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ISDN TA/V
15.2.1 AT E
SCAPE
R
ESPONSE
T
IMEOUT
D
EFINITION
S-Register S12 defines the time in 20-millisecond increments following the
third escape character that the ISDN TA/V will wait before issuing an
OK
response. If one or more characters are received within this period the
OK
response will be suppressed. Whether this timeout has expired or not, the
ISDN TA/V is forced into command mode and will respond to valid AT
commands. If the characters that follow the escape sequence do not
constitute a valid AT command, or contain an invalid-command option,
the ISDN TA/V will immediately revert to data-transfer mode.
Following a valid AT command the ISDN TA/V will remain on-line and in
command mode until the call fails, or the ISDN TA/V is commanded back
on-line using the
ATO
command.
S12=
n
is the command used to alter the
escape response timeout, where
n
is a value from 0 to 255.
The default setting of
S12=50
results in a required escape response timeout
of 1 second.
15.3 Effect of the BREAK Key on a Terminal’s Keyboard
Similar in application to the escape sequence characters, the
BREAK
key on
a terminal keyboard can be used to interrupt data flow. The effect on the data
held within the ISDN TA/V’s buffer, and the state of the ISDN TA/V varies
according to the setting of the
\K
command, where:
\K0
A destructive break occurs each time the
BREAK
key is pressed. A
break character is immediately sent and the ISDN TA/V reverts to command
mode. All data in the ISDN TA/V’s buffers is lost.
\K1
A break character will be sent with all data in the ISDN TA/V’s
buffers being discarded. The ISDN TA/V however remains in data
mode.
\K2
An expedited break occurs each time the
BREAK
key is pressed. A
break is immediately sent and the ISDN TA/V reverts to command
mode. All data in the ISDN TA/V’s buffers is held there until the
ISDN TA/V reverts to data mode, at which time the buffered data
is transmitted down the line.
\K3
A break character is sent, the ISDN TA/V remains in data mode
and sends the data within its buffers.
\K4
A non-expedited break occurs each time the
BREAK
key is pressed.
The data within the ISDN TA/V’s buffers is sent to the remote
ISDN TA/V before the break character is sent. The ISDN TA/V
will then revert to command mode.
\K5
The data within the ISDN TA/V’s buffers is sent to the remote
ISDN TA/V, followed by the break character, although the ISDN
TA/V remains in data mode.
