Comtrol AT Commands - Manual (Page 155)

AT Commands for CX81801/CX06833/CX81300/CX06827 Modems Reference Manual
102184B Conexant 4-1
4 Fax Class 1 and Fax Class 1.0 Commands
4.1 Fax I/O Processing
The fax I/O interface supports asynchronous serial and parallel interfaces. The character
format is 8 bits 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.
4.1.1 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.
4.1.2 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.
4.1.3 Fax Mode Selection
Fax Class 1 and Fax Class 1.0 commands are identified in Table 4-1. Fax Class 1.0
includes all Fax Class 1 commands.