Could you run the following command:
New error: Cannot not set serial port speed to 19200. Input/Output error. I get this with ttyS0 and ttyS1.
dmesg | grep ttySIf this doesn't work try
sudo grep ttyS /var/log/kern.logYou should then see something like this:
[ 0.218044] 00:02: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A [ 0.218836] ttyS4: detected caps 00000700 should be 00000500 [ 0.218839] 0000:05:00.0: ttyS4 at I/O 0xd000 (irq = 20, base_baud = 921600) is a 16C950/954 [ 0.218965] ttyS5: detected caps 00000700 should be 00000500 [ 0.218968] 0000:05:00.0: ttyS5 at I/O 0xd100 (irq = 20, base_baud = 921600) is a 16C950/954 [ 21.974463] 0000:05:01.0: ttyS6 at I/O 0xd800 (irq = 19, base_baud = 115200) is a 16550A [ 21.994939] 0000:05:01.0: ttyS7 at I/O 0xd900 (irq = 19, base_baud = 115200) is a 16550AThe "ttySx" are the device nodes under dev, the output above is from my Debian PC with one onboard RS232 interface (/dev/ttyS0) and 2 2-port serial cards - an Oxford 16C950 based card (/dev/ttyS4 and /dev/ttyS5) and an el-cheapo NetMos based card (/dev/ttyS6 and /dev/ttyS7).
Addon cards usually get numbers 4 and up, onboard ports have numbers 0-3.