The iMetos3.3 can operate in three different working modes:
1. Logging and transmitting (normal mode)
2. Logging, not transmitting (gathering mode)
3. No logging, no transmitting (sleeping mode)
The standard working mode is the normal mode in which the station measures and communicates regularly.
If the battery voltage drops below a threshold (6.1V), the station changes to gathering mode. The station measures regularly, but modem communication is deactivated.
If the battery voltage falls below yet another threshold (5.4V), the station changes to sleeping mode. Both measurements and communication are deactivated.
A station in gathering mode automatically changes back to normal mode if the voltage is high enough again.
If the station is in sleeping mode, also the measurement of the battery voltage is deactivated. Therefore the station has to be activated manually by pressing the connect button (see picture below) on the board in order to change back to normal mode. First the SMS are checked, then the communication with the server is started.