Kantronics MT1200, Руководство пользователя

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To verify that your serial cable is correctly wired and connected, you need to run or
install communication software in the computer and then use that software to establish
communication with the MT1200.
Cabling an external GPS receiver to an MT1200
NOTE: This section applies to the MT1200 (without internal GPS). It does not apply to
the MT1200G, which comes with a GPS receiver module installed inside.
The NMEA standard specifies that the signals in the GPS receiver data port follow the
EIA-422 standard.
Technical note : Many GPS vendors simply use “TTL” voltage levels (+5 V and 0 V),
but use the same polarity as RS232. These units are capable of driving a Kantronics
TNC RS232 serial data port input pin. However, some GPS vendors invert the sense of
this signal (true TTL), and these units will not directly interface with a TNC.
Warning: The Kantronics TNC serial ports are RS232; that is, they provide for signals
that swing plus and minus approximately 8 V. Check your GPS manual before
connecting this port to your GPS device to make sure that it is capable of handling
these voltages. Kantronics is not responsible for damage wherein its TNCs are attached
to other devices; see the Kantronics Limited Warranty.
To connect the data port of a GPS unit to your TNC, you’ll need a two or three-wire
cable. A shielded cable is preferred. Refer to your GPS manual to determine which pins
are used for signal ground, data output to an RS232 device, and data input from an
RS232 device (such as the TNC). At least two of these wires must be connected at both
ends of the cable:
•
connect the signal ground wire of the GPS data port to pin 5 of the DB9 serial port.
This wire may be identified as “NMEA-” by some GPS vendors.
•
connect the “data output pin” of the GPS data port to pin 3 of the DB9 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.
•
Enable GPS input to the DB9 serial port by setting ABAUD in the MT1200 to match
the baud of data output from your GPS receiver, then set INTFACE to GPS.
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 2 of the DB9 serial
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