RC224ATL/224ATLV
6.0 Operation
EmbeddedModem Family
6.4 Data/Fax Auto Answering
establish the appropriate connection, and inform the DTE of the caller type with
the following result codes:
Numeric
Verbose
Description
13 (0Dh)
DATA
DCE sends this result code only during auto answering or
when DCE has connected as a data modem.
15 (0Fh)
FAX
DCE sends this result code only during auto answer
mode when DCE has connected as a fax modem.
It is assumed initially for auto answer operation that the DTE is running the
fax communication package.
It is impractical to force the fax package to use the same options selected by
the data package. Therefore, some method must be provided to allow the DTE fax
package to restore the DCEs registers after the DCE has connected as a data
modem. The DCE accommodates this by automatically entering the on-line
command mode after connecting. After the DTE receives the DATA result code, it
can then send any necessary AT commands to the DCE. The DCE will wait in the
on-line command mode and delay sending the “data” connect message until the
DTE sends an ATO command. After sending the ATO command, the DTE then
transfers control to the data communication package.
For DTEs running separate data and fax packages in a foreground/background
configuration, a method is provided to allow the fax package to regain control
after the data connection has terminated during auto answer mode without
requiring changes to existing data packages. The RC224ATLV accommodates
this through the use of the data carrier detect (DCD) indicator. Initially, in auto
answer mode DCD will be off. When connected in data mode, the DCE will turn
DCD on. When the data connection is terminated, the DCE will turn DCD off
again. The fax package, running in the background, can poll DCD (160450
modem status register bit 7) to ascertain the data connection status. The DTE
must send AT&C1 to cause DCD to operate in this manner.
During auto answer mode, when the caller is a fax machine, the DCE will
behave as a normal fax DCE (as defined by +FCLASS=1) with the following
exceptions:
1. The transmission of the fax 2100 Hz answer tone will be delayed by the
time needed to determine that the caller is a fax machine (S9 seconds).
2. The DCE sends FAX message at the data mode DTE rate (as defined by
the previous AT command autobaud rate) and automatically sets
+FCLASS=1 after detecting that the caller is a fax.
3. After the answer tone is sent and the DCE enters the V.21 transmit mode,
the CONNECT result code will be sent at 19,200.
During auto answer mode, if the DCE determines that the caller is not a data
modem nor a fax machine, then DCE will send the NO CARRIER result code, go
on-hook and remain in data mode.
Table 6-2 describes a procedure to configure a terminal being called by a 1200
bps data modem. Table 6-3 describes a procedure to configure a terminal being
called by a fax machine with or without calling tone.
D224ATLVDSC
Conexant
6-9
CONEXANT [ CONEXANT SYSTEMS, INC ]
