53
Chapter 11: Commanding the ISDN TA/V
11.4.4 E
DITING A
C
OMMAND
L
INE
If you make a mistake when compiling a long ISDN TA/V command line, the
backspace key or
<Ctrl>H
(default setting as held in S-register S5) can be used
to reposition the cursor and correct the mistake. The keyboard’s delete key
does not have the same effect.
11.4.5 R
EPEATING A
C
OMMAND
L
INE
One of only two exceptions to the prefix and terminator character
requirement rule is the command A
/
(A followed by a forwardslash). Issue
this command and the ISDN TA/V will repeat the last command line that it
executed.
11.5 Interrupting Data Traffic to Issue AT Commands
Providing that your ISDN TA/V is off-line (you have not issued a dial
command or answered an incoming call), and is therefore not in
communication with a remote ISDN TA/V, AT commands can be entered via
the
CONTROL
port any time, or via the DTE interface at any time that your
communications software is in terminal mode and the interface is configured
to accept asynchronous command.
If the ISDN TA/V is on-line (passing data between your computer and a
remote computer), the passage of data has to be interrupted if you wish to
issue any commands to your ISDN TA/V: for example if you wish to hang-up
the call. Note that this interrupting action does not break the connection to
the remote ISDN TA/V.
To interrupt the data flow, a special command is used which does not require
either the AT prefix or the terminator character.
At your keyboard type
+++
to interrupt the data flow, and put the ISDN TA/V
into command mode. Any characters subsequently sent to the ISDN TA/V are
seen as an AT command sequence. If a pause occurs between the third escape
character and the first subsequent character, that is longer than the time
period defined within S-Register S12 (see
Section 15.1.3
), the ISDN TA/V will
return the
OK
result code (
OK
will be displayed on-screen), confirming that
it is in command mode.
If no pause occurs between the third escape character and the first
subsequent character, or the pause is shorter than that defined in S12, the
ISDN TA/V will still respond to a valid AT command string in the normal
manner. However, if the characters received do not form a valid AT
command string, the ISDN TA/V will immediately revert to data-
transmission mode.
