To avoid burying the lead, I'm going to state the problem I'm having straight off. The program I'm written pauses exactly every 10 seconds while running, always on a time where the seconds are around 3.6 (see below, as low as 3.4 and as high as 3.8). the pause is very short, easy to miss. I only noticed it because we recorded over the pause a few times and the data columns got swapped. The timing of the pause appears to be independant of the sample rate. I've gone as high as 200k and was able to repeat it as low as 50k. Below 50k I cannot reproduce the error reliably. Once the error does occur it happens exactly every 10 seconds (down to the millisecond). For example, on one run I get the error at 11:06:13.681, it will occur again at 11:06:23.681, at xxxx:33.681, xxxx:43.681, etc... Program explanation: Currently the software acquires data from some 9 sensors at 100 kHz, 3 sensors at 1000 Hz, controls 4 relays, and outputs a TTL signal on demand. Initially the software just monitors the sensors and writes the data to a plot. When I hit the "fire" button the software shuts of the plots and records the data to several TTL files, one for each rate. I had some problems early on with errors when trying to plot data at the same time as I was recording it. In my research on this timing issue I believe it is being caused by having the "write to measurement file" in the while loop. Not really certain of how to pull them out and stream the data to the file yet, but that's next on my list. Anyway, the program still has some evolving to do as the test program moves forward. Initially it was written using the "DAQ assistants." Again, in my research I learned that I really want to use the DAQmx functionality. I went ahead and swapped most of them over to DAQmx. As of this writing the things that are active while I'm not recording (have not hit the fire button) do not have any DAQ assistants. I'll be changing the assistants under the lower case structure to DAQmx in the near future, I'm going to figure out how to move it outside the while loop first while I know it works. Does the software work at this point? Yes, it is currently being used and recording data in a satisfactory manner. However, I know that I have to move forward with it and create additional functionality, possibly record at higher speeds, so I want to resolve these bugs. Possible causes: 1) Buffer overun. Perhaps increasing the buffer size will solve the problem. 2) PC Memory. I know win7 is a memory hog. The laptop only has 6 GB of ram, all it has on it is labview and office. 3) The DAQ assistants under the case structure are causing problems? Could it also be that I originally did this with DAQ assistants and swapped them to DAQmx with the right-click "Convert to DAQmx?" 4) I'm plotting an excessive number of points on the chart and that's causing the issue, maybe a redraw issue? I'm using a cDAQ-9188 with 3 9222, a 9221, two 9481s, and a 9402. and running LabVIEW on an Inspiron N5110 with a core I7 and 6 GB of ram and 64 bit windows 7.

LabVIEW

LabVIEW pauses during acquisition

Author

Well, I feel a bit foolish again.

I'm beginning to suspect the problem here is not with the written program but with either windows or the laptop itself.

In a fit of inspiration I decided to try "turning it off and on again" and also "unplugging something and plugging it back in."

The problem vanished.

I really wanted to know what was causing it so I started thinking about the various pieces of software I was using. I started MS Excel and ran my code again and the error reappeared, this time at 0.xxx seconds (repeating).

Even closing Excel the error persists, exactly every 10 seconds the VI pauses (freezes?) without throwing an error.

So the question here are, is Excel using a particular resource I need every 10 seconds or is the machine underpowered and Excel draws just enough to affect the performance?

Tried a few iterations of restarts and on one iteration I got the error to repeat at a higher than usual data rate without star9ting Excel (200k). On this particular iteration the error appeared when something started running in the background though, everything was running fine and the machines internal fan kicked on Labview stuttered for a couple of seconds and then the error started up (~ at 6.xxx seconds this time). Dropping the data rate to 100k and everything was fine. Started Excel and I got the error like usual at the same ~6.xxx seconds as when the 200k fan error just started.

So it appears that some resource hog on the machine is causing this.

I have the overpowering urge to format this machine!