Kantronics KPC–3 Plus User Manual page 93

connect the ―data output pin‖ of the GPS data port to pin 2 of the TNC serial port.
The data output pin may be identified as ―NMEA+‖ by some GPS vendors; this is
the line that supplies the NMEA sentences to your TNC.
Some GPS units may allow for programming of parameters. If so, this is accomplished
by passing commands to the GPS unit from a terminal (or TNC) via an additional pin in
the data port.
If your GPS unit accepts the setting of parameters, you may wish to connect the third
wire of your cable from the input data pin of the GPS data port to pin 3 of the TNC serial
port. Again, consult your GPS manual for the name of this pin; names vary by vendor.
Also, make sure this pin will accept an RS232 signal (+ and – voltages).
Alternate GPS Input
In the KPC–3 Plus, an alternate input for GPS data was added in firmware version 8.3.
This input is pin 2 on the KPC–3 Plus' ―Radio‖ port, and is enabled with the KPC
command GPSPORT. A data signal ground is also required, which is pin 6 on the
―Radio‖ port connector, or pin 9 (if internal jumpers are set to configure pin 9 as a
ground connection).
Note: The default function for pin 2 on the KPC radio port is XCD (external carrier
detect). If pin 2 on the KPC radio port has been connected to a GPS device, and
GPSPORT has been configured for GPS input on this pin, the XCD function is not
available.
Configuring a Kantronics TNC for GPS Operation
To configure your Kantronics TNC in GPS Mode you must set several command
parameters from your PC keyboard as follows:
select the GPS strings you will be capturing in each of the Location Text buffers
set the beacon rates for each Location Text buffer you are using
enter the unproto paths for each Location Text buffer you are using
You determine which GPS strings will be stored in the Location Text (LT) buffers by
entering the string header with the GPSHEAD command. The TNC searches for specific
strings of data from the GPS unit and stores them in up to four LT buffers. These LT
buffers may then be transmitted at periodic intervals as a beacon. The frequency of the
beacons is controlled independently for each LT buffer, by the BLT command (which
stands for Beacon Location Text). You may also set the destination address and the
path for each of the four LT beacons independently using the Location Text Path (LTP)
command.
If the GPSHEAD string for any LT buffer is empty, that LT buffer can be set up as an
auxiliary beacon; LT, BLT, and LTP are used like BTEXT, BEACON, and
UNPROTO.
93