Issuing Commands - AT&T 7400B Plus User Manual

CHAPTER 3: CONFIGURATION AND OPERATION
Page 3-2

ISSUING COMMANDS

AT Command Line Prefix
The following paragraphs describe the elements of a command
line and how the 7400B Plus responds to a command line when it
is issued.
All commands issued to the 7400B Plus must begin with the letters
''AT'' or ''at'' with the exception of the ''A/'' command which is
discussed later. The command line prefix must be entered as
either both uppercase or both lowercase letters (that is, at and
AT will work, but aT and At will not).
The letters ''AT,'' also known as the ATtention command, alerts
the 7400B Plus to expect one or more commands to follow. The
7400B Plus examines the command line prefix to determine the
communications rate of the terminal equipment as well as its
parity setting. The 7400B Plus automatically adjusts the speed
and parity settings and uses the setting until another ''AT''
command is received, or until the 7400B Plus is powered down.
Formats supported by the 7400B Plus are shown in Table 3-1.
TABLE 3-1
CHARACTER FORMATS
Data Bits Parity
7 even or odd
7 mark or space
8 none
All of these parameters may be changed on the local terminal
device as needed. The 7400B Plus will adjust to match the speed
and parity of the local terminal device when it receives an ''AT''
command.
If you connect to a remote system and your screen shows a
series of nonsense characters (also referred to as ''garbage''),
chances are that you need to adjust the speed or parity on the
terminal to match the settings of the 7400B Plus.
DEFINITY Communications System
7400B Plus Data Module
User´s Guide
Stop Bits
1
1
1