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6.4.2 A
UTOBAUD
The attention code (AT) is analyzed by the modem to determine the transmission speed, parity, and bits
per character used by the DTE. This autobaud process is repeated each time the AT command prefix is
sent.
6.4.3 G
UIDELINES FOR
When typing command statements, note the following:
• The attention code (AT) may be upper or lower case, but not a combination like aT.
• Return or Enter must be pressed to execute (enter) a command.
• Command statements are limited to 40 characters.
• Use the backspace or delete key to erase the last character.
Even though the initial AT code must be all upper or lower case, characters that follow can be any mix
of upper and lower case.
6.4.4 M
D
ONITOR
ISPLAY
As commands are typed they appear on the monitor so the operator can verify the input. This is called
local character echo. The echo may be turned on or off using AT commands. Refer to Local Character
Echo in the GENERAL COMMANDS section of this chapter for details.
6.4.5 C
-S
OMMAND
TATEMENT
The modem temporarily stores up to 40 characters in a buffer memory, so that you can repeat it with the
A/ command (see
Section 6.4.7
sends an ERROR message. To correct this condition, retype the command using 40 characters or less.
The AT characters and punctuation used in phone numbers do not take up space in the buffer. Also,
blank characters used as spaces to help increase readability are not counted. For example, the modem
reads the commands
ATD (212) 555-1212
ATD2125551212
ATD 212 555 1212
as having 11 characters each. Type the command in any of these forms.
Three things will clear the buffer: Turning the modem off, entering AT, or using the DTR reset feature.
Phone numbers stored using AT commands are limited to 34 characters.
6.4.6 B
K
ACKSPACE
EY
Use the backspace key to change the command statement or correct errors. The backspace key allows the
cursor to be moved back to the character(s) in error. The command can then be retyped from that point.
Example: ATD5551211 has been typed. To change the last 1 to 2, press the backspace key once, type 2,
and press Return to execute the command.
C
C
S
REATING
OMMAND
B
UFFER
). If this limit is exceeded, the modem does not accept the command and
CHAPTER 6: Asynchronous Operating Commands
TATEMENTS
NOTE
5 3
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