Anne Wilson wrote: > > I'm not often beaten by things, but sometimes I have to fight them on and off > for quite a while before they are resolved. I'm grateful for all the help I'm > getting here. I shan't be giving up for a good while yet :-) if at all. > > Anne RS232C is enough to kick anyone's butt. For openers, the RS232C "standard" has been bent more ways than any other so-called standard I've ever worked with. I would never attack a situation such as you have (nothing given, find everything and prove 3 ways) without a breakout box. Lacking one of those, you might find the statserial program to be of some use in figuring out what the control lines are doing. # yum --enablerepo=dag install statserial will install it. It has a short man page. Run with no options except device ( # statserial /dev/ttyS0 ) will cause it to loop, indicating status of all control signals. You can manually tweak any of the pins with direction of "in" with a 9-volt battery or by using a paper-clip jumper from one of the "out" lines. It won't be long before you can identify the port, moving an "unknown" to "found". Good luck!