reverse engineering a serial protocol with a scope
I have no idea what you mean by "X" and "Z".

Standard way to reverse engineer an RS-232 signal would be:


Use the oscilloscope to figure out the baud rate. e.g., 0.104 ms pulse width would indicate 9600 baud. (\$ \frac {1}{0.104m} = 9600) \$.
Use the oscilloscope to figure out the number of bits.
Count the bits and see if the last bit changes state to keep the parity even or odd. If you can't see a pattern you can assume no parity bit.
Hook up to a PC running a terminal emulator such as PuTTY.
Set the baud rate to match and try various combinations of parity and stop bits until you start to see sensible data.


That will give you the raw serial data. You now have to figure out what it means.