bin/54141: wrong behavour of cu(1)

Eugene Grosbein eugen at
Sat Jul 5 21:30:15 PDT 2003

>Number:         54141
>Category:       bin
>Synopsis:       wrong behavour of cu(1)
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Jul 05 21:30:10 PDT 2003
>Originator:     Eugene Grosbein
>Release:        FreeBSD 4.8-STABLE i386
Svyaz Service JSC
System: FreeBSD 4.8-STABLE FreeBSD 4.8-STABLE #4: Mon May 26 15:07:27 KRAST 2003 root at i386

	cu(1) does not work with some devices connected to serial ports.
	cu -l cuaa1 fails to send or receive a character while
	stock tip(1) or minicom from ports both work nice.

	cu(1) works nice with asyncronous analog modems but does not
	work with some other devices. I have access to couple of such, f.e:

	- Watson IV MSDSL modem and some other DSL modems with serial port
	  (9600, 8-N-1, XON/XOFF)
	- Ericsson MD110 PBX SIU board (2400, 8-N-1, XON/XOFF)

	Sometimes, when I leave cu(1) run connected to a port
	it succeedes to reteive several lines from port but only after
	long run. It seems there is flow control problem, cu(1)
	does not work with devices without hardware flow control.

	Note that tip(1) and minicom use theirs own serial port settins
	for things like parity/flow control while cu(1) relies
	on defaults that can be changed with stty(1).
	Also note that problem devices are low-speed (9600 and slower)
	and do not support flow control. I also have 38400/XON/XOFF devices
	that do not have problems with cu(1).

	Get FreeBSD 4.8 or later (it seems this problem was introduced
	beenween 4.7 and 4.8, but I'm not sure). Get one of mentioned
	devices or try other slow xon/xoff-controlled devices.


	Unknown for me.
	As workaround, I use tip(1) or minicom that work nice
	with all devices I have.


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