Synxcom SM9234D, User Manual

Page: 170 / 216

AT Commands
Page 170
a. A Class 1 command is received while in Class 2.
b. A Class 2 command is received while in Class 1.
c. A Class 1 or Class 2 action command is received while in data modem
mode.
d. A Class 2 read-only parameter is given the “=” form of a +F command
(e.g., AT+FAXERR=5).
e. A Class
Serial Port Speed and Flow Control
During fax mode, the DTE-DCE port speed is 19200 bps.
The DCE provides a speed buffer of 1024 bytes and provides the DC1/DC3
(XON/XOFF) or RTS/CTS method of controlling the data into the buffer. This
flow control is controlled by the &K3 or &K4 command.
This method of data flow control is available only for DTE to DCE direction of
data. There is no provision for data flow control from DCE to DTE.
Data Stream Termination
The DCE exchanges streams of data with the DTE while executing data transfer
commands. These data streams use the termination described in ISO 2111.
The ASCII <DLE> character (016) is used as a special character to shield special
characters. The <DLE><ETX> character pair (<106><003>) is used to mark the
end of a stream. The following patterns are used:
any data...<DLE><ETX> end of stream
any data...<DLE><DLE> single <DLE> in data
any data...<DLE><any byte> delete <DLE><any byte>
DTE to DCE Streams
The DCE filters the data stream from the DTE, and removes all character pairs
beginning with <DLE>. The DCE recognizes <DLE><ETX> as the stream
terminator. The DCE recognizes <DLE><DLE> and reinserts a single <DLE> in
its place.
The DTE must filter stream data to the DCE, and insert extra <DLE> characters
ahead of data.