[aprssig] How to send packet through a KISS modem

[Wes Johnston, AI4PX]

I'd have to look to be sure, but the first byte is comprised of a command
and port number.  there are 4 commands... TX (0), txdelay (1),
persistence(2) and slot time (3).  The upper nibble is the port number (or
the upper nibble).  So sending 192,0,<your packet>,192. will make the packet
squirt out port 0.  transmitting 192,16,<your packet>,192 should squirt a
packet out port 1.    Since most TNC's have only one port anyway this is
pretty much a moot point since you'll always use 00 for the two command
nibbles.  Also, most kantronic TNCs have a separate TX delay and slot time
for kiss mode, so you will need to set them if the txd is too long or so
short that your packets aren't decoded.

Also, there is a difference between TAPR 2 and KPC products on the air... I
also can't recall this detail exactly, but something to do with the way
multiple frames are placed into one packet.  One of them adds an extra byte
at the end, the other adds the extra delimiter byte only when necessary.

And finally, you will have to watch the 192 ($c0) appearing in the packet.
You'll have to encode a transposition character.  See
http://www.ka9q.net/papers/kiss.html for the nitty gritty.

Wes
---
Hitler gave great speeches too!


On Mon, Aug 3, 2009 at 10:29, Jason Rausch <jason at ke4nyv.com> wrote:

>
> Rob,
>
> I ran into a few things that kept me from transmitting as well.  One was
> the port byte indicator.  I would have to go back and look at the spec to
> tell you where it goes, but it is one of the first bytes after the first
> FEND.  Also, when you saw "raw packet" wrapped in FENDs, does that mean you
> are not "encoding" it in the correct format?  Just a raw ASCII packet?  If
> you are decoding, then you understand the format that the packet is given to
> you and you must send a packet to the TNC in this same format.
>
> Just for reference, check out the analyzer program I wrote for learning how
> a KISS packet works (its the last program on the page):
>
> http://www.ke4nyv.com/software.htm
>
> Just paste in a raw KISS packet and it will break down every element for
> you.  It is quick and dirty, but it helped me a lot.
>
> Jason KE4NYV
> RPC Electronics
> www.rpc-electronics.com
>
>
> --- On Mon, 8/3/09, Dave Haynes <dave at ep90.com> wrote:
>
> > From: Dave Haynes <dave at ep90.com>
> > Subject: Re: [aprssig] How to send packet through a KISS modem
> > To: "TAPR APRS Mailing List" <aprssig at tapr.org>
> > Date: Monday, August 3, 2009, 4:51 AM
>  > Are you sending the type indicator
> > byte before your packet? After your opening $C0, the first
> > byte indicates the content of the message to the TNC. For a
> > data packet, the indicator byte will usually be $00.
> >
> > All detailed in "The KISS TNC: A simple Host-to-TNC
> > communications protocol" by Mike Chepponis K3MC and Phil
> > Karn, KA9Q
> >
> > Dave
> > G1TVL
> >
> > rfinesmith at aol.com
> > wrote:
> > > Does anyone in the group have experience programming
> > to a KISS modem to transmit?  I have no problem
> > receiving and decoding APRS packets from a TNC in KISS mode
> > (using a my Kantronics KPC3+), but I can't figure out how to
> > get the TNC to send packets while in KISS mode.  I am
> > wrapping my raw AX25 packets in \xC0 prior to writing to the
> > modem, but that doesn't work.  Also, I have tried to
> > manually send text while in kiss mode, using HyperTerminal,
> > also wrapping the text in \xC0 (i.e.,
> > <ALT>-0192).  No luck.
> > >
> > > Thanks,
> > > Robin, AA3NJ
> >
> >
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> >
> >
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> >
>
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