Hi All,
I am a begineer in Linux, I have 4 ports and 3 are operational port 1,port 2 and port 4 (when I plug in serial device I can see it working) but port 3 seems it is not working.
I am sure the hardware is fine.

when I give command

dmesg | grep tty

I get,
serial 8250:ttyS0 at I/O 0x3f8 (irq=4)is a 16550A
serial 8250:ttyS1 at I/O 0x2f8 (irq=3)is a 16550A
serial 8250:ttyS2 at I/O 0x3e8 (irq=4)is a 16550A
serial 8250:ttyS3 at I/O 0x2e8 (irq=3)is a 16550A
0:05:ttyS0 at I/O 0x3f8 (irq=4) is a 16550A
0:06:ttyS1 at I/O 0x2f8 (irq=3) is a 16550A
0:09:ttyS3 at I/O 0x2e8 (irq=11) is a 16550A

I also tried setserial -g /dev/ttyS2 but getting the same result

My Qustion is:
1) what is the difference b/w first 4 lines and last three lines and Y is port 3(ttyS2) not getting displayed in b/w last three lines.
2) Is there something I have to do to enable port 3.
2)Please help me out to get the port 3 into working condition


Thanks in advance