CEP Terminals GT910 G, User Manual

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5 Operation
5.1 Switch ON the modem
NOTICE
To ensure correct operation of the Terminal, please ensure that a SIM Card has been inserted into the
terminal prior to switching it on.
Do not insert a SIM card into the device while it is switched on. If you find out that the device is switched
on but missing a SIM card, first switch off the modem and then insert the SIM card. Note that the device
does not have a SIM card detect feature.
There are two ways to switch on the modem, once power is applied:
 assert TO_IN to high level for > 5s
 activate the RS232 control line DTR for >0.2s
The modem is fully operational after 4 seconds. Logging onto a network may take longer than this and is
outside the control of the modem. The modem can be configured to start up at the time power is applied
by permanently tying power connector signals TO_IN (pin 4) and VCC (pin 1) together.
DTR must be cycled from low to high.
Although this will not be an issue in almost all typical applications of the modem, there are a few cases in which
the modem might not recognize the power up signal. This is no failure of the modem itself, the same would
apply to almost any electronic device that provides a separate “power on” or “reset” signal.
Possible cases are the following:
 Large capacitors in your power supply which will lead to slow leading and falling edges (issue does not apply
with modern stabilized switching regulator power-adaptors) AND TO_IN tied in parallel to VCC (instead of
separate dedicated digital signal)
 Slow analogue signals used to assert TO_IN
 TO_IN signal not before VCC
If you are in doubt, please
 Use the mains power adapter that is provided by your distributor and is known to work properly with your
modem.
 Make sure that your signal and system design is according to the above.
 Consult our support team that will be more than happy to assist you.
The TO_IN signal requires a positive “edge” (a sharp” signal transition from low to high)
to turn the modem on. This transition should be a rising signal from 0V (GND) to VCC, or
at least a large fraction of that voltage range, and must be applied at the same time as
VCC or after it.
Very slow transitions (significantly slower than many milliseconds) or very small
transitions (e.g. only few volts instead of 0V to VCC) will not turn on the module (since
they are not considered to be a “positive edge”).