The escape sequence causes the modem to go to the off-line command state from the on-line data state. After this escape sequence, the modem can accept user's AT commands. The escape sequence consists of three escape code that is defined by S-Register 2 (default value: decimal 43(+)).
Do not enter any character before and/or after the "+++" for a guard time specified by S-Register 12 (default: 1 second). The duration between escape codes must also be within the guard time. After the modem recognizes a valid escape sequence, an "OK" result code is returned. If an escape sequence is valid, the escape code is transmitted to a remote modem. The ATO command is used to go back to on-line data state.
For example:
ATD 0123456 [enter]
CONNECT 19200
[data] [----]
( 1 sec pause )
+++ (Without 1 sec pause between escape codes)
( 1 sec pause )
OK (On-line command state)
ATH0 [CR] (Disconnect the line)
OK
This command re-executes the previous command processed by the modem. This command will be useful to re-dial without entering a dial string when a line is busy or unanswered. This command is not preceded by "AT", or followed by [Enter].
This command instructs the modem to return its product identification information.
This command resets the modem and recalls the stored configuration as defined at power on time.
This command reloads the factory default profile.
This command is only included for compatibility and performs no function. The value is written into S-Register 21.
This command displays the current active configuration, stored user profiles, and the first four stored telephone numbers. Applications may change these profile.
If the modem's non-volatile memory is detected as defective by the modem's NVRAM test, the modem will display NVRAM FAILED OR NOT INSTALLED
This command stores the current, active configuration including S-Registers into non-volatile memory as stored user's profile 0 or 1. Storable parameters can be viewed by &V command. Stored parameters can be recalled into active configuration by Zn command or at power on.
This command selects which of two user's profiles will be loaded into the active configuration following Power on Reset.
This command stores up to 4 telephone number dial strings into one of 4 non-volatile memory locations specified by n. This stored phone number can be used for later abridged dialing with the DS=n command.
n: Entry number (range 0-3)
x: dial string less than 45 digits (including dial modifiers)
This command controls the modem speaker volume when the speaker is turned on.
This command selects when the modem speaker will be on or off.
The modem will go off hook, transmit the answer tone, and wait for a carrier from the remote modem.
This command is included for compatibility only and has no effect other than returning a result code.
Puts the modem into origination mode, allowing it to work as an automatic dialer for connection to another modem. The string n contains the telephone number and the following optional "dial modifiers".: The string n must be less than 45 characters excluding spaces, hyphens, and parenthesis, which can be used for clarity.
This command provides switch hook control.
This command forces pulse dialing until the next T dial modifier or T command is received. Sets S-Register bit 5.
This command forces DTMF dialing until the next P dial modifier or P command is received. Clears S-Register bit 5.
This command determines whether the modem hangs up when it receives a long space signal (greater than 1.6 seconds) from the remote modem. If enabled, the modem will send a 4 second space signal to the remote modem before hanging up.
The modems.com 28.8(V.34) / 14.4 Kbps Data/FAX Modems can determine the speed, parity, and stop bits from the serial port connection. The modem automatically detects the serial data speed between 300 and 115,200 bps with the following formats:
Data Length Parity Stop Bits Total Length
7 None 2 10
7 Odd 1 10
7 Even 1 10
7 Mark 1 10
7 Space 1 10
8 None 1 10
8 Odd 1 11
8 Even 1 11
The modem also has the capability of automatically adjusting the baud rate to the internal serial port to physical carrier speed. The user application must adjust the baud rate of the internal serial port to it by detecting carrier speed after CONNECT xxxx message. This command setting is valid for reliable (error corrected) link and normal mode connections. The baud rate adjust feature is always active for direct mode connection.
This command controls the behavior of the DCD (Data Carrier Detect) signal of the internal serial port.
This command controls the modem response to the serial port's Data Terminal Ready (DTR) signal. This command interprets the ON and OFF transitions of the DTR signal from the DTE in accordance with the parameters as defined by n.
This command determines how the modem controls data flow between the system and the modem. For example, if the speed between the system unit and the modem is 19200 bps, and the speed between the local and remote modem is 2400 BPS, the transmit buffer of the modem is likely to be overflow when the system is sending large amounts of data. To prevent an overflow and subsequent loss of data, the modem either sends a XOFF character or drops the CTS signal to signal that the system should stop data sending. When enough space is available in the modems transmit buffer, the modem either sends a XON character or raises CTS to signal that application could resume data sending.
For binary data transfer CTS/RTS flow control should be selected since the modem cannot distinguish the user's data from XON/XOFF characters. Flow control is not used for direct mode connection.
Determines the DTR operating mode. The modem treats the &M command as a subset of the &Q command. This command is used to choose between asynchronous, synchronous, or direct dial modes while the modem is in the command state. Only Asynchronous mode is supported., and between synchronous and asynchronous data flow when a connection is established.
This command determines how the modem controls CTS (Clear to Send). CTS operation is modified if hardware flow control is selected.
Data Set Ready Control
Selects the source of the transmission clock for the synchronous mode of operation. The parameter value, if valid, is written to S27 (bits 4 and 5). In asynchronous mode, the transmission and receipt clocks are turned off.
This command enables and/or disables software flow control using XON/XOFF, between your modem and the remote modem. During a reliable (error corrected)reliable connection this setting is ignored.
This command determines the split-speed DCE/DTE interface for applications such as ViewData terminals, which require a transmit speed of 75 bps and a receive speed of 1200 bps at the DTE interface.
This command determines which direction, transmit or receive, has the 75 bps channel and which has the 1200 bps channel. This command is only valid if the "Split-Speed Operation" command has been executed.
These commands control the responses to commands issued the modem.
En (Command Echo)This command determines whether the modem echoes characters back to the DTEsystem, when in command mode.
Used to enable and disable return results codes to the DTE.
This command determines the format of the return result code if result codes are enabled (see Qn command). For example, the long form (word format) returns "OK" or short form (numeric format) returns "0". The long form format result code is preceded and terminated by both carriage return and line feed characters. The short form format result code is terminated by a carriage return character.
This command determines which set of responses and calling characteristics are used. This command determines whether the modem recognizes dial tones and busy tones, and what kind of result code should be enabled. When n is 0, 1, or 3, the modem waits for the time specified by S-Register 6 (default 2 seconds) after going off-hook, then dials regardless of the presence or absence of dial tone. Blind dialing is used in some countries where dial tones could very from central office to central office, or for certain PBX's which generate unique dial tones.