Soon be installing
AIS and a multiplexor, connecting to a
chartplotter.
Have a few questions regarding the shield wire on the
NMEA cables.
1) From various bits of
research, the shield wire should only be grounded at the talker end of the circuit, this is to avoid ground loops (there will be a question on ground loops later)
2) Will it be OK to connect all the shield wires to a common connection point, say a bus bar, or a copper strip?
3) If item (2) is OK, where do I connect the common ground point to. Is it OK to ground to the
engine block, or can it be connected to the
battery return cable at the switch panel
4) The multiplexor, this will be a listener and a talker. The
NMEA plug on the chart plotter contains both input and output NMEA pairs, plus a shield wire. I assume that the shield wire in the
plug somehow is grounded through the plotter. The multiplexor will receive NMEA from the
chartplotter at a baud rate of 38,400, then converts that to 4800 baud rate so I can get NMEA data to
DSC and
radar. Should I ground the shield wire of the cable from the multiplexors 4800 output port?
5) What problems do ground loops cause, I don’t want to make a ground loop, just interested in what havoc it can cause.
I want to keep the present system for the time being, so please, no suggestions to bin it, or sell it, and fit a N2K system or similar, thanks