AL2094S Designers Guide
Doc. No. DG_2094E
Altec Electronic AG
Seite 11 / 30
2.3 Data
Mode
Data mode exists when a telephone line connection has been established between modems
and all handshaking has been completed.
2.3.1 Speed Buffering (Normal Mode)
Speed buffering allows a DTE to send data to, and receive data from, a modem at a speed
different than the line speed. The modem supports speed buffering at all line speeds.
2.3.2 Flow
Control
DTE-to-Modem Flow Control.
If the modem-to-line speed is less than the DTE-tomodem
speed, the modem supports XOFF/XON or RTS/CTS flow control with the DTE to ensure
data integrity.
2.3.3 Escape Sequence Detection
The +++ escape sequence can be used to return control to the command mode from the
data mode. Escape sequence detection is disabled by an S2 Register value greater than
127.
2.3.4 BREAK
Detection
The modem can detect a BREAK signal from either the DTE or the remote modem. The \Kn
command determines the modem response to a received BREAK signal.
2.3.5 Telephone Line Monitoring
GSTN Cleardown (V.90, V.34, V.32 bis, V.32).
Upon receiving GSTN Cleardown from the
remote modem in a non-error correcting mode, the modem cleanly terminates the call.
Loss of Carrier (V.22 bis and Below).
If carrier is lost for a time greater than specified by
the S10 register, the modem disconnects (except MNP 10).
2.3.6 Fall
Forward/Fallback
(V.90/V.34/V.32 bis/V.32)
During initial handshake, the modem will fallback to the optimal line connection within
V.90/V.34/V.32 bis/V.32 mode depending upon signal quality if automode is enabled by the
+MS or N1 command.
When connected in V.90/V.34/V.32 bis/V.32 mode, the modem will fall forward or fallback to
the optimal line speed within the current modulation depending upon signal quality if fall
forward/fallback is enabled by the %E2 command.
2.3.7 Retrain
The modem may lose synchronization with the received line signal under poor or changing
line conditions. If this occurs, retraining may be initiated to attempt recovery depending on
the type of connection. The modem initiates a retrain if line quality becomes unacceptable if
enabled by the %E
command. The modem continues to retrain until an acceptable connection is achieved, or
until 30 seconds elapse resulting in line disconnect.
2.3.8 Programmable Inactivity Timer
The modem disconnects from the line if data is not sent or received for a specified length of
time. In normal or error-correction mode, this inactivity timer is reset when data is received
from either the DTE or from the line. This timer can be set to a value between 0 and 255
seconds by using register S30. A value of 0 disables the inactivity timer.
2.3.9 DTE Signal Monitoring (Serial DTE Interface Only)
DTR#.
When DTR# is asserted, the modem responds in accordance with the &Dn and &Qn
commands.
RTS#.
RTS# is used for flow control if enabled by the &K command in normal or error
correction mode.
