American Dynamics MegaPower 48 Plus, Installation Manual

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16
MegaPower TM 48+
Cable Networks
Cable networks provide the means through which the MegaPower 48+ Main Electronics Unit communicates with receiver/
driver units and domes. Three types of networks can be used with the Manchester, SensorNet, or SEC-RS422 protocols.
• Daisy Chain – in a daisy chain configuration, a separate cable connects each device to the next device in the chain
(Fig. A).
• Backbone – in a backbone configuration, a single, continuous cable connects all domes in the network link (Fig. B).
• Star – in a star configuration, up to four branches connect to a central hub location (typically a J-Box or other data
distribution unit). Domes can attach with separate cables (daisy chain style) as shown in Fig.C, or, with a single
continuous cable (backbone style) as shown in Fig. D.
Note : both ends of a cable run must be terminated. Black device blocks illustrated above indicate terminated devices.
System Communications
The MegaPower 48+ CPU communicates with system devices through four communications protocols:
• RS232 (PC icon)
• SEC-RS422 (dome icon)
• SensorNet (dome icon)
• Manchester (dome icon)
RS422, SensorNet and Manchester protocols are used in the control of domes and pan/tilt cameras.
RS232 enables communications with system keyboards, PCs, auxiliaries, alarm interface units, external modems, port
expanders, and video recorder interface units.
Manchester Communications
There is a single Manchester connector on the MegaPower 48+ patch panel. The connector consists of three terminals
labeled
Black (B), White (W), and Shield (S). Manchester is a one-way communications protocol.
• Cable required: 18 AWG, 2-wire, shielded twisted pair. polarized, Belden 8760 or equivalent
For Plenum applications, Belden 88760 or equivalent
• Maximum distance: 5000 feet (1.5km)
• Data rate: 31 kb/sec
Daisy Chain Connections
When wired directly from the patch panel connector to a receiver/driver or integrated dome in a Manchester network, a
maximum of three video sources can be connected via a daisy chain connection
. The last unit in the daisy chain must
be terminated at 120 ohms. See Drawing 8, Page 17 for a typical direct connection to an AD1641 Receiver.
AD2083-02B Code Translator
The MegaPower 48+ CPU can output Manchester code to control domes utilizing the SEC-RS422 communications
protocol by using the AD2083-02B Code Translator as an interface between the patch panel and the domes.
A single AD2083-02B provides 16 terminals using the 4-wire RS422 protocol. DIP switches on the rear panel of the
AD2083-02B enable addressing for specific groups of cameras. All 48 video inputs for the MegaPower 48+ patch panel
can be connected through a single AD2083-02B by wiring each terminal to a three-dome daisy chain group.
See Drawing 9, Page 18 for a typical connection from the MegaPower 48+ Manchester terminals to an AD2083-02B to
an integrated dome.