Multitech Modem Module MT3334SMI, Developer'S Manual

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Chapter 3 - Class 1 Fax Commands
MT3334SMI 37
Flow Control
XON/XOFF flow control is used by the ModemModule to match the PC-to-modem data rate to the
line signaling rate. XON/XOFF flow control is mandatory and RTS/CTS flow control is optional per
the Class 1 standard. There is currently no Class 1 command for setting the flow control method,
and no means to read the current flow control method in use. The PC is responsible for matching the
modem's default flow control method.
Result Codes
Your Class 1 ModemModule can respond with the basic set of result codes (OK, CONNECT, NO
CARRIER, and ERROR) with only minor differences in meaning for fax mode.
If the modem detects a data carrier or tone other than that specified by the +FRM or +FRH
command, it sends a CONNECT ERROR (+FCERROR) result code to the PC, then returns to
Command mode. This will allow the PC to recover by reconfiguring the modem to define the
unexpected signal. The CONNECT ERROR message has the formats +FCERROR (verbose) or +F4
(terse).
Sample Sessions
This section provides Class 1 Fax send and receive handshaking examples.