GPS Tracking with the Garmin 60C Series

The M7 GX series of GPS transponders may be directly connected to a Garmin 60C series of hand-held GPSs.  All members of the Garmin 60C family have an RS232 option that is compatible with NMEA 0183 messages.  This allows them to be used with Raveon’s RavTrack series of GPS radio transponders to make a complete GPS tracking system.

When connected to the M7 GPS radio transponder or the Atlas PLPersonal Locator, the Garmin’s map will show the location of all of the the user PLUS the location of all other transponders within radio range.  This unique feature allows one to quickly, easily, and inexpensively, make a portable AVL system for tracking cars, trucks, racecars, construction equipment, or any thing Raveon’s M7 GX or Atlas PL transponder may be installed on.

The Garmin 60C series of hand-held GPSs have built-in interfaces for a “NMEA 0183″ devices, which is another way of saying that they can connect to other devices using a serial cable.   The NMEA 0183 is an RS232 serial connection that typically operates at 4800 baud.  It is used to exchange way-point and other information between displays, GPS devices, and transponders.

When Raveon’s M7 GX transponder is connected to the Garmin display using the NMEA 0183 connection, the GPS radio transponder can put icons on the screen of the Garmin display.  As the transponder receives updated positions from other vehicles, it updates the position of the tracked vehicle icons on the Garmin’s display.

Garmin 60C, 60CS, 60Cx Wiring

From the Garmin technical manual, here is how their NMEA 0183 interface works:

NMEA 0183 Cable Connections

NMEA 0183 is a standard communications format for marine electronic equipment. For example, an autopilot can connect to the NMEA interface on the Garmin 60C and receive positioning information.  The Garmin 60C series can exchange information with any device that transmits or receives NMEA 0183 data.  See the following diagram for general wiring connections. Read yourother product’s owner’s manual for more wiring information.

NMEA 0183 Wiring  (Data cable)

Wiring the Serial Cable

The Garmin’s “Data Cable” must be connected to the M7 GPS transponder (or Atlas OL).  This connection will allow the M7 to put icons on the screen of the Garmin display, showing the location of other tracked vehicles.  The Raveon M7 GPS transponder uses a 9-pin “DB9″ connector to connect to the Garmin.  Solder the Garmin data cable wires onto a DB9 connector and plug the DB9 into the M7 transponder as shown below:

Connect the white wire(serial data from M7 into Garmin) from the Garmin’s Serial Cable goes to pin 2 of the M7′s RS232 DB9 connector.  You do not need to connect the brown wire(serial data from Garmin), so you can trim it off.  Connect the shield braid of the Garmin Serial Cable to pin 5 of the DB9.  The red wire optionally can connect to pin 9 of the Raveon GPS transponder’s DB9 to power the Garmin from the DC source that powers the M7.

If you do not wire your own cable, but instead use Garmin’s RS232 serial cable, you will need to connect the Garmin’s RS232 cable to the M7 GPS transponder using a “NULL Modem” adaptor.

Configuring the Garmin

Set the NMEA communication of the Garmin to 4800 baud.

Configuring the M7 GX Transponder

Raveon has a designed the M7 GX transponder to work with Lowrance Display or any other NMEA 0183 display that can accept the “$GPWPL” NMEA message.   The $GPWPL is an industry standard message that the Lowrance displays and many other GPS displays interpret as a waypoint command.  The M7 GX outputs this $GPWPL message to put icons on the screen of the Lowarance, and to move the icons around on its screen.

To configure the M7 transponder to output the $GPWPL message, set the M7 GX to GPS mode 2.  To do this, put it into the configuration mode by send the +++ into the serial port.  The M7 will respond with an OK.  Type GPS 4 and press enter to put it into GPS 4 mode.  GPS 4 is the mode that causes the M7 GX to output $GPWPL messages whenever it receives a status/position message over the air.