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

0.2seconds. 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.

2.6Real 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.

2.7Software 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”).

Owner’s Manual

Rev 1.0

Page 36 of 36