Hmmm - stubborn problem isn't it.
It seems, from the gpstuner site, that using JAL Port Splitter on a P3300 does allow a .NET based program to read the GPS via the .NET serial port class. If we assume that this is so then there would seem to be no reason why a B4PPC app cannot do the same. As it presently cannot there would seem to be be two areas where the problem could lie.
a) The JAL Port Splitter is not configured properly.
I assume that you have the input port set to COM4 and the virtual output port to something different. GPStuner indicates that COM5 works so I assume you are using that. I don't know what other configuration might be needed
b) The B4PPC app is not using the serial port correctly.
I assume that you have altered the COM port that your app is using to be COM5. Your first post implies that you had a B4PPC program that worked previously before WM6. Have you tried that program with the Port Splitter
exactly as it was before with only the COM port changed? Also have you tried Erels' GPS4PPC unmodified apart from changing the COM port to that of the Splitter?
However at the bottom of this thread where someone has a similar problem
http://www.gpstuner.com/forum/viewtopic.php?t=1201&sid=96e3f7f24e76d645c7139dc7bb5065ef
I found this
Of course, Jaluna also goes on to state that you may need to use the Port Splitter built-in to WinMobile 5.0 and point the two splitters at each other to make the final connection. This does not sound like a fun experiment, and I'm truly sorry you have to jump thru this many hurdles to get the software to work for you...
It doesn't mean anything to me as I have never used WM5 -but maybe WM6 has a similar built-in splitter.
What I don't understand is how your application worked at all under WM5 on a P3300 as all the posts I have found imply that .NET apps won't work. Maybe it was because it was using the old serial library that is not .NET based. In the serial help Erel states that the old libraries don't work under .NET 2.0 yet I thought that WM5 came with .NET 2.0 included. I'm puzzled, any comments Erel?
I'm afraid this is looking like a fundamental problem with the P3300
EDIT:- I've since seen a suggestion, I don't know if it is true, that the P3300 with WM5.0 didn't have .NET installed. Was this so? Did you have to install the Compact framework yourself? If so it must have been .NET 1.0. Does WM6 come with .NET 2.0 in ROM? You could always try installing .NET 1.0 SP3 and go back to the old serial libraries to see if that will work.