MC55 AT Command Set
4.8 AT+CMUX s
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MC55_ATC_V01.05 Page 100 of 469 2/10/04
Confidential / Released
Refer to [5] which provides a detailed description of the multiplex architecture a nd step-by-step instructions of
how to install and configure the multiplex mode. The WinMUX2k driver a nd its source files can be supplied on
request. Please contact your local distributor to obtain the latest installa tion software and user's guide.
Parameter Description
Multiplexer transparency mechanism
0 Basic option
Subparameters defined in GSM07.07 are adjusted for control and lo gical channels as follows
0 UIH frames used only (control channel)
Notes
• The write command is used to enter the multiplex mode. The setup of the logical channels is initiated by the
TE, i.e. the TE acts as initiator. This means that the TE shall ensure that logi cal channels are established
before any further actions on the channels can be started.
• There is a timeout of five seconds, if the multiplexer protocol is enabled and no multiplexer control channel is
established. The GSM engine returns to AT command mode.
• The parameter maximum frame size (N1) of AT+CMUX in GSM07.10 is fixed to 97 and cannot be cha nged.
All other parameters are not available.
4.8.1 Restrictions on Multiplex mode
When the serial interface ASC0 is in multiplex mode, data and fax calls can only be set up on logical chan nel 1.
Due to this restriction, AT commands have a different behavior on channels 2+3 compared to channel 1. Several
commands are not available, others return different responses. This chapter summarizes the concerned com-
mands. For general rules and restrictions to be considered in Multiplex mode please refer to [5].
Table 4.1: Availability of AT Commands on Virtual Channels
<mode>(num)
<subset>(num)
Command Behavior on channel 1 Behavior on channel 2+3
+++ not usable, but see note 2) not usable, but see note 2)
AT+CBST as described not usable
AT+CRLP as described not usable
AT+CG... (GPRS commands) as described see note 3)
AT+F... (Fax commands) as described not usable
AT&S as described not usable
ATA as described no Data Calls
ATD as described no Data Calls
ATDI as described not usable
ATL as described not usable
ATM as described not usable