Chapter 6 – fax class 1 and class 1.0 commands, Fax i/o processing, Dte-to-modem transmit data stream – Multi-Tech Systems MT5600SMI-34 User Manual

Page 86: Modem-to-dte receive data stream

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Chapter 6 – Fax Class 1 and Class 1.0 Commands

Multi-Tech Systems, Inc. SocketModem MT5600SMI Developer’s Guide

86

Chapter 6 – Fax Class 1 and Class 1.0
Commands

Fax I/O Processing

The fax I/O interface supports asynchronous serial and parallel interfaces. The character format is 8 bit
data, no parity, and 1 stop bit. Start and stop elements are removed from the transmit data and added to
the receive data. Both transmit and receive data are buffered. Flow control using XON/XOFF or RTS/CTS
is provided.

Unique control character strings are identified, filtered, or reinserted into the I/O data stream. These
control characters and their resultant action are described below.

DTE-to-Modem Transmit Data Stream

Characters Detected

Action Taken

<DLE><data>

Delete <DLE><data> characters.

<DLE><ETX>

Recognize as a string terminator and take appropriate action.

<DLE><DLE>

Replace with single <DLE> character.

Modem-to-DTE Receive Data Stream

Characters Detected

Action Taken

<DLE>

Insert extra <DLE> ahead of <DLE>.

The modem also identifies the end of a frame by inserting <DLE><ETX> into the data stream after the
FCS bytes.

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