Originally Posted by Larry

T-ROY wrote in news:T-
:

This is very good information. I recently purchased a Icom M422 and
trying to iinterface with a Garmin 178C. The same problems spec was
having are identical to the problems I'm having. I have my MMSI number
in tried several ways to wire it with no success. I to was on the phone
with Garmin and Icom and they suggested all the ways I have tried. Can
someone out there post there solution that is working.



http://www.garmin.com/manuals/494_OwnersManual.pdf
On page 96 of the Garmin 178C owner's manual, notice there are TWO data
channels in this unit Comm 1 and Comm 2. TX Comm 1 is, indeed, the blue
wire and TX Comm 2 is the green wire in the cable. Black is,
unfortunately, DC and data ground, same as my 185S.

On page 86-87, open MAIN MENU then COMM TAB and set the Garmin for NMEA
IN/OUT, not the proprietary Garmin data. If you don't have other Garmin
devices to talk to, set both ports for NMEA IN/OUT to avoid this nonsense
in the future. Notice how the bottom of page 87 says:

"You may also adjust the NMEA output to enable/disable certain sentences
and adjust the number of
Lat/Lon output precision digits. You must have one of the ports set to
NMEA In/NMEA Out to use this
option. Settings affects both Port 1 and Port 2 NMEA outputs."

This means the NMEA statements can be shut off individually in the menus.
Garmin's manual sucks explaining this, as usual, because they want you to
get your Garmin DEALER to install it to make him happy. Hold that
thought and let's go look at the Icom manual.......

http://icomamerica.com/products/marine/m422/specs.asp
"NMEA In/out formats : RMC, CGA, GNS, GLL"
These are the statements the new radio is looking for, well, the last 3
letters of the statements, anyways.....

http://icomamerica.com/support/manuals/m422_manual.pdf
On page 35, NMEA IN is the RED lead (again black is ground, damn them.)
So, we'll hook the BLUE lead from Comm 1 of the Garmin to the RED lead
NMEA IN on the Icom. While we're here and have this nice Chart Plotter
Garmin, let's hook NMEA OUT (the white lead) on the ICOM to the Comm 1
NMEA IN (the brown wire) on the Garmin cable. This SHOULD, but may not,
allow us to automatically plot any DSC distress calls the ICOM receives
on Channel 70..directly on the Garmin charts.

The Icom sends out DSC and DSE statements to the Garmin. But, on page 96
of the Garmin manual, there is no reference to DSC or DSE statements on
the list, there. However, back on page 81 you turn ON the DSC charting
function from MAIN MENU then DSC tab. Turn the DSC to ON, which should
make it read one of these DSC/DSE statements and do "something" the
damned manual doesn't really say what, which isn't new. Don't worry
about MMSI in the Garmin. You can play with that some other time. We
want it to plot ALL stations, not just one.

OK, so the Garmin Comm 1 should be now hooked to the Icom NMEA wires with
a common black wire between them (not depending on the battery wires,
please!)....

Power on the GARMIN and let it sync to the birds. While it's got you
waiting, check the NMEA output statement list and make sure statements
GPRMC, GPCGA, GPGNS and GPGLL are active, not disabled. As there is no
settable speed on these ports any more, we'll assume they are 4800 baud,
n/8/1 and auto setting. It's about time.

Ok, Garmin has a fix, turn on the ICOM with all fingers crossed. Does
the lat/long from the Garmin show up on the Icom display? No? Of course
it doesn't! This Icom HAS NO LAT/LONG DISPLAY! Look at page 4 of the
Icom manual, bubble number 7 the "GPS" indicator on the display. Is it a
solid GPS? If so, the Icom has a fix. If it's blinking, we have data
coming out of the Garmin, but none of the statements the Icom is looking
for is in the data stream to it, or there's noise/hum/buzz/crap from the
damned unbalanced wiring both these companies are using...damn them
again! That's the ONLY display of GPS information on the M422. It costs
a lot more money, M602, to get that lat/long display. Have one, what a
waste...it's a VHF RADIO. This unit's much better and easier to use. If
there is no little GPS symbol at all, there's no signal at all from the
Garmin...wiring error, shorted wires, defective equipment, etc.... It's
gotta be a steady, non-blinky GPS display.

Ok, once we gots all that workin', get the new Autopilot installed and
we'll hook it to Garmin's Comm 2! No sense leavin' perfectly good wires
just dangling there with no toys attached, right?!

Hope this helped you a little better....All this crap needs a good
Ethernet jack on it plugged into a router you can get at any Circuit City
for $60. Then, the radio would KNOW who the GPS, Chartplotter, Autopilot
and other gadgets was from their BROADCASTS and the router could easily
route like a little LAN as it should....not this wrappin wires together
crap we're buying now. How awful......

Larry W4CSC
Chief Engineer S/V "Lionheart" - WDB6254
Charleston Harbor
"Don't call me 'Captain'! I'm not to blame!"