as said in http://www.8052.com/forum/read.phtml?id=61022

If it does, you can try and link DSR-pin to DTR pin on the modem side so your modem is "seeing" a terminal connected. Again, the manual of your modem should be able to inform you on the signals needed.

You really should try to understand what these signals are and what they are doing. So check some sites with rs-232 info, there are plenty of sites around. As for the manufacturing of your cable, check http://www.internet-remotecontrol.net/pccompci/...ology.html

the layout you can use to make a cable with only rx/tx/gnd is under the heading "RS232 loop-back test plug for PCCOM Diagnostics". It shows you what you should do with pins other than rx,tx and gnd...


Regards

Patrick