Silva NX2, Service Manual

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60ServerNX2.doc Page 1 Latest update: 13 Jan -03
6.0 NX2 SERVER
The Server is the ”heart” of the NEXUS Navigation Network to which transducers
for speed, depth, compass, wind and navigation are connected.
From the Server the single NEXUS cable transmits power and data to the
instruments, which repeats the information sent from the Server or other NX2
transducers.
The NX2 Server also have communication possibility to other equipment via
NMEA signal protocol.
The Nexus Network is designed with the industry standard RS 485 data bus,
which allows you to connect up to 32 NX2 instrument units on the single Nexus
Network cable, thereby allowing you the flexibility to easily develop your system.
The Nexus Network is capable of carrying data 10 times faster than NMEA 0183.
Network Manager - Principal of operation
Every NX2 Navigation Network need to have a Network Manager. A very typical
Network Manager or ”bus-master” is the Server, but even the Autopilot Servo,
Wind Data / Compass Data instruments and GPS Navigator instrument can be a
”bus-master”.
A ”bus-master” is responsible for initialisation of the network at start, e.g. call for
known units and give them so called ”next-sender” address. This is the identity
(ID) for this instrument which (when receiving data) is given right to ”talk” on the
network. The instrument then can talk, or direct give away the right to talk by a
new ”next-sender” ID etc. The Network Manager also:
•
Superintend the Network so if some unit disappears (gone out of order or is
taken away) then the Network shall be re-initialised.