AOpen FM56, Manual, Page: 87 / 127

4.1 FAX I/O PROCESSING
The fax I/O interface supports asynchronous serial and parallel interfaces. The interface
rate is 19200 bps. 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 commands are identified in Table 4-1.
Table 4-1. Fax Class 1 Commands
Command/Parameter Function
+FCLASS=<class> Select, read or test service class
+FAE=<value> Auto answer enable
+FTS=<time> Stop transmission and pause
+FRS=<time> Wait for silence
+FTM=<mod> Transmit data with <mod> carrier
+FRM=<mod> Receive data with <mod> carrier
+FTH=<mod> Transmit HDLC data with <mod> carrier
+FRH=<mod> Receive HDLC data with <mod> carrier
+FAR=<off/on> Adaptive reception control
+FCL=<time> Carrier loss timeout
+FDD=<value> Double escape character replacement control
+FIT=<time>, <action> DTE inactivity timeout
+FPR=<rate> Fixed DTE Rate
+FMI? Report manufacturer ID
+FMM? Report model ID
+FMR? Report revision ID
+FLO Flow Control
+IFC Local DTE-modem flow control (see +IFC in 3.2.2)
A Answer (see A in 3.2.3)
D <string> Dial (see D in 3.2.3)
H Hangup (see H in 3.2.3)
4.1.4 Fax Origination
Origination of fax calls is made using the ATD command. Upon completion of the dial
function, a calling tone at 1100 Hz is transmitted, with a cadence of 0.5 seconds on and
3 seconds off. The modem automatically enters mode +FRH=3 and sends the