Connecting M7 to Garmin Oregon


The M7 GX series of GPS transponders may be directly connected to a Garmin Oregon 450. When connected, the Garmin display map will show the location of the vehicle it is in PLUS the location of all other M7 transponders within radio range.  This unique feature allows one to quickly, easily, and inexpensively, make a mobile AVL system for tracking cars, trucks, race cars, construction equipment, or any thing Raveon’s M7 GX transponder may be installed on.

The Garmin Oregon 450 has a 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 Oregon using the NMEA 0183 connection, the M7 transponder can put icons on the screen of the Garmin display.  As the transponder received updated positions from other vehicles, it updates the position of the icons on the Garmin display.

How NMEA 0183 works

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 of a GPS and receive positioning information.  The GPS can exchange information with any device that transmits or receives NMEA 0183 data. See the following diagram for general wiring connections. Read your product’s owner’s manual for specific wiring information.

NMEA 0183 Wiring  (Data cable)

The Garmin Oregon 450 uses the yellow wire to transmit, the white wire to receive and the Black and green wire for ground.

The M7 DB9 Serial Connector

The 9-pin serial I/O connector on the M7 is a female 9-p D-sub miniature connector having the following pins configuration.

Front-view of DB-9 connector on modem (female)

Pin # Name Dir Function Level / Specification
1 CD out Carrier detect
2 RxD out Receive data Data out of the modem.
3 TxD in Transmit data Data into the modem.
4 DTR in Data terminal ready Normally ignored by the FireLine modem.
5 GND Ground connection Signal and power ground
6 DSR out Data Set Ready
7 RTS in Request to send
8 CTS out Clear to send
9 Power In/out DC power (not Ring signal) User may supply the DC power to the modem on this pin.

Wiring the DB9

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

The white wire goes to pin two of the DB9, the yellow wire to pin 3, the black and green wires get twisted together and both go to pin 5, and the red wire goes to pin 9 of the DB9. It is recommended that you keep the fuse on the red wire when setting up the DB9 connector.

Configuring the M7 GX Transponder

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

Raveon Technologies Corporation

990 Park Center Drive, C

Vista, CA 92081