EverFocus HD-CCTV EPHD08 - Manual (Page 22)

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Output relay in idle state
2.4 RS-485 keyboard / PTZ Installation
All functions can be remote-controlled by the EKB-500 universal keyboard. Using the EEPbus protocol,
digital video recorders, keyboards and speed domes can be installed on one single RS-485 bus. One
system can comprise up to 8 keyboards.
2.4.1 General RS-485 bus installation
The EKB-500 keyboard uses a RS-485 simplex wiring; the signal is transferred via a single twisted pair line.
CAT5 network cable is recommended, UTP version (unshielded) is sufficient for normal applications. A
shielded cable should be used if the installed cables are expected to be highly susceptible to interference.
The number of devices installed in one bus is limited to 32, and the maximum cable length is 3,900 feet.
Both of these can be expanded using a signal distributor EverFocus Model EDA997A (see below).
Both the first and the last device in series should be terminated with 120 Ohm resistance in order to
minimize line reflections.
RS-485 bus serial wiring
Cable length from box to device („Stubs“) has to be limited to 2m using connector boxes.
RS-485 bus serial wiring with connector boxes and connection cable
Direct RS-485 bus star wiring is not supported unless using an EverFocus Model EDA997A (see below).
Improper RS-485 bus star wiring