Lenel OnGuard Hardware Installation Manual page 83

14.1.3 Downstream Device Communication
The ISC can be configured to communicate downstream with up to 16 input/output devices, using Port 2,
Port 3, Port 4, and Port 5. Each of these ports can be wired only as an RS-485 interface, for multi-drop
communication on a single bus of up to 4000 feet.
For Ports 2-5, the following type of RS-485 cable is required: 24 AWG (minimum) twisted pair (with
shields.) Either 2-wire or 4-wire RS-485 cable configuration can be used. The main run RS-485 cable should
be no longer than 4000 feet (1219 m), 100 ohms maximum (Belden 9842 4-wire or 9841 2-wire, plenum
cabling Belden 88102 or equivalent). The drop cables (to readers and other devices) should be kept as short
as possible, no longer than 10 feet.
Each RS-485 line should contain only 2 terminators, one at each end.
2-WIRE
Downstream Device Communication Wiring (Ports 2-5)
Ports 2 - 5
RS-485
TR2 +
TR2 -
GND
TR3 +
TR3 -
GND
GND T- T+
Hardware Installation Guide
TR2 +
TR2 -
GND
TR3 +
TR3 -
GND
TR4 +
TR4 -
GND
TR5 +
TR5 -
GND
TR- TR+ R- R+ SG
Downstream Device
4-WIRE
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