Wiring the X-BUS interface

The X-BUS interface provides for the connection of expanders to the controller. The X-BUS can be wired in a number of different configurations depending on the installation requirements. The X-BUS interface baud rate is 307kb.

NOTICE: The X-BUS is an RS-485 bus with a baud rate of 307kb. The full performance is only supported in loop (see Loop configuration) and spur (see Spur configuration) wiring configuration (best signal quality due to daisy chain of isolated sections with 1 transmitter/1 receiver and balanced terminating resistors on each end). The performance in star or multi-drop configuration wiring (see Star and multi-drop configuration) is limited due to non-optimal conditions of the RS-485 bus specification (reduced signal quality due to multiple receivers/transmitters in parallel with unbalanced terminating resistors).

 

NOTICE: It is strongly recommended to use loop (see Loop configuration) or spur (see Spur configuration) configuration.

The table below shows the maximum distances between controller/expander or expander/expander for all cable types in loop and spur configuration.

Cable Type	Distance
CQR standard alarm cable	200 m
UTP Category: 5 (solid core)	400 m
Belden 9829	400 m
IYSTY 2 x 2 x 0.6 (min)	400 m

Each device has 4 terminals (1A, 1B, 2A, 2B) for connection to expanders via the X-BUS cable. The controller initiates a detection procedure on power up to determine the number of expanders connected on the system and the topology in which they are connected.

Wiring expander

Number	Description
1	Previous expander
2	Next expander
3	SPC controller

Most expanders are equipped with additional terminals 3A/3B and 4A/4B for branch expander wiring. See Wiring of branch expander for instructions on branch expander wiring.