PDA VISA Configuration question

[Eccomi]

Hello, I'm using LabVIEW PDA 8.2.1 along with the corresponding NI
Suite.

I'm trying to use the PDA Module to send data packets via an RS232
Serial cable to an external device that will accordingly deal with
those packets and in some cases respond.

As it is, I've developed an application that functions perfectly on my
desktop computer alone, sending the correct data as I would like. I
can even get the PDA to read the data that it sends when it is
connected to the receiving side of the cable.

My problem occurs when I try to use the PDA to send the data to the
desktop via the same application. I can retreive the data I need
within the program; it is when I try to write via serial interface
that I am given the error code -1073807343, which according to NI
support is "Insufficient location information or the device or
resource is not present in the system."

I have been able to write via RS232 with the PDA directly from a text
file in a separate VI before, which I modified for the current app
although an older build still remains on the PDA. This older build
functions perfectly, something I am inclined to believe occurs simply
because it does not call any subVIs.

My current code reads data from a text file, modifies it, then
converts the data into a byte array and finally a string which it
should write to the Serial port. Everything looks ok when I am
probing in my desktop, which makes sense because everything functions
on the desktop. In the past I have had issues with subVIs on the PDA
and have solved them by allowing the PDA to open the front panel for
each new subVI that is called, although I believed this to only be
necessary when graphs or picture controls were present, something that
does not occur in any of my VIs.

My call of the VISA Write function occurs within a subVI, and this is
also where the error message appears. Is it possible that my app is
"forgetting" that I configured the VISA access because that
configuration is not occurring in the top-level VI?

I am sorry to say I cannot post my program, although I would be happy
to respond to any questions as to how the dataflow occurs.

[Brian_R]

As long as you wire the VISA reference out from the VISA Configure Serial Port.vi, you should be to pass that reference anywhere in your program and use that for serial communication.  You can configure the serial port in a sub-VI as long as you pass the reference out of the VI to the top level VI.  By the description of that error, I would check the error output after calling VISA Configure Serial Port.vi to see if you get an error configuring the serial port.