Restricted Use Of At Commands In Multiplex Mode; Table 8: Availability Of At Commands On Virtual Channels - Siemens MC35 Command Set

AT Command Set

4.28.1 Restricted use of AT commands in Multiplex mode

In Multiplex mode, the operation of several AT commands varies from the normal mode. This chapter
summarizes the concerned commands. For general rules and restrictions to be considered in Multiplex
mode please refer to [5].
Data, fax and GPRS calls can only be set up on logical channel 1. Due to this restriction, AT com-
mands have a different behaviour on channels 2+3 compared to channel 1. Several commands are
not available, others return different responses. These commands are listed in the table below:

Table 8: Availability of AT commands on virtual channels

Command
+++
ATE
AT+CBST
AT+CR
AT+CRLP
AT+CG... (GPRS commands) as described
AT+F.... (Fax commands)
AT&C
AT&D
AT&F
AT&S
AT&V
ATA
ATD
ATDI<n>
ATO
1
ATS0 )
1
ATS3 )
1
ATS4 )
1
ATS5 )
1
ATS6 )
1
ATS7 )
MC35_ATC_01_V05.00
turns to the AT command mode.
3. There are various options to switch from data mode to command mode:
a) Escape sequence +++
b) Circuit 108/2 (DTR) changes from ON to OFF, reaction depends on
command at&d (caution if AT&D0: TA ignores status on DTR).
c) The message Modem Status Command (MSC) for control channel is
defined by the multiplexer protocol GSM07.10. MSC conveys V.24
signals. Bit 3 of Control Signal Octet is DTR, reaction depends on
command at&d (caution if AT&D0: TA ignores status on DTR).
4. The parameter maximum frame size (N1) of AT+CMUX in GSM07.07 is
fixed to 97 and cannot be changed. All other parameters are not avail-
able.
5. Multiplex mode can be terminated by AT^SMSO (,AT^SMSO Switch off
mobile station" pg. 202). It has to be reestablished after power-on.
Behaviour on channel 1
3)
as described
as described
as described
as described
as described
as described
as described
as described
as described
as described
as described
as described
as described
as described
as described
as described
as described
as described
as described
as described
as described
Page 102 of 256
Differences on channel 2+3
no data calls
as described
not usable
not usable
not usable
usage not recommended
not usable
not usable
not usable
data call parameters not changed,
S3, S4 not changed
not usable
data call parameters not displayed
no data calls
no data calls
not usable
not usable
not usable
as described
as described
not usable
not usable
not usable
2)
15.07.2002