| NOTICE: See Examples of correct wiring, Examples of incorrect wiring and Shielding before starting the installation. |
The star and multi-drop cabling methods enables takeover of existing wirings with four-core cables in small buildings (typically homes) with low electrical noise environment. These wiring methods are limited to the specifications below:
| SPC42xx/SPC43xx | SPC52xx/SPC53xx/SPC63xx | |
|---|---|---|
|
Max. expanders/keypads |
8 |
16 (8 per X-BUS port) |
|
Total cable length |
200 m |
200 m |
| NOTICE: The performance in star or multi-drop configuration wiring 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). |
Star configuration
| NOTICE: All expanders/keypads are fitted with a termination jumper by default. In star configuration it’s imperative to remove these jumpers. |
A star configuration is established when multiple expanders are wired back to the same X-BUS port on the SPC controller. Depending on controller type 2 ports may exist (1A/1B, 2A/2B), however only one port (1A/1B) is to be used on each keypad or expander.
In the case of a X-BUS break the single will be disconnected, all other expanders and detectors continue to be supervised. A short in the cable renders all expanders disabled.
Star configuration
Star configuration 2
| Number | Description |
|---|---|
|
1 |
SPC Controller |
|
2-4 |
Expanders |
Multi-drop configuration
| NOTICE: All expanders/keypads are fitted with a termination jumper by default. In multi-drop configuration it’s imperative to remove these jumpers with exception of last keypad or expander. |
The multi-drop configuration varies in that each expander uses the same communication channel as it wires onto the next expander, with all expanders using the same input channel. See multi-drop configuration in the second figure.
In the case of a X-BUS break, all expanders and detectors up to the fault continues to be supervised. A short in the cable renders all expanders disabled.
Multi-drop configuration
Multi-drop configuration 2
| Number | Description |
|---|---|
|
1 |
SPC controller |
|
2-4 |
Expanders |