Multi-Tech Systems MT5634SMI V.92, MT5634SMI V.34 manual Modes of Interaction, AT Command Mode

Chapter 3 – Fax Class 2 Commands

Transmitting Modem			Receiving Modem
Line #	Command/response	Comments	Line #	Command/response	Comments
T14	<page data>	Send T.4 formatted page data	R16	<page data>	Receive T.4 for-
					matted page data
T15	<DLE><EOP>		R17	+fps:1000,0,0,0	1000 lines
					received
T16		This is the last page	R18	+fet:2	This is the last
					page
			R19	ok
			R20	AT+FDR	Send page
					received OK
					message
T18	+fhs:0	Send one page done	R21	+fhs:0	Receive one
					page done
T19	ok		R22	ok

We can now use the example to help explain the terminology for the fax command extensions.

Modes of Interaction

The modem has three modes of interaction: AT command mode, command execution mode, and data transfer mode.

In AT command mode, serial data sent to the modem is interpreted as commands when preceded by the characters AT.

Command execution mode follows AT command mode when an action command, such as a dialing command, is sent to the modem. The modem responds to an action command by displaying responses that indicate the progress of the command and also information received from the remote fax modem. If serial data is received at that point, the fax is aborted and the phone call terminated.

Data transfer mode begins after a +FDT or +FDR command is entered from AT command mode, the command is executed, and a CONNECT response is given. When a +FDT command is used to enter data transfer mode, the serial data sent to the modem should be image data for the page being transmitted, as specified by the ITU-T T.4 standard. When a +FDR command is used to enter data transfer mode, the serial data received from the modem should be image data for the page currently being received.

AT Command Mode

In AT command mode, both regular AT commands and fax AT commands can be sent. Regular AT commands are used to control data modem functions and functions common to both modem and fax operation, such as dialing (ATD) and answering (ATA). Fax AT commands begin with the characters +F followed by a command name followed by either “?” if reading a parameter,=“”followed by a parameter value if setting a parameter, or “=?” ifinquiring the valid values of a parameter. Any AT command that follows a fax AT command must be separated from it by a semicolon.

Fax AT command types. There are two types of fax AT commands: action commands and parameter commands. Action commands initiate a sequence of events that change command mode to command execution mode, and therefore do not execute instantaneously. Because of this mode change, an action command must be the last command in a command line. In contrast, parameter commands execute immediately; therefore more than one can appear in the same command line.

Multi-Tech Systems, Inc. SocketModem MT5634SMIxx Reference Guide (S000263C) 50