I'm using the PalmConnect USB->Serial because I don't have a serial/lpt port. It works fine with others devices (like Palm's and PIC programmers) but when I try to use it with LCDSmartie (matrix.dll COM3 (ya, it COM3 for sure ) it got an error: 'Failed to open device: DLL Initialize error: MATRIX.DLL Exception: The handle is invalid (or The input/entry is invalid, it's in Dutch over here )'! I tried different DLL's, reinstalling my PalmConnect and switching it to another COM-number but without any succes :S
Can you try this version: http://czi.uni.cc/LCDSmartie/matrix.dll
and see if it works for you?
I think it's the Dutch Windows, the "dot" [.] is used instead of the "comma" [,]
I checked the values with a volt-meter with the GND to the most left pin (seen from the bottom of a female DB-9) and the other to the middle pin (3) and the values shifted from -5B to -10V so I think it's working
Do you by any chance have other programs trying to use the same COM port?
Another possibility is that your USB-serial adapter is not providing a real serial port emulation. FTDI especially and some prolific adapters are known to work well.
I'm using my hobby-pc right now, which has a build-in serial-port. It read voltages between 0 and -15V but when I read the voltages from the LCD, I got just 0.0V except for the unused ports :S