Overrun error (-1073807252) occurs after several minutes

[zumer]

Hi,

I have experienced the same problem when I want to read 6 serial signals. I found out the following:

- there might be the problems if all of the ports on the USB hub do not have their own TT or if they are not all on the same TT (you can see this in device manager under USB hub),

- in the code, after serial configuration I added Visa Clear and then Visa Open command, then it works,

regards,

Jurij

[eximo]

I am having the same symptoms that suggest that the error message is unrelatd to the computer's memory buffer.

It is obvious that if you wait long enough and don't service the uart that it will eventually fill up with data.  The way around this is to unload the the memory buffer frequently enough not to overfill it.  But what if you are sure you are not overfilling it and that there is another problem.

Symptoms:

Uart at 55555 baud rate with 14 bytes arriving at 125 hz, problem not observed.

Uart at 112600 baud rate, 14 bytes arriving at 250 hz or 333 hz.  Problem observed  intermitantly, sometimes in a few seconds, sometimes in a few minutes.

Proof the memory buffer was not full.

Use the "Bytes at Port" visa property found on the serial pallete to read out how many bytes are at the port at any given time. Connect an front panel indicator to each of the Bytes at Port and monitor the values.  I also included the Baud rate, and other properties just to be certain that I wasn't inadvertantly making some other change in the program that causes this.  Place one before and one after the Visa Read function.

The Memory buffer by default is 4092, but I set it to that value just to be sure that it wasn't being changed.  When the error occured it never was more than 400 bytes.  Just by scrolling my mouse I could push the number of bytes in the buffer over 3000 without causing an overrun error.  In other words, the error message is not indicitive of the memory buffer being overfilled.  

Theory:

Just as Dave_thomas suggested.  Dave may be right that the error is either totally incorrect or that it is indicating that the small bufffer of the UART chip is not being serviced by the CPU fast enough to keep it from overfilling.  

This may or may not be a labview issue, it may be a windows issue.  It would be nice if the labVIEW developers could provide a more informative error, or determine if there is a bug in the visa system since this has been rattling peoples cages for at least 6 years now.

-Joshua White

-Neuronetrix

[schesco]

if you have NIMax assistent tool ....just click on the Com port of your configuration and change the Baudrate. its must be exatly the same like your externe device