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30 536EX Chipset Developer’s Manual
Intel Confidential
Data Mode AT COMMANDS
ATDT 9,444-5555 Automatically dials the telephone number with DTMF tones. After
dialing a ‘9’, the comma (,) causes the modem to pause two seconds
before dialing the rest of the telephone number.
modem 1: ATD; When establishing a manual-to-manual connection, the designated
modem 2: ATA originating modem should receive the ATD command from its DTE
just before the designated answering modem receives the ATA
command from its DTE. It is important that the time between the ATD
and ATA commands is less than 2 seconds.
AT-C1DT 123 Causes the modem to dial the telephone number 123 and immediately
start sending a data calling tone. Calling tone can then be detected by
the remote voice mail system. After detecting the calling tone, the
remote system can change to data mode and start the data modem
connection handshake.
3.6 Online Command Mode [Escape Codes, On]
After establishing a connection with a remote modem, the DTE sends the appropriate escape
sequence to the DCE, which causes the DCE to enter the online command mode. The online
command mode is used to send AT commands to the DCE while the DCE is still connected to the
remote modem. The supported escape sequences are described in Section 3.10, “AT Escape
Sequences” on page 38. To re-enter the online data mode, use the ATOn command.
Example:
1 second +++ Hayes Escape Sequence. Guard times (in which the DTE does not send
1 second data to the DCE) of 1 second are needed before and after the three
escape characters ‘+’.
+++AT<CR> TIES (Time Independent Escape Sequence).
ATO Causes the modem to re-enter online data mode.
3.7 Hanging Up [Hn, S10, Zn, &D2]
A modem connection terminates when the modem hangs up or when the remote modem transmit
carrier is off longer than the duration specified in S-register S10. To hang up, the DTE typically
sends an escape code sequence that causes the DCE to enter online command mode. Upon
receiving an ‘OK’ message, the DTE sends either ATH or ATZn to the DCE. When the AT&D2
command is used, the modem goes on-hook (hangs up) after an on-to-off transition of the DTR
occurs.
Note: The ATZn command causes the DCE to hang up and re-initialize itself to the user profile specified
by ‘n’.
3.8 Modem-to-Modem Connection Data Rates
The data rates differ for each data mode selected. The 536EX chipsets either default to V.90 or V.92
mode depending on the driver version. For non-ISP connections, the chipsets fall back to V.34
mode. The modem defaults to whatever mode is issued by the +MS=m command (see the
supported modulation types on Table 16 on page 35).