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COMSPHERE 3900 Series Modems
5-2 November 1996 3910-A2-GN32-30
Escape Sequence and Escape Guard Time
The
escape sequence is only issued when the modem is online and in Data mode. The 391x Series
modem uses three consecutive plus ( + ) characters as the escape sequence. (To change this value,
refer to S-Register S2 discussed later in Table 5-3 in the S-Register Format section.)
T
o prevent the modem from interpreting an embedded + + + in data as an escape sequence, the
Escape Guard T
ime value determines the length of the pause before and after the escape sequence
is issued. The 391x Series modem uses a one-second pause as the Escape Guard T
ime. (T
o change
this value, refer to S-Register S12 discussed later in Table 5-3 in the S-Register Format section.)
To enter online Command mode while in Data mode, enter the following sequence:
TYPE:
+ + +
Use the O command to return to Data mode from online Command mode. Enter the following
command:
TYPE: AT O
PRESS: Enter
Command Guidelines
Review the following guidelines before using any A
T Commands.
•
The escape sequence ( + + + ) is used to enter online Command mode from Data mode.
• The asynchronous character format for the AT command set must be one of the following:
—
8 data bits + no parity + 1 stop bit.
—
7 data bits + no parity + 2 stop bits.
— 7 data bits + parity + 1 stop bit (parity can be odd, even, mark, or space).
•
All commands (except A/ and + + + ) must begin with the characters A
T and end by
pressing the Enter key. The AT (or at) prefix clears the command buffer and matches the
modem speed and parity to that of the DTE. Commands can be upper- or lowercase, but the
modem will not recognize mixed case prefixes (At or aT).
•
Commands can be entered one at a time or in strings. Strings can have up to 40 characters
after the AT prefix. Y
ou can use spaces, hyphens ( - ), and parentheses ( ) as fillers to make
the commands easier to read; the modem ignores these fillers and they are not counted
among the characters which make up the command string. Commands must be entered on
one line and end with the carriage return character (Enter key).
•
Commands with the suf
fix n
have several options associated with them. For example, in the
Ln command, L1 sets the speaker volume to Low and L3 sets the speaker volume to High. If
no value is entered for the n suffix, the modem assumes a zero ( 0 ) value.
• The A/ command (without pressing the Enter key) causes the modem to repeat the last
command entered.
• Valid commands are acknowledged with numeric or word result codes (unless the result
codes have been disabled using the Q1 command). T
able 5-1 lists all available result codes
with numeric and word equivalents.