NORTHROP GRUMMAN naviguide 4000, Руководство пользователя, по установке и обслуживанию

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NAVIGUIDE 4000 056336 Rev. AA
4.2: Electrical Installation Page 4–3
4.2.2.2 Bus Termination
The NAVINET 4000 bus must be terminated at both ends with a 120
Ω
resistor.
Fig. 4–1:
NAVINET 4000
bus termina-
tion
The SCU and the NAVINET 4000 connection boards contain on-board termination
resistors. These must be removed from the bus except for the two resistors lo-
cated at the physical ends of the bus backbone.
On NAVINET 4000 connection boards, one of the two on-board resistors must be
removed if the respective board is located at the physical end of the backbone. If
the board is spliced into the bus, both resistors must be removed.
On the SCU PCB, the termination resistor is connected to the bus when the
jumper connection E23-E24 is closed (see Fig.4–4). Only in an SCU located at the
physical end of the backbone , the jumper connection may be closed.
Fig. 4–2:
Termination
with an SCU at
the physical
end of the bus
If the termination resistor on the SCU PCB is not to be used, verify that the jumper
connection E23-E24 is open.
Fig. 4–3:
Termination
with an SCU
spliced into the
bus
4.2.2.3 Bus Shielding/Grounding
The NAVINET 4000 shield must be grounded at only one point on the bus. All
other taps or splices must pass the shield through to the connection at the destina-
tion device. Equipment ground and other cable shield grounds must be kept sep-
arate.
In all cases, use proper shield grounding techniques, usually connecting the shield
to the vessel hull ground at only one point.
NAVINET 4000 Bus Backbone
120
Ω
120
Ω
stubs
nodes
stubs
nodes
stubs
nodes
120
Ω
120
Ω
120
Ω
120
Ω
120
Ω
120
Ω
120
Ω
120
Ω
120
Ω
120
Ω
120
Ω
120
Ω