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Discussion Starter · #1 · (Edited)
Hi everyone,

In the past couple of days I have been trying to install a simple NMEA 2K network consisting of a Garmin GMI 10 MFD, an Airmar 800DST Triducer, a Garmin GWS 10 Wind sensor and a Garmin GPS 19X HVS (NMEA0183 version). So far I have only dealt with the triducer, gps and the display, since weather has not allowed to install the wind sensor.

I have followed the installation instructions to a tee, but I have run into two problems that have me at my wits' end. The cabling is correct to my knowledge and a diagram of the installation is available in the location below but I cannot add the image to the post due to low post count.

h t t p://i.imgur.com/1Djt3On.png

Here are the problems:

1. No GPS data at all!! I have moved the antenna to a clear view of the sky but not even satellite view comes up on GMI10.
2. On a dry fit, all triducer data showed up correctly, but after installation of the triducer in the thru-hull and running the cable through the bilge, speed & temperature shows up from the triducer but depth shows up some times and sometimes it doesn't!!! Funny thing is that when depth showed up at some point it was only when the GPS19X was disconnected from GMI10, which does not make any sense, since they are not on the same data bus! (the gps is directly connected to GMI as a NMEA0183 device.

I tried different connections of the drop cables (power drop cable in the middle, left or right) to the backbone which consists only of 3 T-connectors, 3 drop cables, terminating resistors and no backbone cable.

The two things I haven't tried so far is to ground the power cable (the bare wire it contains was not shown to be needed to connect to the ship's ground in the instructions so I left it unconnected) and to use the limiting resistor for 1Hz operation of the GPS (instead of 10Hz, which I was under the impression that GMI10 supports)

If someone can help me sort out this mess, I would be grateful, since I spent an entire weekend passing cables through very tight spots only to have only half of the functionality...

Thank you in advance
 

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Discussion Starter · #3 · (Edited)
Thank you for the reply. I will ground the power cable and test again but I don't understand why it should cause an issue not grounding the power (and why it is not explicitly included in the installation instructions that the power drop cable must be grounded).

EDIT: in another document from Garmin I found online it clearly states that the power cable must be grounded (w w w.cnerd.com/interesting/boating/GPSMAP4008_NMEA2000NetworkFundamentals.pdf page 5). I wonder why this is not included in the GMI10 installation instructions!

As far as the GPS 19X goes, I checked the cable end connector that goes to the gps unit with a multimeter on the V+ an V- pins (2 & 3, if I recall correctly) and it registered a normal 12.70Volts without fluctuations.

For the triducer problem, since I don't have a NMEA2000-PC gateway, I cannot test the NMEA sentences sent throughout the network to analyse for potential errors but since some data is transmitted (temp, speed) I don't understand what would cause the erratic behavior of the depth data.
 

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Discussion Starter · #5 ·
Don't worry, I am not insulted. Although a computer programmer by trade, when it comes to NMEA network installations I am a neophyte :)

To answer your questions, yes, all connections are as in the diagram I included in the first post. In detail:

Backbone: female terminator - T -T - T - male terminator.
Drop cables: GMI 10 - Power - Triducer to each respective T middle connector

GPS 19X cable connected to the respective cable that ends at the Power/NMEA0183 connector at the back of GMI 10 and both GMI 10 and GPS 19X get power from direct wire connections to a switch on the 12V electrical panel and NOT from the NMEA2000 bus.

GMI 10 is a headless MFD, it just displays information from external sensors, it is not a chartplotter or GPS receiver itself.
 

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Discussion Starter · #15 ·
Hi everyone and thank you for your input.

Some info: The boat is on the hard and the depth sounder gave readings at some point when pointed either to the ground below or to thick GRP sections of the boat itself (incorrect depths to be exact - probably because it gets readings through the air and not water)

In the manual I used it says that GMI 10 DOES NOT get power through the NMEA2000 network. In fact, I tried both ways, and GMI 10 DID turn on when only powered by the NMEA2000 bus. In either case the results were the same.
I will give the common ground thing a go when I get back to the boat, since it seems the only thing that makes some sense to affect normal operation by cancelling noise on the data lines and the one thing I haven't tried.

Again, thank you all for chiming in. :)
 

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Discussion Starter · #21 · (Edited)
Hi everyone, just an update here to let you know the problem with the GPS not getting picked up by the MFD was fixed by grounding the NMEA2000 power drop cable. I also installed the resistor to the GPS TX that limits the refresh to 1Hz, just in case. Anyhow, if it works... don't fix it :)
Also, I installed the GWI10 Wind Sensor on the masthead and that works flawlessly. The depth transducer is still a bit erratic in behavior but I reserve final judgement until the boat is in the water.

Now, let's see if I can pinpoint why my nav lights and steaming light don't work after switching to LED bulbs (god, I hate electrical systems and climbing the mast just to check if current reaches the steaming light fixture) :)
 
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