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2.6. Modem Status Indicators
Two LED indicators are used for displaying operation mode status or emergency situation. Indication can
be controlled via AT command "AT^SLED". By default, the value is AT^SLED=2,50. LED indication modes for
displaying operation modes are given in Table 2.6.1.
Table 2.6.1
Operation mode indication (green LED)
Status display mode
Schematic LED signals
representation
Operating mode
Off
○
The modem is switched off or at fault condition;
power-saving mode; "ALARM" mode
500 ms on / 500 ms off
●●●●●○○○○○
The modem is not registered to the network
50 ms on / 3990 ms off
●○○○○○○○○○○○○○...○
The modem is registered on the network
50 ms on / 1990 ms off
●○○○○○○...○
GPRS connection established / Data
transmission in progress (GPRS)
250 ms on / 250 ms off
●●●○○○
Programming mode, menu mode
50 ms on / 990 ms off
●○○...○
Voice call, CSD
Table 2.6.2
Fault condition indication (red LED)
Status display mode
Schematic LED signals
representation
Fault description
Continuously lit
●
Wrong input voltage
0,25 s on / 0,25 s off /
0,25 s on / 1 s off
●
○
●
○○○○
GSM module failed to start
0.5 s on / 0.5 s off
●
○
Wrong module power
Emergency situations are described in section 4 of this document.
