Grounding And Shielding; Figure A-5. Preferred Multipoint Wiring Using Shielded Twisted-Pair Cable With A Separate Signal Ground Wire; Figure A-6. Alternate Multipoint Wiring Using Shielded Twisted-Pair Cable Without A Separate Signal Ground Wire - Woodward 723PLUS Technical Manual

Manual 26482
The RS-422 specifications state that a ground wire is needed if there is no other
ground path between units. The preferred method to do this is to include a
separate wire in the cable that connects the circuit grounds together. Connect the
shield to earth ground at one point only. The alternate way is to connect all circuit
grounds to the shield, and then connect the shield to earth ground at one point
only. If the latter method is used, and there are non-isolated nodes on the party
line, connect the shield to ground at a non-isolated node, not an isolated node.
Figures A-5 and A-6 illustrate these cabling approaches.
Figure A-5. Preferred Multipoint Wiring Using Shielded Twisted-pair Cable with a
Figure A-6. Alternate Multipoint Wiring Using Shielded Twisted-pair Cable without
Woodward

Grounding and Shielding

Non-isolated nodes may not have a signal ground available. If signal
ground is not available, use the alternate wiring scheme in Figure A-5
with the signal ground connection removed on those nodes only.
Separate Signal Ground Wire
The SG (signal ground) connection is not required if signal ground is
unavailable.
a Separate Signal Ground Wire
723PLUS Digital Marine Control
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