Installing Garmin Radar with RADAR 5 plugin without adapter

[EXP]

I have a Garmin GMR 18 HD+ Radar which I want to use with open CPN on a RaspberryPi.

I know that to get it to work you need to make pin 5 switchable, and that an Amphenol MRJ*5780*01 adapter is recommended to make accessing the pins easier.

However, to route the radar ethernet cable I had to cut it and I did so near the end of Side A. I think it will work if I solder each wire back together but join extension wires to the blue and white wire (pin 5) & the drain wire (bare wire with no jacket) and then connect those to a switch.

I can then directly connect with the Radar cable without the need for the Amphenol MRJ*5780*01 adapter or another ethernet cable.

Can anyone confirm if this will work?

Below is a wiring diagram showing what I intend to do (obviously all cables will be properly soldered & heat-shrinked)

[AnsleyS]

I do not understand why you want to ground pin 5 by way of the switch. Would it not be better to put the switch on the power line, the red wire, and just turn off the power.

[EXP]

In the installation instructions for Garmin in the radar 5 plugin documentation:

https://opencpn-manuals.github.io/ma...-(Garmin).html

It states:

'When there is no Garmin chartplotter involved, you can make a direct connection between the computer and the scanner, but in this case it is imperative that you make pin 5 switchable to power up the scanner. An example configuration could look like this:'



I think I could achieve the same as this but without the Amphenol MRJ-5780-01 adapter with my proposed wiring diagram.

[Hakan]

EXP..
It would be pin 5 on the cable to the radar scanner that shall be connected to ground.

Not (only) the cable to switch/PC as in this case without the "Garmin Ethernet switch".
As I parse you picture it seems you have done it the other way?
Pin 5 is normally not used for data traffic. Only for e.g. POI.

[EXP]

Hakan..

Thanks for the reply.

The ethernet cable that I would switch pin 5 with ground would be the one connected to the scanner, it would be the original Garmin ethernet cable.
I would just be doing it where I cut the cable rather than using the Amphenol MRJ-5780-01 adapter.

I should then be able to connect the rejoined Garmin ethernet plug end directly to the switch or Raspberry Pi as pin 5 and ground would have a switch where I cut the cable.

I hope this makes sense.

[Bellinghamster]

I recommend using RJ-45 terminations to re-make the connection rather than soldering. Crimp a shielded RJ-45 plug on the radar cable and a shielded keystone jack on the end of the cable to the ethernet switch (https://www.truecable.com/products/c...d#&gid=1&pid=1 or similar), pulling out the wire for pin5, through your radar-enable switch and back to shield. Terminate the other wires normally. Of course needs to live in a dry location...

If you solder, make sure you maintain the twist of the pairs through the splice. and remember to slide the heatshrink on pair wires AND cable jacket before soldering!

[EXP]

There maybe something I’m not getting as I’ve never had much technical experience with wiring ethernet cables, but I don't understand why I can't pull out the pin 5 wire and the drain wire where the cable is currently cut and then connect them to a switch. I would then either rejoin the cable to the existing Garmin plug or terminate the rest of the wires with a new RJ45 plug.

Then I could connect the Garmin ethernet cable directly to RaspberryPi. Why is there a need for another ethernet cable when pin 5 to ground switch has been made at the cut of the original Garmin Ethernet cable.

[wholybee]

Originally Posted by EXP

There maybe something I’m not getting as I’ve never had much technical experience with wiring ethernet cables, but I don't understand why I can't pull out the pin 5 wire and the drain wire where the cable is currently cut and then connect them to a switch. I would then either rejoin the cable to the existing Garmin plug or terminate the rest of the wires with a new RJ45 plug.

Then I could connect the Garmin ethernet cable directly to RaspberryPi. Why is there a need for another ethernet cable when pin 5 to ground switch has been made at the cut of the original Garmin Ethernet cable.

Somehow my previous reply got lost. You can basically do what you suggest. But, pin 5 needs to be connected through, in addition to the switch to ground. And the wire on pin 5 must remain exactly the same length as the wire it is twisted with. And soldering is a bad idea. It can lead to errors and/or reduced speeds. So to maintain best reliability it is easier to use a cat5 union or joiner, and solder unto the circuit board instead of the wires themselves.