Analog Transducer to NMEA wiring question

[Mr Googler]

I have bought the garmin analog to nmea 2000 converter.

The garmin install manual as below states to connect the bare (shield) wire to the green wire.



However.....having chopped the wire of the existing transducer....there are 2 bare shield wires. The transducer wiring diagram is below.



Do I have to figure out which shield wire is for the depth function or can I connect both bare shield wires together. Only the depth function will be used. I’m a bit lost with what shield wires do to be honest.

 

[vas]

for sure nothing's going to explode if you connect both bare shield wires together and actually if you aren't connecting anything else bar the depth on pin1 and all shields on pin6 it will work.

Now, I'd try the one, see if I do get depth, fine your chances are really 50-50, if not swap over.

Mind, having spent all that money to get the converter, why not get the speed and temp working as well?
Good practice to cut power to the system while doing any connections and thus resetting the NMEA2000 bus to start afresh with whatever you've done.

where are data going to be presented?

cheers

V.

 

[Mr Googler]

Thanks Vas. Was hoping you’d be along

It’s a skim transducer mounted inside the hull as a shoot through so temp and speed won’t work anyway.

Depth will be displayed on the Garmin plotter (4008)

I’ll connect the bare wires one at a time and see what happens and will power off in between times.

As a learning point, what are shield wires for?

Thanks very much

 

[vas]

following para in red is all wrong check two posts below!
basically the "return" path for the whatever current goes through.
I mean you really need TWO wires to get a signal across, so let's say that pin1 is the + and this shield is the negative... hence no problem if you get them both together as long as you don't connect the other pins. It wouldn't go bang even if you did, just you could possibly get offset values.

OK, so do temp as well, it WILL show up something reasonable and then you can offset the value on the 4008 by as many degrees as you wish.
I'm assuming a solid GRP where you have the sensor fitted and NOT a cored one.

cheers

V

 

[Mr Googler]

Yes, solid core....1992 Sunseeker......the good old days of hull layup

Thanks for the explanation. I got confused as there is a + and - wire and the shield.

 

[vas]

Yes, solid core....1992 Sunseeker......the good old days of hull layup

Thanks for the explanation. I got confused as there is a + and - wire and the shield.

Opps! doc I've been talking balls!

just checked the drawing again. Discard my previous reply:

you NEED DEPTH + on pin1
you NEED DEPTH - on pin5

you rather fit shield on pin6, but pretty sure it will work without it as well.
So shield is a what the word says, a protector to the signals conveyed by + and - so that other el. signals floating around are NOT affecting them and shifting them about.

sorry, missed pin5 before

cheers

V.

 

[Mr Googler]

Brilliant....thanks vas. I wasn’t sure if using the wrong shield would mess things up but as the other wires will not be connected, hopefully it won’t matter