LabVIEW

cancel
Showing results for 
Search instead for 
Did you mean: 

USB interrupt data


Hi. I'm using Labview to interface to a PIC16F450 (RAW). When the PIC sends
data (2 bytes)  to the PC every 100ms
everything works as expected. This data is graphed inside the loop shown below. However if the data rate is increased to a packet
every 6ms problems occur. The graph is no longer in sync with the actual data
being sent. The data in labview lags that being sent by the PIC. If the part is
powered off the graoph continues to update for a few seconds.



 usb_array.JPG

Is the following method for acquiring data valid?



What is the maximum data rate the VISA Get Usb Interrupt Data.vi? How does
VISA buffer the data? I saw another thread on this but it didn't answer my questions.

0 Kudos
Message 1 of 9
(4,114 Views)

Hi!

 

Why you use Timeout = 0 ms if waiting  on event? Where is the graph in the loop? You should not use a graph inside this loop.

0 Kudos
Message 2 of 9
(4,105 Views)

Hi, I am using the same way as you to get USB interrupt data, and I am facing the same issue as you (some data missed or wrong).

 

And the wait time is already set to 20ms or larger, no graph in while loop either.

0 Kudos
Message 3 of 9
(3,885 Views)

Hello mapleaf9989,

 

This thread seems to be over a year old and the original author might have unsubscribed by now. 

 

For a better chance of getting a response, please create a new posting with your VI and the errors your are receiving.  The forum users, including NI Application Engineers, will have an easier time spotting it.

 

Regards,

George T.
Senior Applications Engineer
National Instruments UK and Ireland
0 Kudos
Message 4 of 9
(3,867 Views)

Hi,

I haven't unsubscribed. I abandoned the approach I was taking above. Instead I used C++, NI VISA and a third paty graphing library which I found far easier to debug. I was able to get the performance and graphing options I required that way.

0 Kudos
Message 5 of 9
(3,856 Views)

Hi, I don't understand very clearly. Would you mind share a little on your diagram?

 

I got stuck in the Labview program now. 

 

Thanks a lot.

0 Kudos
Message 6 of 9
(3,832 Views)

I didn't use Labview. Unfortunately I can't help you with that. Maybe you should start a new thread and post the VI you're currently working on. Sorry I can't help.

0 Kudos
Message 7 of 9
(3,796 Views)

Hi 

 

I know this post was really old but would you have a sample code in C++ how you got data out from your device? I am having same issues as you had with your device. Please help. Thank you.

 

0 Kudos
Message 8 of 9
(2,766 Views)

This time, he probably has unsubscribed... It's been 6 years since the original post, so either way, OP probably doesn't have the source code handy anymore. I would suggest posting your issue as a new question in the relevant forum.

Cheers


--------,       Unofficial Forum Rules and Guidelines                                           ,--------

          '---   >The shortest distance between two nodes is a straight wire>   ---'


0 Kudos
Message 9 of 9
(2,752 Views)