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Ifinder Com Port


PeterGo2
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Hello Everyone,

 

Other posts on this forum (here and here) have hinted at the tantalizing possiblity of writing waypoint data to Lowrance's budget iFinder Go and Go2 models. A post on another forum (original in German) also appears to confirm this.

 

I bought an iFinder Go2 last August, and I recently purchased a Lowrance serial interface cable and tested several data transfer programs with this unit. You might be interested in what I've been able to glean regarding uploading and downloading waypoint info to/from these units...

 

The iFinder Go and Pro models include a slide-on socket on the bottom of the unit with RS-232 compatible Tx/Rx terminals. Lowrance sells an optional adapter cable (PC-DI5, $34.95) that connects to this socket, with the other end wired to a standard female DB-9 connector (e.g. to attach to a computer's COM port). ADDED: The DB-9 connector on this cable is clamshell-style. Opening with a screwdriver reveals that only pins 2, 3, and 5 (Rx/Tx/Gd) are used. In other words, no handshake looping is implemented.

 

Lowrance's GPS Data Manager V.3.1 ("GDM16") uses the Lowrance Serial Interface Protocol ("LSI 100") to transfer waypoint data to and from older Lowrance GPS models. As far as I can tell, there are no current Lowrance products in the list of supported models for GDM16. This implies that newer Lowrance products do not implement LSI 100, and my own Go2 testing supports this hypothesis. Ron Henderson also confirms this on his G7ToWin web page.

 

For newer Lowrance models that include an MMC slot (such as the iFinder Pro), GPS Data Manager V.6 ("GDM6") can be used to copy data to and from memory cards via the Windows API. But the iFinder Go models do not include a memory card slot...

 

The iFinder product manuals indicate that most models include an implementation of NMEA 0183 version 2.0. NMEA Input and NMEA Output are disabled by default but can be enabled in Advanced Mode via Menu > System Setup > Com Port. The iFinder product manuals (and the Configure NMEA screen on my Go2) list the following selectable sentence identifiers:

 

- GLL (transmits latitude and longitude of present position, time of position fix, and status)

- RMC and RMB (transmits navigation information messages)

- APB (transmits autopilot information)

- GGA (transmits time, position, and fix related data)

- GSA and GSV (transmits fix mode, DOP values, and satellites in view information)

 

These identifiers allow the iFinder to be used as a simple GPS sensor (e.g. connected to a laptop PC with suitable software). I've used a trial version of GPS Express 3.2 from Steelwater Solutions Corporation to verify that my Go2 does support these identifiers.

 

 

(Peter)

Edited by PeterGo2
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OK, sorry for the "possible" false report! Just found this post which indicates that some hard-core users have actually gotten waypoint uploads to work with the iFinder Go models. At this point I don't get it, since there are only seven NMEA sentence identifiers listed in the iFinder interface and manuals, and WPL is not one of them.

 

Per the NMEA 0183 protocol, a device can be a "talker" or a "listener" (or both). Perhaps the list of seven sentence identifiers only applies to the iFinder when operating as a talker?

 

:lol:

Edited by PeterGo2
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OK, more info and understanding on this mostly undocumented feature...

 

NMEA Input and NMEA Output are disabled by default but can be enabled in Advanced Mode via Menu > System Setup > Com Port. The iFinder product manuals (and the Configure NMEA screen on my Go2) list the following selectable sentence identifiers:

 

- GLL (transmits latitude and longitude of present position, time of position fix, and status)

- RMC and RMB (transmits navigation information messages)

- APB (transmits autopilot information)

- GGA (transmits time, position, and fix related data)

- GSA and GSV (transmits fix mode, DOP values, and satellites in view information)

After some experimenting with HyperTerminal it becomes clear that the selectable sentence identifiers in the Configure NMEA screen only apply to the NMEA Output mode. Selected sentences are broadcasted approximately once a second, which makes the iFinder useful as a simple GPS sensor (e.g. connected to a laptop with suitable software). Disabling NMEA Output stops these broadcasts altogether.

 

Enabling NMEA Input allows a valid sentence (i.e. with a properly computed checksum) to be sent to the iFinder. For instance, copying the following string (purloined from the other post):

 

$GPWPL,4147.078,N,11201.768,W,NAME*5D

 

and pasting into the HyperTerminal console via right-click > Paste to Host causes a new waypoint (41°47.078'N 112°01.768'W) named NAME to immediately appear in the list of My Waypoints. You won't receive any feedback in the HyperTerminal console, as the NMEA 0183 protocol doesn't provide for it with these types of sentences.

 

WOW!!! :lol:

 

Per the previously cited protocol document:

 

NMEA 0183 devices are designated as either talkers or listeners (with some devices being both), employing an asynchronous serial interface with the following parameters:

 

Baud rate: 4800

Number of data bits: 8 (bit 7 is 0)

Stop bits: 1 (or more)

Parity: none

Handshake: none

The iFinder defaults to 4800 baud (per the spec), and there are no other parameters that can be selected in the user interface. But HyperTerminal defaults to different settings, and you will need to reset these to match the NMEA 0183 protocol and the iFinder. To do this select Call > Disconnect, then select File > Properties > Connect To > Configure, and make the settings match the quoted parameters.

 

Happy Hunting!

Edited by PeterGo2
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