v. 2.3 10/3/97
NDP-JTH NEXSYS HUB
SPECIFICATIONS
Architect’s & Engineer’s Specifications
The network Hub shall contain two electrically isolated Crest Audio NexSys busses.
One bus shall be dedicated to the primary network (which includes the network’s bus
server). The other bus shall be dedicated to the secondary network and provide access
to as many as 32 additional NexSys network nodes. Any node on the secondary net-
work shall be accessible to the bus server through the network hub. Each NexSys bus
shall conform with RS485 electrical serial protocol.
The network hub shall poll the status of each node on the secondary network indepen-
dently from the bus server. The hub shall also send commands to nodes on the sec-
ondary network as dictated by the bus server on the primary network.
The network hub shall contain eight programmable control ports to accommodate
external inputs to NexSys via switch closure, variable DC voltage, or 3-contact poten-
tiometers. The control ports shall also have TTL outputs and relay-driving outputs
available to control external devices from NexSys.
The front panel shall include an on/off power switch and an LED to indicate power
status. The rear panel shall be fitted with the two sets of dual rotary switches with the
purpose of assigning NexSys data bus addresses to the hub. It shall also be fitted with
data present indicators, and the following 5mm, 3-pin Phoenix COMBICON®connec-
tors: two for NexSys primary network access, two for NexSys secondary network
access, and eight for programmable I/O control ports.
An IEC AC mains socket shall be provided on the rear panel. 120V and 220V versions
shall be available. A single AC mains cord having an appropriate plug for the intend-
ed operating voltage shall be provided. Dimensions shall be 19" (483mm) wide, 1.75"
(44mm) high, and 17.13" (435mm) deep. The network hub shall be designated the
Crest Audio model NDP-JTH.
Control I/O
Address
Hi
Lo
0
8
1
9
2
A
3
B
4
C
5
D
6
E
7
F
0
8
1
9
2
A
3
B
4
C
5
D
6
E
7
F
Data
+–
+–
NexSys Network
Address
Hi
Lo
0
8
1
9
2
A
3
B
4
C
5
D
6
E
7
F
0
8
1
9
2
A
3
B
4
C
5
D
6
E
7
F
Data
+–
+–
1234
5678
Model NDP-JTH
NexSys
Secondary Network
Block
Diagrams
Crest Audio Inc.
100 Eisenhower Dr., Paramus NJ 07652 USA
TEL: 201.909.8700 FAX: 201.909.8744
http://www.crestaudio.com
NexSys is a registered trademark of Crest Audio Inc. Crest
Audio reserves the right to make improvements in manufac-
turing or design which may affect specification. Crest Audio
specification literature is available in downloadable PDF for-
mat; visit our website at: http://www.crestaudio.com.
©1997 Crest Audio Inc.
A3300039
Electrical Specifications
AC Line Current Maximum: 165 mA., @ 120V
Typical: 65 mA., @ 120V
NexSys Interface One pair primary NexSys bus
connections, one pair secondary
NexSys bus connections; both
electrically isolated, on standard
two wire RS-485, single unshield-
ed twisted pair
I/O Connector Function pin 1: 470Ωpullup to +5V
pin 2: I/O
pin 3: selectable reference -
circuit ground (factory);
or user reference
(pin 3 selection globally configures all 8 control I/O ports)
I/O Input Voltage Range 0 to 8V
I/O Max Sink Current 80mA per output,
500mA total
I/O Breakdown Voltage 40V
No internal clamp diodes provided on I/O
MICRO
COMPUTER DUAL
PORT
MICRO
COMPUTER
BUS
CONN.
BUS
ADDRESS
SWITCH*
DATA PRESENT
INDICATOR
SECONDARY BUS
PRIMARY BUS
BUS
CONN.
BUS
ADDRESS
SWITCH
DATA
PRESENT
INDICATOR
I/O
(1 OF 8)
470
+5 A/D
JTH GND
*This Bus Address Switch is reserved for future expansion
V
0 TO 8V CLOSURE POT OPTO
OPTO LED TTL RELAY
+V
INPUTS
OUTPUTS
Pin 1
Pin 2
Pin 3
Pin 1
Pin 2
Pin 3
I/O
CONTROL
