Simultaneous RS232 - DAQ operation messes serial communication

[Vijit]

I have 2 GUIs running on my desktop, one of them communicates with an embedded board via the serial port. The other one communicates with the DAQ board via NIDAQ 6062E.

The issue is that the serial comm VI works fine as long as it is running by itself. However, as soon as the DAQ VI fires up, serial commn VI starts acting crazy and returns this error intermittently.
1073807252 VISA:  (Hex 0xBFFF006C) An overrun error occurred during transfer. A character was not read from the hardware before the next character arrived.
I have tried resolving issues with this error, but that has not helped.

The Serial comm is the more important VI and it needs to run and acquire data uninterrupted. How can I set it up to do this?

TIA
Vijit

[I_I]

Hi Vijit,

If you are using simultaneous operation then put some delay(approx. 100ms) in both VIs. This error can be seen when two device drivers are trying to work very fast simultaneously, so to balance simultaneous operation delay is helpful in both VIs.

Hope this will serve your purpose.

[JasonSmith]

Hi Vijit,

The recommendations from the last post are good, and I would add to that that you should confirm that your DAQ card is configured to work using DMA data transfers and not IRQ. 

I think that the more serious problem you are seeing is that your flow control is not working properly.  Flow control is intended specifically to stop the flow of data if you are going to experience a buffer overflow.  You mentioned in your other post that you are using Xon/Xoff flow control, are you sure that this is supported in your embedded device?  If it is supported, I would recommend RTS/CTS (hardware) flow control.

Please let us know what forms of flow control are supported by your embedded controller, and whether or not hardware flow control is an option.

Jason S.
Applications Engineer
National Instruments