Technical Manual

6. OPERATION
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LZT 123 7607 R1B
6. Operation
6.1 Switching the GT47 On
The GT47 is turned ON automatically once DC power is applied. If the
GT47 is turned OFF, using one of the methods described in 6.2, the
control terminal can be turned ON again through one of two methods:
• pull signal TO_IN to ground for t >0.2s, then release.
• activate the main RS232 control line DTR, low to high for >0.2s
The GT47 is fully operational after 4 seconds. Logging onto a network may
take longer than this and is outside the control of the GT47.
Note! The GT47 will not switch on if TO_IN is shorted to ground when the dc
supply is applied.
6.2 Switching the GT47 Off
There are two ways to switch off the GT47 as described below.
• Use the appropriate AT command (AT+CFUN);
• pull signal TO_IN to ground for t >0.2s, then release.
6.3 Operating States/LED
The GT47 has a green LED, as depicted below, which is used to indicate
various operating states. These states are described in following table.
Operating state LED
After switching on the GT47 On after 4 s
GT47 switched off or power removed from the module Off
Standby or talk Flashing
No network, network search, no SIM card, no PIN entered On
LED