[aprssig] KPC3+ and U800 not talking

n1iic Jason Greene n1iic at arrl.net
Thu Mar 10 19:07:51 CST 2005

Thank you Wes and Bill for the help.

I seem to be doing everything right, I plugged the GPS into the TNC and it
worked for a couple of lines, and that was it. I am suspecting a physical
problem in the interface.
This happens on two different KPC-3's, so that has me baffled.


----- Original Message ----- 
From: "Bill Herrmann" <bherrman at spro.net>
To: "TAPR APRS Mailing List" <aprssig at lists.tapr.org>
Sent: Thursday, March 10, 2005 2:06 AM
Subject: Re: [aprssig] KPC3+ and U800 not talking

> At 08:38 PM 3/8/2005 -0500, n1iic Jason Greene wrote:
> >Greetings, All. I am trying to get my Ultimeter 800 talking with a KPC3+
> >8.3 (and 8.2) and no matter how I configure or connect, I can't get the
> >TNC to hear anything. The  U800 is sending correct data.
> On 8.3 you should be able to use either port. On 8.2 you can only use the
> DB25 port. (The hardware is there, but the firmware doesn't support it
> 8.3.)
> I'm assuming you checked that the U800 is sending $ULTW at 2400bps.
> >I have the GPS string in there for testing, and the GPS didn't work
> >either. It has worrked before, though.
> The GPS is probably sending at 4800bps.
> >Everything is at 2400 baud, and when I connect the Ultimeter to the
> >computer, APRS (or any com program) can see it fine.
> >So, Data is coming out the end of the wire, The computer can see it, now
> The important thing here is where is it coming out. If you can plug the
> cable directly into the computer that means that the cable plus U800 is
> wired as a DCE device. (since the computer is a DTE device)
> >I have tried every possible way to connect the U800 to the TNC, both
> >through pin 2(data) - 6(gnd) on the radio port and both pins 2 and 3
> >(data) and pin 5(gnd) on the DB9 of the DB9/DB25 cable.
> Which pin of what size connector did you wire to pin2 on the radio port?
> (connector size is important here because the meanings of pins 2 & 3 are
> reversed on a 9 pin vs. a 25 pin connector.)
> To plug the U800 into the computer (25 pin) connector you'll have to have
> null-modem adapter or cable between the cable that works with the laptop
> and the TNC.
> To be successful with RS232 you pretty well have to stop and look at how
> the devices are wired (DCE vs DTE) and think about the pin meanings not
> their number especially if you are mixing 9 pin and 25 pin connectors. (I
> mentioned above that 2&3 swap meanings between those. A 9 pin to 25 pin
> cable that swaps the leads between 2&3 is a "straight-through" cable.)
> Bill
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