Product data

USRobotics
Command Reference
Fax Class 1 and Fax Class 1.0 Commands - 112
generates the CONNECT message to the DTE and waits for further data from the
DTE while transmitting NULLs to the remote. If more data is received before five
seconds elapse, the modem continues to transmit the data as described in the
previous paragraph. If five seconds elapse and no data is received from the DTE,
the modem drops carrier, goes on-hook, and generates the ERROR result code.
Fax Data Reception
Fax data reception is initiated using the AT+FRM=<mod> command. After this
command is issued, the modem looks for carrier in the modulation scheme
specified by the parameter n. If no carrier is detected before the period of time
specified by register S7 expires, the modem generates the NO CARRIER
message and returns to command mode. If a V.21 carrier is detected when a high
speed carrier is expected, the modem generates the +FCERROR message and
returns to the command mode. If the specified carrier is detected, the modem
generates the CONNECT message and enters the data receive mode.
While in data receive mode, the modem receives data from the remote, adds start
and stop bits, and handles <DLE><chr> character pairs before passing the data to
the DTE. The modem prefixes each <DLE> character with another <DLE>
character before sending it to the DTE.
If the modem detects a receive buffer overflow condition, it stops receiving from
the remote until there is room in the receive buffer. The modem informs the DTE
of the buffer overflow after it sends to the DTE the last character that was stored in
the buffer before the overflow occurred.
If the modem receives any character from the DTE after the +FRM command
(except flow control characters if software flow control is in effect), or if the modem
detects a high-to-low transition of the DTR signal while &D1 is in effect, it sends
<DLE><ETX> to the DTE, generates the OK result code, and returns to command
mode. The receive buffer is cleared and all data received from the remote is
discarded. If loss of DTR is detected while &D2 is in effect, the modem goes on-
hook, sends <DLE><ETX> followed by OK result code to the DTE, and returns to
command mode. If the modem detects a DTR drop while &D3 is in effect, the
modem performs a warm reset.
Commands and Parameters
Mode Entry Commands
+FCLASS=1 - Select Facsimile Class 1 Mode
+FCLASS=1 selects the Fax Class 1 Mode. The Fax Class 1 Mode commands
and responses described in this section are applicable when command
+FCLASS=1 as shown in Table 5-1. (See +FCLASS for the definition of the
FCLASS command.)