LG GDK-20W - Manual (Page 31)

GDK-20W DIGITAL WIRELESS KEY TELEPHONE SYSTEM
33
3.5 SYSTEM WIRING
Battery Back-Up Wiring Installation
The system can be equipped with external batteries for proper operation when local AC power fails. The Back-Up
batteries are connected to the connector(CN3) of the MFB.
The External batteries must provide 24 Volts DC. This is generally accomplished by connecting two 12 volts batteries in a
series arrangement. Battery operation is controlled by the MFB. The MFB will provide charging current(maximum 0.5
amp) to the batteries during normal AC power operation. The MFB will automatically stop the battery operation when AC
power re-applied or low battery voltage detected.
The system operating time by external batteries is depend on several elements as follows, battery charge state, condition
of the batteries, capacity of the batteries, and the system configuration(number of station ports).
The MFB has one industry standard 9 pin RS-232C connector. The RS-232C ports are connected by 9-pin connectors as
shown Figure 3.5.2. Note that the communication settings are 9600bps(Max 38400bps), 8 bit data, no parity bit and 1
stop bit.
The RS-232C port only provides three(3) control signals such as TXD, RXD and ground.
It is recommended that the RS-232C serial cable whose length is below 10 meters is used.
Batteries are connected to the connector(CN3) of the MFB, as shown in Figure 3.5.1.
Warning :
- Carefully check the battery polarity with cable colors(RED and BLUE) when connecting the battery to
system.
- It is recommended to use a fuse(5A @250V) between battery and system.
- Recommended battery capacity is 24V/10AH MF battery. The system will operate more than 5 hours with
this battery.
Figure 3.5.1 Battery Back-Up Wiring
Figure 3.5.2 RS-232C 9-pin Connector Wiring
2(TX)
3(RX)
5(GND)
MFB
RS-232C
Connector
(9pin)
2(RX)
3(TX)
5(GND)
Terminal
RS-232C
Connector
(9pin)
2(TX)
3(RX)
5(GND)
MFB
RS-232C
Connector
(9pin)
3(RX)
2(TX)
7(GND)
Terminal
RS-232C
Connector
(25pin)