[aprssig] KPC3+ induced errors

Stephen H. Smith wa8lmf2 at aol.com
Tue Mar 15 17:54:03 EDT 2011

On 3/15/2011 2:17 PM, Max Harper wrote:
>  You must let them know just how bad this problems is. Send any information 
> you have to
> service at kantronics.com <mailto:service at kantronics.com> even if it is just to 
> say that you are experencing the delay problem but don't have any other info. 
> I am just one voice here. I could not answer their question about 
> transmitting and receiving or just receiving.
> Max
> --------------------------------------------------------------------------------------------------------------------------------
> Max:
> I have forwarded a copy of your message to our code programmer, when I
> received your message last week. I have not heard back from him as yet.
> No one has reported having any problems in KISS mode in the KPC-3 Plus,
> anytime recently (in the last few years).
> Are the KPCs used in KISS mode only receiving, or both transmitting and
> receiving?
> Ken
> Kantronics Technical Service

The KPC3+ TNCs in question are being used as APRS internet gateways and/or 
digipeaters implemented with programs running on external computers (i.e. not 
using the internal KPC3+ firmware digi function).

The problem appears after several hours or day running in KISS mode and shows 
up as RECEIVED packets being held for long periods (up to several minutes at 
times) before being passed out the serial port to the attached computer.  The 
TNCs in question are being used for both transmit and receive, but the problem 
is on the receive side.

The problem does not appear when the KPC3+ is used as a stand-alone 
firmware-based digi, or in conventional command line mode.  (The problem only 
shows up when operating in KISS mode.)

It does NOT appear in KISS mode with the earlier original (non "plus") version 
of the KPC3.

The problem is showing up on both various flavors of Windows-based systems with 
programs such as Uiveiw and APRSisce, and on Linux-based systems running Xastir 
so it appears NOT to have anything to do with the way computer OSs are dealing 
with serial ports, etc.

Here is another post on the issue from the  CA_APRS Internet mailing list:


From:  alan at spamcop.net
Subject: [ca_aprs] Re: New poll for ca_aprs

Attached is a post I made today on Lynn's APRSIS32 group:

I have been testing several KPC-3+'s trying to duplicate the known 3+ APRS I-Gate delay problem. N6VUD-2 I-Gate finally started delaying packets to IS. This happened after letting it run without any interruptions for about 5 days. It started delaying packets by about 2 minutes, after a few days up over 10 minutes. I have documented my findings, and it appears to be a buffer holding back in the 3+. I tested with APRSIS32 running AGW and the 3+ in KISS. Somehow the 3+ starts to buffer packets, probably within the MC68HC11F1 processor, since it was holding back over 50 packets. It then starts sending old stale packets as new packets were received in a FIFO fashion. I have a video of this, I will post it.

After documenting I wanted to see if a simple exit KISS, enter KISS from the Enables/Ports/KPC3+ would clear the delay. After un-checking the KPC-3+, then checking again It did clear up the delay problem.

Could a timed port reset macro be added? I would like to be able to have it exit KISS, then re-start KISS immediately. This could be done late at night, or every six hours.

I have been working with another I-Gate sysop that has the same problem, he is running javAPRSIGate, and has a timer that resets the power to the KPC-3+ every morning 5AM. It clears the delay, but sometimes starts delaying again after as little as 4 hours.




Stephen H. Smith    wa8lmf (at) aol.com
EchoLink Node:      WA8LMF  or 14400    [Think bottom of the 2M band]
Skype:        WA8LMF
Home Page:          http://wa8lmf.net

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