ADTRAN DSU IV ESP, Руководство пользователя

Страница: 59 / 194

Chapter 5. Configuration Overview
61204011L1-1 DSU IV ESP User Manual 5-5
AT Commands
The DSU IV ESP can be configured and controlled with in-band AT
commands from an asynchronous DTE port just as modems are.
To exit the data mode and enter the command mode, the
asynchronous DTE device must transmit a proper escape sequence
of three pluses (+++) to the DSU IV ESP. A specified time delay
must occur between the last data character and the first escape
sequence character. This is the guard time delay, and it can be
changed by writing a value to the S12 register. The default value for
the guard time is one second. For a valid escape sequence to occur,
the DTE must transmit the escape code character three times in
succession with delay between each character being less than the
guard time.
Once the command mode is entered, AT commands can be
transmitted to the DSU IV ESP to configure most of the options or
initiate tests to check both the DSU IV ESP and the network
connections. All command lines must begin with the AT character
set in either capital or lower case letters.
The command line may contain a single command or a series of
commands after the AT attention code. When a series of commands
is used, the individual commands may be separated with spaces for
readability. The maximum length for a command line is 40
characters. Each command line is executed by the DSU IV ESP
upon receipt of a terminating character. The default terminating
character is a carriage return (ASCII 013), but it can be changed by
writing a different value to register S3.
Before the terminating character is transmitted, the command line
can be edited by using the backspace character (ASCII 008) to erase
errors so the proper commands can be entered.
Not all parameters can be selected using these commands. Valid com-
mands are listed in Appendix B, AT Commands on page B-1.