NDP-JTH
NEXSYS HUB
Features
• Extends NexSys control to up to 1024 devices
• Two electrically-isolated, balanced NexSys busses
• NexSys busses and 8 user-programmable control I/O ports use
Phoenix COMBICON
®
connections; TTL and relay-driving outputs
available
• Front panel status indication and power switch
• Rear panel data present indicators
• IEC power receptacle
• 1 rack unit high; width & depth same as Crest Audio’s CK family
of Power Processing amplifiers
• Five year warranty
Product Information
Crest Audio's NexSys Hub in an integral part of any
NexSys computer-controlled network that needs to sup-
port more than 32 amplifiers or nodes.
The maximum number of amplifiers connected to one
NexSys bus is limited by the NexSys Network's adher-
ence to the “ANSI TIA/EIA-485” recommended standard
(or “RS-485”). A NexSys bus, which consists of multiple
amps connected by a length of twisted-pair cable with
two termination-resistors, is limited by RS485 to a maxi-
mum of 32 amplifiers. The NexSys Hub, acting as a
repeater, allows for the connection of multiple NexSys
buses.
Thus, the Hub extends NexSys computer control beyond
the RS-485 node limitation to a maximum of 1024 ampli-
fiers.
The figure below shows a typical NexSys Network that is
designed to control more than 32 amps. Each Hub resides
on the bus that is connected to the NexSys BusServer
card. This bus is defined as the “primary bus”. Each Hub
is responsible for passing network data from the primary
bus to all amplifiers residing on its 'secondary bus”.
Thus, in effect, every amplifier in the NexSys network is
“connected” to the BusServer card. (Note that a Hub can-
not be connected to the secondary bus of another Hub on
the network.)
Programmable Control I/O
Eight programmable control ports are available on the
Hub. They can serve as either inputs or outputs. When
configured as an input, the Hub can sense a switch clo-
sure, a variable DC voltage, or a 3-contact potentiometer.
Inputs may then be interfaced to NexSys and/or the Event
Scheduler in order to automate NexSys functions from
external controls. When configured as an output, the Hub
can drive a TTL signal. NexSys and/or the Event
Scheduler may then be interfaced to external devices or
indicators.
Crest Audio NexSys Hubs are manufactured exclusively
in our USA facility, using only the highest quality select-
ed internal components.
BUS
SERVER
NDP-JTH
HUB
NDP-JTH
HUB
AMPLIFIER
AMPLIFIER
AMPLIFIER
AMPLIFIER
AMPLIFIER
AMPLIFIER
AMPLIFIER
AMPLIFIER
AMPLIFIER
Primary
Network
(RS-485)
Secondary
Network 1
(RS-485)
Secondary
Network 2
(RS-485)
Network
may contain up
to a total of 32
devices
Network
may contain up
to a total of 32
devices
Network
may contain up
to a total of 32
devices
