I've joined the reverse engineering community to do exactly that - well... later, hopefully. Right now I'm unfortunatly stuck in an earlier stage. I am trying to listen to a modem talking to a controlling software (working on MS DOS) and the other way round - to figure out what this software sends and receives.I am using a python script (module pyserial) to receive the data via a Serial-to-USB adapter. My script should be okay, I tested it with virtual serial ports (software com0com). Well, should be, although I'm not sure, because I don't know what data format I will receive.The modem has two serial ports(25 pin RS242). One is reserved for the connection to the computer running the controlling software on MS DOS, the other one was believed (not supposed, nobody knows anything) to be outputting the same communication parallel to the other port, so I tried to listen to it, but I received nothing (also the software seems to be protesting when I plug in the serial cable connected to my own computer, which is supposed to listen).The computer with the controlling software does have a second serial port. But there is no way setting the incoming/outgoing communications the same as for the other port, is there?So I was thinking to solder kind of a t-junction for the computer<->modem serial cable to connect my own computer for listening. My question is: can this work or am I thinking too simple? My fear is that e.g. the voltage will be cut in half for each connection and therefore nothing will work anymore.Can anyone give me some advice? Thanks in advance! Cheers, Tobi
Sniffing on a serial port through a separate computer
python;serial communication