Memory; Rs485 Data Communication Bus (Ab Lines); Rs485 Wiring Configurations - Honeywell Galaxy 3-48C Installation Manual

Memory

Memory
The Galaxy 3 Series control panel is fitted with a memory chip with its own battery backup on the main PCB.
This allows the panel to retain the system configuration, programming details and the event log for up to a year
when both the mains power and standby battery have been disconnected. The memory backup battery must
be kept in place to retain the memory during a mains failure. Re-apply power, this is known as a warm start.
To completely erase the system memory and return to the default settings, place a piece of thin card between
the retaining clip and the memory backup battery then remove all power to the PCB for one minute. Re-apply
power and remove the card. This is known as a cold start.
The memory backup battery shoud be replaced every 5 years.
CAUTION: There is a risk of explosion if the battery is replaced by an incorrect type.
Dispose of used batteries according to the instructions.
CAUTION: Do not overstress the retaining clip when removing and installing the backup
battery. The clip must maintain a firm pressure on the backup battery at all times.

RS485 Data Communication Bus (AB Lines)

Communication between the Galaxy control panels and the modules attached to the system takes place on the
AB lines. The communication protocol is RS 485 format. The control panel constantly monitors the modules
attached to it. A break in the communication from any of the modules generates a module tamper alarm

RS485 Wiring Configurations

The system must be wired in a daisy-chain configuration. That is the A line from the previous module is
connected to the A terminal of the current module and then on to the A line of the next module.
The RS485 (AB) line must have a 680 Ω resistor fitted across the A and B terminals of the last module on the
line. If two lines are connected, both ends must be terminated with 680 Ω resistors and the appropriate link
(LK3 or LK5) removed.
Each AB line can run in two directions from the control panel.
• Remove link LK3 (RS485 line1) or link LK5 (RS485 line2).
• Run two lines from the A and B terminals of the line.
• Terminate both Ends of Line (EOL) with a 680 ohm resistor.
NOTE: It is permissable to have different configurations on each line. For example, line 1 - Daisy chain;
line 2 - twin AB daisy chain.
Galaxy
Control
Panel
A
680 Ω
B
Fit LK3/LK5 on PCB
Figure 2-8. Daisy Chain Configuration
Galaxy 3 Series Installation Manual
Keypad/Keyprox
OR
Module
B
A
2-10
A B
680 Ω EOL