Sun serial port communication problem

[Casper H.S. Dik]

quasar at ctt.bellcore.com (Laurence R. Brothers) writes:
>I'm writing a little application to read stuff coming in over my sun's
>serial port (Sun-4/260, though it shouldn't make much difference).
>
>Since I don't yet have the OGM (Obsolete Garbagey Machine) that will be
>supplying the RS232 chatter, I'm faking it by connecting a null modem from
>ttya to ttyb, writing to a, and reading from b.

This is what I think happens:

You write a character to a
It travels to b

It gets echoed by the tty driver at b. (and read by your program)

It travels back to a

It gets echoed by the tty driver listening to port a

It gets back to b. (read again by your program)

... ad infinitum

So switching of echoing on port a and b should do the trick.

This also accounts for doubled line-terminators.  If you output a newline
on port a it gets converted to nl-cr on output.  Port b then finds two
line terminators.

Your best bet is raw & noecho.

Hope this helps,
--cd

Casper H.S. Dik
University of Amsterdam     |		      dik at uva.uucp
The Netherlands             |                 ...!uunet!mcvax!uva!dik