Really technical NMEA question

[cnh]

I am fitting a handheld chartplotter, and want to have a 6 way Buccaneer plug/socket (same as on autohelms) on the bulkhead. This is mainly to charge it, but also to leave open the option of interfacing it at some later date.

Unfortunately the cable has 7 wires: 0V, 12V, MNEA OUT +, MNEA OUT -, MNEA IN +, MNEA IN -, and a screen.

I need then to drop one of these. Will I need the screen in the future?

 

[Tradewinds]

Not really answering your question but suggesting a different waterproof plug might be a solution.

Index do a 7 pin - see here.

Dri-Plug do an 4-8 pin - here.

 

[rogerdog]

Simple answer is don't see Tradewinds post above - there is a quick and dirty method of loosing one of the wires - (use screen as neg etc or just remove) but you are potentially asking for problems.

Yes may work fine ... but not the right way to ensure maximum integrity

 

[maxi77]

You used to be able to buy the inserts for Buccaneer fittings, the shell is always the same.

 

[RestlessL]

As a general rule, the screen should be connected to gnd (0V) at one end of the cable only. If you can measure the resitance between the 0v wire and the screen (not connected to the unit), you should be able to determine if the screen is already conected to 0v. If it is not, then connect both screen and the 0v wire at the 6 pin plug.

John

 

[alan]

Typically on RS232 installations (same as NMEA) you only connect the screen at one end (usually the sender), so I don't see any problemw ith dropping it.
The reason for only connecting the screen at one end is to prevent "ground loops" betwee two different pieces of equipment.
Alan.

 

[rogerthebodger]

[ QUOTE ]
Typically on RS232 installations (same as NMEA)

[/ QUOTE ]

NMEA is not strictly RS232 it is RS422 using twisted pair cable not connected to logic ground. In most cases it will work when the NMEA- is connected to ground and NMEA+ connected to RS232 input.

 

[cnh]

[ QUOTE ]
In most cases it will work whrn the NMEA- is connected to ground and connected to RS232 input.

[/ QUOTE ]

I take it you mean NMEA + to RS232 input ... that's certainly what happens with my DSC GPS connection - there is no separate NMEA -.

I could, of course, leave them all disconnected except for the 0V and 12V. I'm trying to 'futureproof' the connection - but then, I can always take the plug apart at some later date.

 

[rogerthebodger]

Yes typing fingers too slow

 

[Refueler]

even with full bi-directional NMEA - you rarely need all connected.

Check manual for what is really needed.