SVR4, serial port question

[Tim Wright]

In <1310 at h.cs.wvu.wvnet.edu> brian at cs.wvu.wvnet.edu (Brian Dean) writes:

>I've recently upgraded from SVR3.2 to SVR4.0 (Intel V2.0) and am
>having difficulty getting serial ports to respond to anything.
...
>It seems as though to ports do not respond at all - any attempt at
>connection with "cu" times out with the message "can't access device".
>A short program to access the port (/dev/tty(00 00s, 00h, 01, 01s,
>01h) and /dev/term/(00, 00s, 00h, 01, 01s, 01h)) with the "open"
>system call waits indefinitely for the port to become ready.

Yes, I can tell you what the problem is. You need more than three
wires from the COM port to the device. There is no device provided
which offers "clocal" type behaviour on open(), i.e. all the devices
require DCD high to work. I'm not sure whether this counts as a bug
since I believe it is legitimate (if somewhat stupid) behaviour.
I believe that you should be able to set up uucp to work using the
'\M', '\m' or ',M' options in the configuration files. I haven't tested
this out since I use a multiport card.
If you use your own code, open with O_NDELAY and then use ioctl to
set CLOCAL. I would imagine the ISC will fix this since in ISC's SVR3
products, there you have tty00/ttyd0 etc.

Tim
--
Tim Wright, Dell Computer Corp., Bracknell    |  Domain: tim at dell.co.uk
Berkshire, UK, RG12 1RW. Tel: +44-344-860456  |  Uucp: ...!ukc!delluk!tim
Nobody ever said I was charming before. They said, "Rimmer, you're a total git"
- Red Dwarf, "Camille".