Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!uwm.edu!spool.mu.edu!uunet!mcsun!ukc!axion!delluk!tim From: tim@dell.co.uk (Tim Wright) Newsgroups: comp.unix.sysv386 Subject: Re: SVR4, serial port question Keywords: SVR4, serial Message-ID: Date: 6 Mar 91 11:54:10 GMT References: <1310@h.cs.wvu.wvnet.edu> Sender: usenet@delluk.uucp (Usenet posting login) Organization: Dell Computer Corp., Bracknell, UK Lines: 29 In <1310@h.cs.wvu.wvnet.edu> brian@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@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".