Excessive Run-Time Delay

[Tebefia]

Folks, I need help to troubleshoot the excessive run delay with my application.  Here is a description of what is going on.

1. I have an Analog Input voltage task consisting of 16 channels. 

2. I have my Number of Samples per channel set at 128, and Sample Rate (samples per seconds) set at 1024.  Am doing Continous mode of application, and am using USB 6218 as my DAQ device.

3. I have an Event structure in my application with Event Timeout as 10ms.

PROBLEM:

The problem am currently experincing is that whenever I open my application and click on RUN to tun the application, it takes at least 2 minutes before I start seeing plots on my waveform charts even while the continous RUN button is showing black indicating that the application is running.  When the application starts plotting signals on my waveform charts, it begins as a very fast stream, and the slows down/settles on a steady average speed after some few seconds.  I still can not figure out why it takes about two minutes to start plotting my signals even when the application is showing that it is running and when it finally starts plotting, it comes with a very fast speed.

I would appreciate any troubleshooting hint.

Regards 

[RavensFan]

Post your VI so we can see how it is setup.

Are you actually saying you are using the Run Continuously button instead of the Run button?  If so, don't.

[Dennis_Knutson]

A clue to an incorrect design is your mention of the run continuous button. This should never be used except in special debug situations. You should certainly not use it with an event structure. You need to explain why you think you need the event structure and post some details on your code. You haven't even posted an image of the block diagram. The best thing would be to attach the VI.

[CoastalMaineBird]

I've seen this sort of thing before.  Don't remember the exact cause but it's something to do with the USB driver.  Basically, my data was piling up in the USB driver until something burst and then it all flowed out very fast.

In my case, the first data you SAW was indeed the first data RECORDED, quite a few seconds ago.  Something to do with Windows settings, if I remember correctly.

I will check my e-mail archives and report back soon.

[CoastalMaineBird]

This post has some info, mentioning a USB SLEEP setting in Windows.  Not sure if that was the final resolution for me.

[CoastalMaineBird]

Well, I cannot find email with a definitive solution.

This was 3 years ago.  I believe it had to do with a Win XP setting for USB sleep.  It might have been fixed with a move to Win 7.

Are you on Win XP?

THat's all I have, unless you want some debugging suggestions.

P.S. I agree with the "don't use the REPEAT RUN button" comments by others.  That should not be used in general practice.

[Tebefia]

Folks, thanks for all your comments and responses.  I am not using the RUN continously button, but of course the RUN button.  What I meant to say is that my acquisition is in continous mode, and when I click on the RUN BUTTON to run my application, while it indicates that my application is already running (RUN button changed to black color), I don't see my signals plotted until more than two minutes, and when the signals starts to plot on my waveform charts, it plots with fast stream of data for few seconds, before slowing down to a steady speed.

I agree that attaching the vi might make more meaning for any help, but I can't do that cos of company policy, hence am just trying to explain the problem.  

Regards.

[CoastalMaineBird]

The problem my customer experienced (I never saw it) three years ago would ONLY manifest:

A) on program startup, and

B) after waking the thing from screensaver.

We proved that when it woke up, it "played back" the data it had stored while it was asleep.

Can you prove/disprove that same behavior?  If you quit the program and start right up again, does it work normally?

If it's the sleep thing, then it will, because the USB driver won't have time to power down again.

Do you have access to the source code?  If so, you can insert some indicators to show whether it's really receiving data and not plotting it, or not receiving it at all.