I need a lightweight serial protocol analyzer that will let me see what's happening on an RS-232 line, or at least a terminal program that will let me capture images from a serial stream. I've seen such things pass before my eyes, used by colleagues, but I've never needed one myself.
Any recommendations? I'm running Windows XP, and getting by in Cygwin with cat /dev/ttyS0 > file.txt. It's adequate, but barely.