gtkterm error

Yes, “Sid”. I am using a null-modem cable. Thanks for your reply. What should i do?

That is an error I have never seen.
Make sure the port is correctly set up, e.g /dev/ttyS0 for a normal serial port connection, /dev/ttyUSB0 for a USB serial port.
Speed 115200
Parity none
Bits 8
Stopbits 1
Flow control none
End of line delay (milliseconds) 0

Hope this helps.