Difference between revisions of "Garmin FMI"

Latest revision as of 15:08, 11 April 2016

Garmin's Fleet Management Interface is used by the Tracker2 and the GTRANS cable. At least two different connector types are in use by current Garmin models - a USB mini-B type and an 18-pin Hirose ST series connector. The official FMI specification does not include waypoint creation, but it does work on some models. However, most models create duplicate waypoints for a moving station, rather that simply moving the existing waypoint.

For Garmin's FMI FAQ, visit http://www8.garmin.com/solutions/mobile-resource-management/supported-devices/.

FMI Introduction

Choosing the Right Cable

NMEA 0183 is the standard used by most GPS receivers to send data, including position, velocity, time, and signal quality information. Most of Garmin's chart plotters, OEM sensors, and older handheld devices have an NMEA output, usually through a proprietary 4-pin connector. Many of their USB-capable devices, on the other hand, have no NMEA output at all and can interface only with a USB host - usually a PC.

To address the needs of commercial fleet operators, Garmin added the Fleet Management Interface (FMI) to some of their automotive products. FMI does not use NMEA, but it does provide a serial interface - usually through the USB connector - that can be used by some devices. Our Tracker2 and Tracker3 series have FMI support and as such only need an appropriate FMI cable. Garmin maintains a list of FMI compatible devices and which cable they require - see the FAQ link above.

Devices expecting NMEA data, like the Kenwood TM-D710 and TH-D72, can not use FMI directly. However, our GTRANS product serves as a protocol translator and will convert between FMI and NMEA. Our regular GTRANS series takes the place of the Garmin 010-10813-00 FMI cable and connects directly to the Kenwood radios, Yaesu FTM-350, Uniden Home Patrol 1, and other NMEA devices. The GTRANS2 series takes the place of the Garmin 010-11232-10 (FMI 15) cable.

Additionally, some of Garmin's newer handheld GPS receivers have only a USB connector, but can put out NMEA data using the Garmin 010-11131-00 cable. This is not an FMI cable or a protocol translator. It's a simple voltage level converter and the NMEA functions are handled by the GPS receiver itself. With the proper connector, this cable can be connected to most APRS-capable radios and trackers.

Technical Details

FMI is built on top of Garmin's older proprietary serial interface protocol. Like the old protocol, it runs at 9600 baud. All FMI packets are encapsulated within the old protocol. However, some of the legacy protocol's functions are also supported by FMI-capable devices. This includes the PVT (position, velocity, and time) mesage. PVT can be enabled independently of the FMI functions. Also, some of the earlier FMI-capable devices also supported (possibly by accident) the old waypoint creation protocol. It's this protocol that the Tracker2 and Tracker3 devices use to plot stations on the map.

The physical interface is through a USB mini-B connector on most devices. The ID pin is used to identify the cable connected, using a resistor in the FMI cable's connector. For the 010-10813-00 cable this is an 8.2k ohm resistor to ground. In the FMI 15 cable it's 12k. The 010-10813-00 cable contains an inverter and RS-232 transceiver that adapts the low-voltage signals to RS-232 levels and polarity. The FMI 15 cable also includes a DC-DC converter to provide 5v power to the GPS unit.

The GTRANS cable, when used with FMI 2.0 and earlier devices, does not place the attached device into FMI mode. This avoids changing the menn layout of the device. For FMI 2.5 and above, however, the newer FMI-based waypoint creation protocol is used, and this requires placing the device into FMI mode.

Comment Text

Not all Nuvis will display the comment text from APRS packets. The Nuvi 350 properly displays comments, when viewing stations from the Favorites listing.

Other Nuvis do not, for example the 680 does not display comment or status text at all. APRS objects show up as favorites, but with none of the comment or status text.

Information on other Garmin models should be added to this table.

Connectors

Mini-B

The USB Mini-B 010-10813-00 cable uses an 8.2k ohm resistor to ground on the ID pin to identify an FMI cable. The 010-11232-00 cable uses an approximately 12k ohm resistor. Serial signals are 9600 baud, 0-3.3v, inverted (0v = 1, 3.3v = 0).

18-Pin

The 18-pin FMI connector is a Hirose ST40X-18S-CV.

Numbering is per Hirose data sheet. On the wiring side, odd numbered pins are on the top row and even numbered pins on the bottom row.

Please note that this information is preliminary and may be incomplete or inaccurate! The pinouts above were determined by disassembly of a Garmin 010-10865-00 cable and have not been tested.