Crest audio NDP-JTH SPECIFICATIONS

NDP-JTH

NEXSYS HUB

Product Information

Crest Audio's NexSys Hub in an integral part of any NexSys computer-controlled network that needs to support more than 32 amplifiers or nodes.

The maximum number of amplifiers connected to one NexSys bus is limited by the NexSys Network's adherence 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 maximum 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 amplifiers.

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 cannot be connected to the secondary bus of another Hub on the network.)

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

BUS

SERVER

AMPLIFIER

NDP-JTH

HUB

Secondary

Network 1

(RS-485)

AMPLIFIER

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 closure, 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 selected internal components.

Primary Network

(RS-485)

Network may contain up to a total of 32

devices

NDP-JTH

HUB

Network may contain up to a total of 32

devices

Secondary

Network 2

(RS-485)

Network may contain up to a total of 32

devices

AMPLIFIER

NDP-JTH NEXSYS HUB

SPECIFICATIONS

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 unshielded 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

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 network 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 independently from the bus server. The hub shall also send commands to nodes on the secondary 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 potentiometers. 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 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 intended 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.

connec-

Block Diagrams

Model NDP-JTH

PRIMARY BUS

BUS

CONN.

BUS

ADDRESS

SWITCH

DATA

PRESENT

INDICATOR

I/O

(1 OF 8)

Address

NexSys Network

–

SECONDARY BUS

BUS

MICRO

COMPUTER

DUAL

PORT

MICRO

COMPUTER

CONN.

BUS

ADDRESS

SWITCH*

DATA PRESENT

INDICATOR

*This Bus Address Switch is reserved for future expansion

470

JTH GND

A/D

INPUTS

OUTPUTS

0 TO 8V

CLOSURE POT OPTO

Pin 1

Pin 2

Pin 3

Pin 1

Pin 2

Pin 3

CONTROL

I/O

Address

NexSys

Secondary Network

Data

–

Data

–

Control I/O

OPTO

LED

TTL RELAY

v. 2.3 10/3/97

A3300039

NexSys is a registered trademark of Crest Audio Inc. Crest Audio reserves the right to make improvements in manufacturing or design which may affect specification. Crest Audio specification literature is available in downloadable PDF format; visit our website at: http://www.crestaudio.com.

100 Eisenhower Dr., Paramus NJ 07652 USA

Crest Audio Inc.

TEL: 201.909.8700 FAX: 201.909.8744

http://www.crestaudio.com