VISA write not working consistently

[kniffing]

Hi,

I'm using labview to send an ASCII character via serial port to trigger a PIC microcontroller to output a TTL pulse. It works the first few times I run the vi, but then it just stops working and I'm not sure what the problem is. I suspect it has something to with the VISA interface

The PIC is set for 2400 Baud and no flow control or terminating characters.

Any suggestions?

[Dennis_Knutson]

There's nothing in the VI that would really cause it stop working. However, I would recomend that in your main VI, you actually call VISA Configure Serial Port once. No reason at all to call the property node over and over again. Just have a VISA Write in your subVI.