[GreenKeys] Teletype 3320

[Chris Elmquist]

Nico,

I apologize.  I got the RS232 signaling backwards.  See below.

On Sunday (03/07/2010 at 07:59AM -0600), Chris Elmquist wrote:
> 
> > - is this a straight RS232 machine, or do I need a 20 mA current source
> 
> Pins 2, 3 and 7 sure suggest to me that it is straight RS232.
> 
> The TTY will transmit on pin 2, receive on pin 3 and 7 is ground.

Wrong.  I gave you the DCE (aka, modem end of the connection).  I believe
(now), that the TTY will transmit on pin 3 and receive on pin 2.

> You might try hooking the TTY to a PC using only pins 2, 3 and 7 and
> then see if you can communicate with it using a terminal emulator, while
> just leaving pins 24 and 25 open.

The TTY and the PC are both DTE.  So, they transmit and receive on the
same pins.  Therefore, you will need a null modem / cross-over cable to
connect them together.  Hook 2 to 3 and 3 to 2 and 7 on the TTY to 5 on
the PC's DB9.  eg,

	TTY	PC

	2	3
	3	2
	7	5

Sorry about the initial confusion.  Inspite of having worked on RS232
multi-port serial cards, modems and terminal equipment for most of
my life...  I still get it backwards.  Geesh.

Chris
-- 
Chris Elmquist