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Owner’s Manual Rev 1.0 Page 36 of 36
Data Terminal Ready (DTR)
DTR indicates that the DTE is ready to transmit and receive data. It also
acts as a hardware ‘hang-up’, terminating calls when switched high. The
signal is active low. You can define the exact behaviour of DTR with an AT
command.
The DTR line can also be used to switch on the modem when activated for
0.2 seconds. The DTR line must be deactivated prior to switching off the
modem to ensure it switches off (powers down) correctly.
Data Set Ready (DSR)
An active DSR signal is sent from the modem to the application (DTE) to
confirm that a communications path has been established. DSR has two
modes of operation, which can be set using the AT command AT&S.
Data Carrier Detect (DCD)
DCD indicates that the DCE is receiving a valid carrier (data signal) when
low. You can define the exact behaviour of DCD with an AT command.
Ring Indicator (RI)
RI indicates that a ringing signal is being received by the DCE when low.
You can define the exact behaviour or RI with an AT command.
2.6 Real Time Clock
The TT4031 (SE-GM29) contains a real time clock (RTC) to maintain
accurate timekeeping and to enable “timestamping” of messages.
The RTC is powered when d.c. power is connected to the modem AND the
modem is switched on. If the d.c. supply fails, a stored energy device
within the TT4031 (SE-GM29) provides back-up power to maintain the RTC
for at least 12 hours.
2.7 Software Updates
It is possible and sometimes necessary to update the TT4031 (SE-GM29)
software. Updates must be carried out by a Sony Ericsson approved
technician. Please contact your supplier for details (see “Service and
Support”).