USB to RS232 converter problem (prolific chip)

[Andrei Kolu]

Hello.

I have problems using USB to RS232  converter under FreeBSD 6.3-STABLE when 
connecting to any Cisco gear over serial link. I connect my adapter to 
notebook and dmesg output looks like this one:

ucom0: Prolific Technology Inc. USB-Serial Controller D, rev 1.10/4.00, addr 2

I have also following modules loaded:

 8    1 0xc0c17000 3540     umodem.ko# cu -l /dev/ttyU0
Connected

 9    4 0xc0c1b000 3208     ucom.ko
10    1 0xc0c1f000 2f54     uplcom.ko
13    1 0xc0c2f000 3384     ubsa.ko

Now I try to connect to Cisco box:

# cu -l /dev/ttyU0
Connected

And terminal stalls- nothing happens- it ignores keyboard completely- 
sometimes it works but then suddenly lost keyboard interactivity. I tried 
from KDE Konsole, from plain tcsh command line, sometimes I am able to gain 
Cisco command line but 90% of times it just hangs. I got two usb2serial 
adapters: Trendnet TU-S9 and Manhattan 205146. Same converters works just 
fine under Windows and Linux (drivers cd even got RedHat 7, 8 and 9 versions 
source code drivers- 
http://www.manhattan-products.com/driver-usb-rs232.shtml).