i have a strange problem in using the javax.comm api.
The serial port could be opend without any problems (usb to serial-adapter), switching ports manually is also no problem.
Now two lines from an external machine are connected to this usb adapter. The external machine switches line 1 to high, line 2 to high, waits a short time, switches line 1 to low, line 2 to low and so on.
During this time i can see on the oscilloscope, that if line 2 is high, line 1 is also high, without any doubt, no errors from outside, the voltage levels are really okay.
Now i try to read these signals on the machine, that uses the usb adapter and javax comm, but i have the problem, that if i let run a program, that only prints out the state of line 1 and line 2, i really get the state, that line 2 has another level than line 1.
A interface expects a minimal protocol implementation. 0 So for example a serial port, the hardware itself, expects a certain rate at which high/lows arrive. If the signal is outside of the expect range then the behavior is indeterminate.
I would expect that is your problem.
And just in case the signals are interpreted digitally, so you are never going to get different 'levels' (if that is what you meant.)