User's Manual

CHAPTER3
Understandingconnectors
16
connector contains four pulse counter inputs, one analog input, and a
sensor supply voltage output. Figure 6 illustrates the individual pins of
an I/O connector.
Figure 6. Pins on the I/O Connector (Top View)
ThePOWERConnector
The RTU also has a POWER connector, which allows for:
• External supply (battery or any DC source from 5.6 to 10 volts)
• External charge supply (either a solar panel or an AC adapter) if
an internal rechargeable battery is used
• Communication over serial lines, at 19200 baud
Figure 7 illustrates the connections available at the POWER connector.
Figure 7. A724 POWER Connector (Top View)
 WARNING The serial line is 3-volt CMOS compatible; therefore, a special adapter
cable must be used to reach the RS-232 levels. Also, if an external
battery is used, the internal battery must be disconnected.
You might want to use the POWER connector with something other
than the standard configuration. For example, if you want to connect
an external battery to the RTU, disconnect the internal battery and
use the configuration shown in Figure 8.
SBAT
CNT3 CNT0
CNT1
AN0
GND
CNT2
7
3
6
5
1
2
4
Ext
Power
TxD
RxD
Ground
Battery
5
2
4
1
3