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[aprssig] APRS data via perl-to-tnc

Lee Bengston lee.bengston at gmail.com
Wed Nov 23 19:48:01 UTC 2011


On Sun, Oct 2, 2011 at 11:34 AM, Heikki Hannikainen <hessu at hes.iki.fi> wrote:

> Open the tnc serial device (there's a perl module for that,
> Device::SerialPort, apt-get install libdevice-serialport-perl), read packets
> in, and use http://search.cpan.org/dist/Ham-APRS-FAP/ to decode the APRS
> packets. It contains the kiss_to_tnc2 sub too to decode KISS (although
> you'll have to implement the KISS frame boundary detection yourself).

This came up back in October in a different context.  In my case I'm
just trying to communicate with a TNC using the above perl module, and
if the script sees the cmd prompt, send the commands to put it in KISS
mode.  The problem is that whenever I send "\n" or "\r\n" I am unable
to get the prompt from the TNC, but I can do it manually via minicom
or gtkterm.

The TNC is a Kantronics KPC-9612+.  If I send, for example,
"qwerty\n", all I can capture or receive is the echo of what I sent,
but no expected "EH?" or "cmd:"  If I put the TNC in KISS mode
manually, I am able to send the chr(192) chr(255) chr(192) sequence
using the above perl module and take it out of KISS mode.  It's
notable that no carriage return or newline is required in order to get
out of KISS mode.

Finally, if the TNC happens to be sending packets (while not in KISS
mode) when the script is looking for text, the script can see that.
So it appears that the TNC is not accepting whatever the script sends
as a line terminator.  I thought I would see if anyone on the list has
any experience with Device::SerialPort - maybe this sounds familiar.

Lee - K5DAT



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