[Xastir] KAM not transmitting and solution

[Tom Russo]

On Thu, Jul 26, 2012 at 09:33:55AM +0200, we recorded a bogon-computron collision of the <sinageruk at gmail.com> flavor, containing:
> Hi,
> just leaving a quick note on using the Kantronics KAM as a "serial tnc", in
> case anyone else bumps in the same problem.
> 
> Xastir 2.0 as provided by the Ubuntu 11.10 won't work properly, at least
> with my 6.1 firmware.
> 
> My tnc refused to go on tx and a couple of minor fixes in the
> tnc-startup.kam script made no difference (comment "txu on" and change
> "HEADERLN OFF" into "HEADERL OFF", as both commands are wrong).
> 
> At transmission attempts the tnc would reply:
>      $
> EH?
> 
> This post explained the mechanism and pointed me to the right source file:
> http://lists.xastir.org/pipermail/xastir/2009-October/016611.html
> 
> Have a look at line 8667 in interface.c ...and simply do as the source
> says, commenting the line output_net...
> 
>                /* clear this for a TNC */
>                 //output_net[0] = '\0';
> 
> Possibly the Kenwood D700 fix messed up for the KAM.

That comment is not suggesting that the output_net line be commented out,
merely saying that "output_net" should be a null string for a TNC.

The D700 fix didn't impact this line --- it merely added an extra carriage
return to clear the junk out of buffers.

As it turns out, the D700 "EH?" issue is almost certainly due to the "Control-E"
that "Serial TNC with GPS on AUX port" interfaces are sending on the assumption
that all TNCs with attached GPS units require it.  As far as I know, only a
handful actually do, and most these days just pass a mixed feed of NMEA and
AX.25 data automatically.  The EH? on the D700 is almost certainly complaints
about Control-Es left in the buffer.  But anyway, the line you've commented out
has nothing to do with that fix.

Oddly, output_net is not even used in the block of code where it's cleared
out, so it must be getting used elsewhere, and have other stuff stored in it.
I don't know why your commenting this out helped your KAM, but it is NOT
what the comment is telling you to do (it's explaining that it's "clearing this"
variable because we're a TNC not a network interface).

-- 
Tom Russo    KM5VY   SAR502   DM64ux          http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236        http://kevan.org/brain.cgi?DDTNM
"And, isn't sanity really just a one-trick pony anyway? I mean all you get is
 one trick, rational thinking, but when you're good and crazy, oooh, oooh,
 oooh, the sky is the limit!"  --- The Tick