are also going to have to watch out for the 2GB limitationin LabVIEW. What you will need to do for the fastest way to save and to make the smallest file, is to save your data as binary. Most advanced tools have the capability to read binary files and with LabVIEW 8.2, you can save them in the same endian format that other windows programs expect. There are several shipping examples on binary file storage and streaming to disk.

[Herbert Engels]

Fast logging to Excel used to be an oxymoron ... until LabVIEW 8.20

You can use the TDM Streaming API to log to TDMS files at a very high speed. You can then go to https://www.ni.com/en/support/downloads/tools-network/download.tdm-excel-add-in-for-microsoft-excel.... and download the Excel-AddIn that loads TDMS files into Excel. The only thing you need to be careful about is the number of values, as Dennis pointed out.

Hope that helps,
Herbert

[Dennis_Knutson]

I really got to get 8.2.

[Suchit]

err..i also use labview 8.0

[Herbert Engels]

There's still hope

You can do the same thing with the older TDM file format. You can create TDM files either with the Storage VIs or with the "Write To Measurement File" Express VIs. These approaches will not achieve the streaming performance you can expect from TDMS though. If you need to stream to TDM files really fast, have look at this link for how to do that:
https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000x4PcCAI&l=en-US

TDM support goes back until LabVIEW 7.1.  The Excel AddIn is the same for TDMS and TDM.

Hope that helps,
Herbert

[Suchit]

which is more faster? Reading Data using Built in VI NI-DAQmx or configuring independently each NI-DAQ vi's for reading data from the channels. How do i use the advanced Property Nodes? Are there any tutorials for making best use of them for my project?