DAQ assistant

[AshaG]

I am using LabView 8.2 and I was trying to find out the maximum sampling rate of my data-acquisition device. I have the signal conditioning module of SCXI 1102 which has a sampling rate of 333 kHz and a USB digitizer module of SCXI-1600 which has a sampling rate of 200 kHz.
When I was experimenting with the various sampling rates, I got an error 50016- The specified window type is not valid or is inappropriate in the context of the current device configuration. But the error goes when I power off the chassis, then turns it on and try again. How can I avoid this?
I need to write the acquired data into a file and it seems to me that this is where the problem lies- I cannot go beyond a particular sampling rate as the writing slows down the whole process.
I found that the method of data acquisition in the LabView examples is faster as compared to the DAQ Assistant.
Any suggestions?
 

[ninlmartijn]

Hello AshaG,

In what file format are you writing, it is best to use a binary (binary or TDMS) file format (this is the quickest). If you are writing in a loop it is also best to use the basic (low level) write VI's and not the express write vi. With he basic write file VI you are able to put the open file vi and the close file vi outside your loop, this saves a lot of time.

Please note that the SCXI 1600 module is deciding your maximum sampling rate.

I hope this helps,

Best regards,

Martijn

[AshaG]

Thank you for your quick reply. I wanted a file format which was human readable and could be imported into different environments. Does binary/TDMS file fulfill this criteria?
Do you know why Error 50016("The specified window type is not valid or is inappropriate in the context of the current device configuration") occurs?

[ninlmartijn]

Hello AshaG,

Binary is just raw data, so only values are stored no signs or anything. TDM file formate is the same, but there are some aditional headers (Root, Group and Channel). Savng in Raw data is much faster than saving in ASCII (text), TDM has also the advantage of fast saving (and reading), but your data is also easy to manage. here is a plug in to read this TDM file format in Excel, with this plug in everyone will be able to acces your data. ou can read more about TDM at www.ni.com/tdm

I can't exactly say what this error code means. Some suggestions to resolve this problems are;

- downloading the latest NIDAQmx driver (in some versions this error is a known issue; http://joule.ni.com/nidu/cds/view/p/id/965/lang/en (driver is for Labview 7.1 or higher)

- try to swap the modules in different slots

many greetings,

Martijn