BGS2T AT Command Set
4.8 AT+CMUX
BGS2T_ATC_V01.301 Page 105 of 554 1/31/12
c
Parameter Description
Enable Multiplex mode.
0 Basic option
4.8.1 Restrictions on Multiplex mode
In Multiplex mode, CSD and fax calls can only be set up on logical channel 1. Due to this restriction, AT com-
mands have a different behavior on channels 2+3 compared to channel 1. Several commands are not available,
others return different responses. This section summarizes the concerned commands. For general rules and
restrictions to be considered in Multiplex mode please refer to "Multiplexer User's Guide" [3].
Table 4.1: Availability of AT Commands on Virtual Channels
1) The applicability of the
+++ escape sequence depends on the customer's external application based on the Mulitplexer
Protocol. Recommendations for implementing an appropriate modem status command (MSC) are provided in "Multiplexer
User's Guide" [3], Section "Escape Sequence".
2) PDP contexts can be defined on any channel, but are visible and usable only on the channel on which they are defined
(thus it is not possible to define a context on channel 2 and activate it on channel 3). GPRS connections can be estab-
lished on two channels at a time.
Table 4.2: Summary of AT commands with Different Behavior in Multiplex mode
<mode>
(num)
Command Behavior on channel 1 Behavior on channel 2+3
+++ not usable, but see note
1)
not usable, but see note
1)
AT+CBST as described not usable
AT+CRLP as described not usable
AT+CG... (GPRS commands) as described see note
2)
AT+F... (Fax commands) as described not usable
ATA as described no CSD/Fax calls
ATD as described no CSD/Fax calls
ATDI as described not usable
ATO as described not usable
ATS10 as described not usable
ATS18 as described not usable
Command Description
AT\Q It is recommended to use hardware flow control (AT\Q3). XON/XOFF flow control
(AT\Q1) is not supported in Multiplex mode.
See note regarding AT\Qn settings stored with AT&W if Multiplex mode is active.
AT&V Different default configurations on channels 1, 2 and 3.
AT&W Different user profiles can be stored on each channel.
AT+IPR Before starting Multiplex mode, ensure that the bit rate set with AT+IPR is not lower
than 57600 bps. For using data services in Multiplex mode it is recommended to
set at least 115200 bps.
In Multiplex mode, the write command AT+IPR=<rate> will not change the bit rate
currently used, but the new bit rate will be stored and becomes active, when the
module is restarted.
AT+IPR=0 Multiplex mode cannot be activated while Autobaud mode is enabled.
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