User's Manual

Page 5
3E3140 Gallagher T20 Terminal Installaon Note | Edion 16 | March 2016
Copyright © Gallagher Group Limited
2.3 Cabling
The Gallagher T20 Terminal requires a minimum cable size of 4 core 24 AWG (0.2 mm
2
) stranded
security cable. This cable allows the transmission of data (2 wires) and power (2 wires). When
using a single cable to carry both power supply and data, both the power supply voltage drop
and data requirements must be considered. Although the terminal is specied to operate at 9
Vdc, for good engineering design it is recommended that the voltage at the terminal should be
approximately 12 Vdc.
HBUS cabling topology
The HBUS communicaons protocol is based on the RS485 standard and allows the terminal to
communicate over a distance of up to 500 m (1640 ).
The cabling between HBUS devices should be done in a "daisy chain" topology,
(i.e. A "T" or "Star" topology should not be used between devices). Should "Star" or "Home-Run"
wiring be required, the HBUS 4H/8H Modules and the HBUS Door Module allow mulple HBUS
devices to be individually wired to the one physical locaon.
The end devices on the HBUS cable should be terminated using 120 ohms resistance. To
terminate the Gallagher Controller 6000, connect the supplied on-board terminaon jumpers to
the Controller. To terminate the Gallagher T20 Terminal, connect the orange (terminaon) wire
to the green (HBUS A) wire. Terminaon is already included at the HBUS Module, (i.e. each HBUS
port is permanently terminated at the module).
Connect the on-board
terminaon jumper
Controller 6000
RS485 1
HBUS
Device
"T" or "Star" circuits are
not permied between
HBUS devices
HBUS
Device
Terminate
HBUS
Device
HBUS
Device
HBUS
Device
HBUS
Device
HBUS
Device
HBUS
Device
Terminate
Remove the on-board
terminaon jumper
RS485 1
"T" or "Star" circuits are
not permied between
HBUS devices
HBUS
Device
Terminate
HBUS
Device
Controller 6000