SARA-R4/N4 series - AT Commands Manual
UBX-17003787 - R09
10 V24 control and V25ter
Page 95 of 307
10.3.3 Defined values
Parameter
Type
Description
<value>
Number
•
0: the DCE ignores circuit 108/2
•
1 (default value and factory-programmed value): upon an ON-to-OFF transition of
circuit 108/2, the DCE enters online command state and issues an OK result code
•
2: upon an ON-to-OFF transition of circuit 108/2, the DCE performs an orderly
cleardown of the call. The automatic answer is disabled while circuit 108/2 remains
OFF
10.3.4 ~+++ behavior in PSD &D
SARA-R4 / SARA-N4
The ~+++ behavior in PSD &D is not supported.
• A special meaning of the &D value is provided for the ~+++ sequence during a PSD data transfer with PPP
L2 protocol (this is outside the V25-ter specification scope). The ~+++ causes context deactivation during
a PSD data transfer session for the AT&D0 and AT&D2 value (the +++ return to on-line command mode is
provided for each &D value during a CSD data call)
• A different implementation for the ~+++ is done with the &D1 value: the PSD data transfer is escaped and
system returns in the on-line command state. The
command is used to resume the PSD data transfer
session
• During the on-line command mode different AT commands can be sent but data calls in PSD on-line
command mode cannot be granted (activate the AT+CRC=1 mode to identify the kind of call and reject data
incoming calls if PSD is in the on-line command mode)
For more details see the ITU-T Recommendation V250
, ITU-T V.25ter Recommendation
ITU-T V.32 Recommendation
See the corresponding module system integration manual for the DTR behavior during the initialization
phase of the module.
10.3.5 Circuit 108/2, +++ behavior for the different &D: summarizing tables
CSD data mode
Event
DTE sends escape sequence (e.g. +++)
DTR On to Off transition
&D0
DCE enters command mode
No action
&D1
DCE enters command mode
Switch to command mode
&D2
DCE enters command mode
Cleardown call
Table 6: CSD data mode
PSD data mode (PPP L2 protocol case)
Event
DTE sends ~+++
DTR On to Off transition
&D0
Context deactivation
No action
&D1
DCE enters command mode
DCE enters command mode
&D2
Context deactivation
Context deactivation
Table 7: PSD data mode
10.3.6 Notes
• The ON/OFF DTR transition in direct link forces the DCE into command mode. In case of AT&D0 the DTR
transition is ignored, also in direct link.
• The escape sequence for the PSD data mode with a L2 protocol different from the PPP is not ~+++, and
it could be not supported. See the
#unique_383/unique_383_Connect_42_t1
for more information.
