Northern UTA220/UTA220k manual Chapter AT Command Operation, At Command Statement, AT Command Mode

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.

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