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CHAPTER 3
Using the RTU
16
This completes the installation of your addIT RTU. If one of the
I/O
connectors is left unused, use the cap specially provided to protect
it against moisture and dust. Be sure to make a note of the follow-
ing information because you’ll need it when you configure the
device in the software:
• Serial number for each RTU
•Type of sensors connected to each RTU
More about the LED tool
The LED tool allows you to rapidly check the status of an addIT
RTU. After you insert the LED tool into the POWER connector, the
unit waits up to two seconds and then sends a broadcast frame. If a
nearby listening station or receiver decodes the frame, it will
answer back—this may take up to 10 seconds. When an answer is
received, the LED tool lights up for about 4 seconds. After another
few seconds, the LED lights up one or more times, depending on
the number of stations/receivers that answered to its broadcast
frame.
Note: addIT RTUs do not respond to a broadcast frame, only
remote stations (A730MD) and base stations (A730SD or
A720B).
In addition, the LED always blinks briefly at 0.5 second intervals to
indicate that the unit is alive and the internal battery has enough
energy to operate. If the blinking interval lengthens to 2 seconds,
the battery has become undercharged (that is, under 5.6 volts but
over 5.2 volts)—this is called the
misery
state. In this state, an
addIT RTU reduces its activities to a minimum. The radio unit is
switched off, the sensor sampling ceases, and no data is stored in
the internal memory. Only the internal real-time clock is maintained
and the power management functions are performed.
If the battery level drops below 5.2 volts, the system switches com-
pletely off, effectively decoupling itself from the battery in order to
protect it. In this case the LED tool stays permanently off. An addIT
RTU in such a situation will restart only after connecting it to an
external power supply (even a solar panel under low light condi-
tions).
Note: New addIT RTUs are delivered with their internal batteries
unformatted, meaning they are completely discharged, and
you should install them only on sunny days. The battery will