nmea 0183 connections 295 to lowrance hds10



Hi Snips
Not sure if you have answered this one elsewhere, if you have please point me there. If not, can you please help
I assume
Furuno TD-A to Lowrance RX1 (Orange)
Furuno RD-A to Lowrance TX1 (Yellow)
Furuno Shield on Pin 7 to Lowrance shield
I am guessing that as I am only connecting one device, I only need to connect TD-A and RD-A and RX1 and TX1
I am also assuming that this is single ended and not differential ?
Your help will be greatly appreciated
Eric Leigh
You would normally make a two wire (or four wire) connection between devices BUT NOT you stated.
First off, you will not normally connect the Shield. The shield of the cable is designed to short EMI noise. It is internally grounded in the unit so if you were to connect the two shields, it would create a path of electrical flow. This could cause grounding loops or power differential issues. There are of course exceptions; depending and the equipment.

It appears that you are attempting to connect a RS422 Current loop NMEA 0183 Furuno connection to a RS232 NMEA 0183 Lowrance. This normally is done with a proper level converter (RS422 to RS232). Does the Lowrance not have a NMEA input negitive or a NMEA output negitive? If it only has a RX1+/TX1+ then they are most likely using a single grounding system. (Like RS232) If you make the connection, only ONE listener (this Lowrance) can be connected to the FCV295. If you want more, you will need to purchase a NMEA expander/level converter like the Noland Engineering XP15.

Here are some examples of discussions here on the Forum that you might find helpful.

Assuming there are no NMEA negatives’ on the Lowrance; If you only wish to connect the Lowrance and nothing else, you can wire it like you said (except for the shield) and then take the Furuno RD- and TD- to the ground of the Lowrance.
Hi Johny
All working now. I had to connect all 4 wires from the Lowrance. Wouldn't work with just 2 connected