Re: Elusive Serial Cable/Plug

Todd Inch (starnet!apple!mav.com!toddi)
Tue, 26 Jan 93 13:44 PST

Well, I started to write it down, but then I found that the two cables I'd
bought at the same time from the same vendor had different internal color
codes.

What I did was use the mini-din to db-25 adapter and a continuity tester to
find out what the DB-25 pins mapped to. Then, to loopback the hardware
handshaking and pass only the data leads, I connected the (DB25 pin numbers)
4 and 5 together, 6, 8, and 20 together (but separate from 4 & 5) and
connected pins 2 and 3, transmit and receive data or vice versa, to the
red and green (center two pins) on the RJ11 jack. Pin 7 I connected to
both the yellow and black (outer two pins) on the RJ11. If my transmit/
receive are reversed, I just use a straight wired RJ coupler plus a
cross-wired cable to reverse, or cut the plug off and crimp on a new one
facing the other way.

If you don't have your DB25 adapter cable or a continuity tester, I could
drag mine out and tell you which pins are which if you like.

So did I answer your question or give you more questions?

Oh, I forgot to say that the DB-25 pin 1, protective ground, and
Ring Detect (Pin twenty-something) I left disconnected.

Someone did say, I recall, that the DB25 adapter does not give you the
equivalent of a PC port since it has a built-in cross, which I'm not
sure of but isn't applicable with my RJ-11 style wiring.

I can check all this out if you like, however, since I do have a breakout
box and am supposed to understand all the hardware handshaking even though
I choose to use it as little as possible :-).