4.3.1 Power Up Device
To verify that an End Device is working before deploying remotely, install batteries and
power it on right next to the Coordinator. When the End Device is powered on, it will
search for the Coordinator in all 16 channels reserved for IEEE 802.15.4 (channel 11
through 26) by sending request packets. While it’s searching, the blue LED on the End
Device blinks every second. Once the Coordinator responds to the End Device request,
the LED will blink only when the End Device sends data to the Coordinator (default is
every 10 seconds). If the Coordinator is not powered on or it’s out of reach, the End
Device will keep searching until the batteries discharge in roughly 36 hours.
Once the Coordinator responds back to the End Device it will include its network number
in the response packet called Beacon. At this time the End Device would know what the
correct Coordinator is (there could be more than one Coordinator responding to the End
Device’s request packet). The channel on which the Coordinator responds back is
automatically picked to be the clearest among all 16 channels and therefore the End
Device starts sending data to the Coordinator on that particular channel.
Once the End Devices and the Coordinator start communicating, make sure to
push DIP switch #1 located on the back of the Coordinator to ON position. This
will lock the Coordinator on the same channel it initially established the
connection.
After the End Device transmits data to the Coordinator, it expects an acknowledgment
packet back from the Coordinator. If the End Device does not receive an
acknowledgment packet back within 50ms, it will go to sleep mode for 2 seconds and
then will retransmits the data. This cycle will be repeated for 10 times and if it still does
not receive the acknowledgment packet back, the End Device takes a longer sleep time
of 3 minutes. After 3 minutes, the End Device retransmits the data every 2 seconds for 4
times and each time it waits for 50ms for an acknowledgment. If it still does not receive a
response back from the Coordinator it will take another 3 minutes of sleep. This last
sequence will continue until the batteries are drained. Through the whole retransmission
cycle explained above the blue LED on the End Device will blink anytime retransmission
takes place.
The data being retransmitted will automatically gets updated as new readings
take place.
If the communication channel is manually selected in the Coordinator, the End
Devices must be power-cycled in order to establish connection over the new
channel. If it’s not possible to power-cycle the End Devices locally, a remote
option is available through the Coordinator’s Web server or Telnet console.
When there are two End Devices with the same Device ID, both will be
transmitting data every second with their LEDs blinking once a second. The
Coordinator will receive data from both End Devices and will display their data
alternately. On the “Readings”, “Chart”, and “Diagnostic” pages of the
Coordinator’s Web server, the phrase “ID” error code will be placed indicating
the conflict. Once the problem is resolved, click on the “Reset Sensor” button
located on the Sensors Parameters page to remove the “ID” error code.
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