Northern UTA220/UTA220k - Manual (Page 65)

UTA220/UTA220k
8-1
AT Command Operation
Chapter 8
AT Command Operation
This chapter provides information on how to use AT
commands to operate and configure the TA via a data port.
The UTA220 AT command set is shown in Appendix C.
AT COMMAND STATEMENT
The TA communicates with a DTE asynchronously whenever
the corresponding DTE port is configured for AT command
mode. When the TA is powered up, any DTE port configured
for AT commands enters command mode. AT commands can
then be used to configure and control the TA. The command
statement is typed using the DTE keyboard and temporarily
resides in a section of memory called a buffer.
The command statement must be written in a specific form so
the TA recognizes and follows the instruction. The command
statement begins with the letters AT and is followed by one or
more commands, which can each consist of a sequence of
keyboard symbols, such as & and %, letters, numbers, and is
followed by a return or end-of-line character.
AT Command Mode
AT commands can only be issued when the DTE port is
configured for AT command mode. Normally, the DTE port is
in AT command mode whenever it is off-line. After the TA
establishes a connection with another TA and goes into on-line
data mode, characters sent to the TA by the DTE are interpreted
as data (not as commands) and are transmitted to the remote
TA.
If the DTE port is configured for DIALER CMDS = NONE,
AT commands are not accepted in any mode.
ESCAPE SEQUENCE: + + +
If the TA is in asynchronous data mode, the escape sequence
can be sent to return the TA to the command mode and remain
on-line. The escape sequence consists of a pause (normally 1
second), three escape characters, and then another pause. The
default escape sequence characters are: + + +.
The escape sequence character is set by the S2 command and
can be changed. The escape sequence can also be disabled to
prevent false escapes into command mode.
After entering the escape sequence, the TA returns to AT
command mode, but does not hang up or break the connection
with the remote TA. AT commands can now be entered to the
TA. The ATO command returns the TA to the data mode.