EverFocus EDR-1610A - Manual (Page 14)

EDR910_1610_ma_en_rev1 00 - 14 -
2.3 RS-485 keyboard installation
All EDR910/1610 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.
2.3.1 General RS-485 bus installation
EKB-500 uses an RS-485 simplex wiring; the signal is transferred via a single twisted
pair line. CAT5 network cable is recommended, UPT version (unshielded) is sufficient for
normal application. A shielded cable should be used if the installed cables are expected to
be highly susceptible to interferences.
The number of devices installed in one bus is limited to 32 (expandable through signal
distributors).
Basically, the bus should be created by serial wiring, star wiring is only permitted using
signal distributors.
Maximum RS-485 bus cable length is 1200 m. Both the first and the last device are
normally 120 Ohm terminated in order to minimize line reflexions.
Cable length from box to device („Stubs“) has to be limited to 2m using connector boxes.
A direct RS-485 bus star wiring is not supported; star wiring requires the use of signal
distributors.
RS-485 bus serial wiring
RS-485 bus serial wiring with connector boxes and connection cable
Improper RS-485 bus star wiring