User guide

Developers guidelines | AT commands
17 June 2010
Switching back to offline command mode
Any of the following will return the built-in modem to offline command mode from
online data mode:
• Loss of connection (NO CARRIER error)
• Loss of the link between the built-in modem and your computer
• Pressing the “NO” button on your mobile phone
• Pulling DTR low (not available when using cable)
Using AT commands during a data connection
To use AT commands while connected to a remote modem in online data mode and
maintain connection with the remote modem, first enter online command mode.
There are two ways to switch from online data mode to online command mode:
• Type the escape sequence “+++” followed by an appropriate AT command. This
command must be selected from the options AT, ATE, ATH, ATI, ATQ, ATV or ATX.
By using this method, an AT function, such as moving into online command mode,
can be performed. For example, switching using
+++ATH<CR>
switches the built-in modem to online command mode. The AT command is
executed, causing the connection to be terminated (hang-up executed). Typing the
escape sequence “+++” without any following command causes the system to wait
one second, switch to online command mode and respond OK;
• Pull DTR low after setting AT&D=1.
Switching from online command mode to online data mode
To return to online data mode while in online command mode, type:
ATO<CR>
Switching from online command mode to offline command
mode
To return the built-in modem to offline command mode from online command mode:
• Use any of the methods described in “Switching back to offline command mode”
above
•Type +++ATH <CR> to switch to online command mode and hang up at once.