garmin gps 18 pin out help needed

I just got the seriel PC interface version so it has the sub D connector and the 12 V cigarette adapter still attached.

It has no pin out or color coded wire information. No surprise.

If I cut the connectors off to get to bare wire, I'm not sure I'll be able to figure the signal wires later. Anyone done this already and know what signal wire goes to what location on the Horizon and which is the ground?. I already have an external GPS so this would be a secondary GPS source. I'm trying to minimize the wasted time at the airport figuring this by trial and error and would rather get the wires pre terminated before I leave the house so I can get some flying in too to try it out.

thx.

Lucky,

Here's the technical spec for the Garmin 18.

http://www8.garmin.com/manuals/425_TechnicalSpecification.pdf

It has the pinouts, but basically you just need two wires on the d-sub. Pin 3 is data out and pin 5 is GND. I think the cigarette adaptor has a voltage regulator in it that drops the voltage from 12V to 5V. So, I wouldn't just cut that off and attach the wires to 12V. If you can open the adaptor, you should be able to verify whether it's 5V or 12V coming out. I have the 18 OEM and it operates on 5V and I think the pucks are all the same.

Hope that helps,

Chris

This helps for sure! Thanks

A couple more questions.

Do you have to connect to a PC first to change from garmin to nmea format?

Can you get in the puck to remove the magnets or drill them out? They are going to maybe interfere with the compass.

CMW said:

Lucky,

... I think the cigarette adaptor has a voltage regulator in it that drops the voltage from 12V to 5V. So, I wouldn't just cut that off and attach the wires to 12V. If you can open the adaptor, you should be able to verify whether it's 5V or 12V coming out. I have the 18 OEM and it operates on 5V and I think the pucks are all the same.

Chris

Click to expand...

Does anyone know if this is true. I cut off the cig adaptor and wired the hockey puck to my 12v buss. But, I haven't powered it up yet. I looked for the adaptor today to test it and see if it put out 5v or 12v, but couldn't find it. I may have thrown it away.

Thanks,

The GPS-18 is an excellent GPS receiver

... new models have 5Hz o/p and high sensitivity.

The 'PC' version internal voltage is not documented but I would expect the puck is 5V only just like the other models. The conversion is likely done in the 12v cig. lighter plug itself.

Regarding the setup - if it has been used with the Garmin software already you will more than likely have to configure the interface for serial NMEA output and to set the baudrate to match the input of the equipment. Use your PC to do this. These are well documented in the manual - but you might need to get your hands dirty with some software tools to get it the way you want it.

Garmin's own software uses the GPS-18 in binary mode.

Be aware that the serial interface will require Tx and Rx in order to re-configure the unit. Also, while you are at it check the software version and upgrade if Garmin has a new revision available. See Garmin's website for version information.

Confirm the operation is normal on your PC using a terminal emulation software before trying it in your airplane - save yourself the frustration.

Regarding the magnets - I recall someone made mention on the Matronics RV-List some time ago that they had successfully removed the magnets. This person was able to split the unit open around the seam - remove the magnets and glue the unit back together.

I have not done this myself but if you do, can you take some photos and post them here for others to see.

Doug Gray

I've had a GPS-18 installed in the Valkyrie since day one as the "GPS 2" in my GRT system. It has always worked great. A while back, I installed the GRT RAIM GPS module for testing, and simply disabled the GPS 18 serial channel input to the GRT Display Unit, and pretty much forgot about it. Doing some reconfiguration f the system today, I re-enabled the GPS 18 that has been sitting there patiently putting out it's data stream for all that time, and it still works perfectly!

Voltage - yes, the Cig Lighter adapter drops the voltage from 12 volts down to 5 - you'll probably be disappointed if you power it up with 12 volts!

Serial Data - I only have the serial out from the unit connected to the GPS, and it works just fine - it transmits position sentences as soon as it acquires.

Paul

Magnets

I removed the magnets by making a custom tip for a soldering iron that looked like a cookie cutter. It had an ID just larger than the magnet's OD and was an 1/8" deep. It melted a groove around the magnet that made it easy to pry the magnet out. This left 4 holes in the bottom, so I made a .020 round plate with a hole in the middle for the screw and bonded it to the bottom of the GPS with a small amount of JB weld. I'll post some pictures tonight.

-Chris

we're also using a garmin gps-18 (that we got through advanced flight systems) but splitting its output to other systems in nmea format as well.

just to be aware, there are several (sub)versions of the gps18.
ours had a d-sub connector attached, but turns out that this is only for garmin testing and the pinout unusable for regular operation or even reprogramming.
so we had to cut that off first.

then hooked up gnd and pwr pins to a switchable power supply set for the required 5v. in the airplane, these 5v are supplied through a connector from the advanced flight systems efis.
there are also versions for 12v etc... so make sure you have the right specs.

then default 3 pin serial hookup to a temporary d-sub (rx, tx, gnd) and sucessfully reprogrammed using the garmin software on my laptop. the heads-up with the mouse-driver turns out to be very valid, be ready to unplug the gps18 before the fake mouse inputs do any harm. then disable the mouse in the windows device manager all per the manual (if you want to use the nmea gps any further with the pc). otherwise everything is now set (in solid state memory) and from now on, the gps provides nmea standard 9600baud data to any device requiring it.

another one of the many many sub-projects. ;-)

don't know wheter this is required if the gps18 is only used for the advanced efis. either it uses binary data as configured per default or then does the reconfiguration by itself. since we feed other units with the data as well, had to do it manually.

rgds,
bernie

5vdc

I used the following inexpensive ($1.59) little regulator for supplying 5vdc to an iPaq PDA when using AnywhereMap:

http://www.radioshack.com/product/index.jsp?productId=2062599



Since it is good for one amp surely it would power a GPS18 if another source of 5vdc isn't available. I mounted the regulator to one of the sub-panel ribs so it would have a heat sink.

Removing Magnets

Here are a couple pictures of the tool I made to remove the magnets. The dimensions of the tool are: OD .420, ID .375 and depth .125. It has a shank to fit a cheep soldering iron.

The magnets are 5/16 diameter and .12 tall. You can easily see them under the overmolding.

I just let the tool get hot, roughly centered it over a magnet and pressed it in. Don't go any deeper than 1/8". After you remove the tool you can easily get the magnet out. Unfortunately, I didn't take any pictures of this step. After the magnets were out, I just glued a thin sheet onto the bottom to cover the holes.







-Chris