Honeywell Galaxy Dimension Series Installer Manual page 22

RS485 Recommendations
4. Shielded twisted pair cable, where used, is connected to the earthing pillar on the Galaxy control
panel using the P-clip and nut supplied (refer to Figure 2-8).
The RS485 (AB) line must have a 680 Ω resistor fitted across the A and B terminals of the last
5.
module on the line. If twin lines are connected, both ends must be terminated with 680 Ω resistors and
the appropriate link on the control panel PCB must be removed (refer to figure 2-7).
6. There must only be a single AB pair of wires in each of the cables.
7. The minimum supply voltage level is 10.5 Vd.c. with 12.5 Vd.c. being the recommended working
minimum.
8. The power supply in the Galaxy control panel and remote power supplies must not be connected
in parallel.
9. The 0 V of all remote power supplies should be connected in common to the 0 V of the Galaxy
control panel.
10. Ensure that any extension loudspeakers are not wired in the same cable as an AB pair of wires.
11. Where possible, ensure that the AB cable is at least 30 centimetres away from any other cables.
12. Where possible, ensure that the AB cable does not run parallel to other cables for extended
distances (maximum 5 metres).
P-clip
AB connectors
A
data line
RS 485 cable
Figure 2-8. Connection of cable screen using P-Clip
Galaxy Dimension Installer Manual
B
data line
Cable screen
Nut
P-clip
Earthing pillar
(threaded)
2-10