12-26-2007 08:26 PM
12-26-2007 08:36 PM
one more update about my post.
I did another test on counter read operation (counting edge) and found no difference between finite and continous mode. both return very fast and the DAQmx Read Property node return 5 exactly.
It looks like DAQmx treat counter and AI by different ways.
12-28-2007 03:01 PM
12-28-2007 03:55 PM
04-08-2014 10:52 AM
Hi Vanessa L
Related about the operation mode of DAQ, I need to acquire the data which is changing very fast so that why I bought a NI card model: USB 6341 X series from National Instrument and I expected high speed acquisition since on the specs they said 500 ks/s that why I chose it.
I am new with Labview and I wrote a simple program for my application that you can see in attached file. I have two inputs, I used Assistant DAQ to acquire the data. all I want is to take the data, put it in a text file, that's all. I chose the "Continuous Samples" mode of DAQ and the speed I saw it just 2Ks/s then I switched to 1 sample (on demand) mode it was even lower. I tested with all modes, the fastest one is Continuous Samples like I mention above but it doesnt sastisfy my application, I need much higher rate.
If you know how to use the card properly to use up the rate as indicated on the specs.
Many Thanks
04-08-2014 11:02 AM - edited 04-08-2014 11:03 AM
All of DAQ settings are hidden by the DAQ Assistant and all that you posted was an image. For high sample rates and continuous mode, you will probably have errors if you are saving to a text file. Are you also doing that? You should be streaming to file in binary or using a producer/consumer architecture.
04-08-2014 11:08 AM
You are not likely to get that kind of speed with blue boxes on your block diagram.
Go through the example finder and look at the "Voltage (with events) - Continuous Input.vi" since, you are not likely to get a lot of speed out of a text file either. TDMS logging will help a lot.
04-08-2014 11:39 AM
Hi guys,
Thank so much for your quick responds. Here is my IV file. Yes, I did save data in a text file and I got error after around 20 s of measurement if I selected Continuous mode (that chose by right clicking on Assistant DAQ then selected the mode) . I thought that error means it does not have enough memory for the data.
So I can still use the Assistant DAQ with the continuous mode and only change the way to save the data then I can get higher rate?
P/S. My application is to acquire the data just in 1 or 2 second but the switching time very fast so I need as much meaning data as I can. Until now I had only 2 good points, sure that is not enough.
Thanks
04-08-2014 11:55 AM
You are only reading 1 sample at a time. Try reading 100 at a time at the 1 kHz sample rate.
04-08-2014 12:00 PM - edited 04-08-2014 12:08 PM
Try something more like this:
to get there I first right-clicked on the DAQmx assistant and selected "Convert to Task" and configured the task to stream data to disk as it is read. Then I tosssed out all the rest of the express vis since the DAQmx task does everything you wanted it to do.
Edit: Attached backrev saved to LabVIEW 2010 per source vi I do not know if the logging functions work that far back but the conversion did not toss up any warnings. other than the expected " some Polymorphic instances.." of the configure logging vi have required terminals. So if its broke in 2010 you may need to relink to the correct poly instance