Problems addressing the serial port

donwny · 05-25-2011, 09:16 AM

First of all let me introduce myself, I'm a retired (from work not Linux) user of Linux. I'm not a developer or programmer just a user.
I'm trying to install a packet radio system using Linux. The TNC is a Kantronics KPC3.
The issue I'm having is the communications programs I have tried (minicom and cutecom) do not talk to the TNC.
I'm using a computer that has a serial port and it is enabled in the BIOS.
I have added myself to the uucp group in an effort resolve this issue.
Any help would be greatly appreciated.

fishlike interliners · 05-25-2011, 09:40 AM

Quote:

I have added myself to the uucp group in an effort resolve this issue.

Nearly there I reckon. Just make sure that you have added yourself to the correct group. E.g., on this system:

Code:

$ ls -l /dev/ttyUSB0 
crw-rw---- 1 root dialout 188, 0 May 21 14:15 /dev/ttyUSB0

...dialout would be the correct group to add yourself to.

The other thing is minicom's user interface can be a bit idiosyncratic. Make sure you are asking it to do what you think you are asking it to do. Also try as root see if anything works, and try with a known-good device at the other end of the serial line see if you get any comms.

donwny · 05-25-2011, 09:40 AM

Forgot to add, system is Debian 64 bit.

donwny · 05-25-2011, 09:49 AM

Thank you for the quick response, here is the result of the command you mentioned:
ls -l /dev/ttyUSB0
cannot access /dev/ttyUSB0: No such file or directory

michaelk · 05-25-2011, 10:17 AM

Have you used the TNC before i.e the default baud rate has previously been configured? If so then the autobaud rate value should be stored so make sure that minicom is configured to match.

Are you using the correct RS-232 cable? Should be a straight through cable i.e. not null modem.

Look at the manual on page 38 to make sure minicom is configured correctly. Flow control should be on.

donwny · 05-26-2011, 07:06 AM

Thank you for the suggestions, they proved invaluable.
Have the TNC talking to the communications program now and the rest of the issues appear to be with the TNC.
Thanks again for the help

michaelk · 05-26-2011, 07:54 AM

Thanks for the update.

BTW /dev/ttyUSB0 was just an example to show device permissions. ttyUSB0 is a USB serial port adapter device ID. Since you are not using one the device will not exist on your system. Legacy hardware serial ports are /dev/ttyS[0-3].