Specifications

TC35i AT Command Set
Confidential / Released
TC35i_ATC_V01.05 Page 114 of 278 04.08.2003
4.28 AT+CMUX Enter multiplex mode
Multiplex mode according to the ETSI TS 101 669 and GSM 07.10 enables one physical serial
asynchronous interface to be partitioned into three virtual channels. This allows you to take advan-
tage of up to 3 simultaneous sessions running on the serial interface. For example, you can send or
receive data or make a call on the first channel, while the other two channels are free to control the
module with AT commands.
The TC35i module incorporates an internal multiplexer and thus integrates all the functions needed
to implement full-featured multiplex solutions. For the application on top, customers have the flexibil-
ity to create their own multiplex programs conforming to the multiplexer protocol. To help system in-
tegrators save the time and expense of designing multiplexer applications, SIEMENS AG offers
WinMUX2k, a ready-to-use multiplex driver for Windows 2000 and Windows XP. Another approach
is to develop customized solutions based on the sources of the WinMux2k driver.
Refer to [4] which provides a detailed description of the multiplex architecture and step-by-step in-
structions of how to install and configure the multiplex mode. The WinMUX2k driver and its source
files can be supplied on request. Please contact your local distributor to obtain the latest installation
software and user's guide.
Test command
AT+CMUX=?
Response
+CMUX: (list of supported <mode>s) OK
Read command
AT+CMUX?
Response
+CMUX: <mode> OK
If error is related to ME functionality:
+CME ERROR: <err>
Write command
AT+CMUX=<mode>
Response
OK
If error is related to ME functionality:
+CME ERROR: <err>
Parameter
<mode> multiplexer transparency mechanism
0 basic option
Subparameters defined in GSM07.07 are adjusted for control and logical
channels as follows:
<subset> 0 UIH frames used only (control channel)
Reference
GSM 07.07
GSM07.10
Note
· 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 logical channels are established be-
fore 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 re-
turns to the AT command mode.
· The parameter maximum frame size (N1) of AT+CMUX in GSM07.10 is
fixed to 97 and cannot be changed. All other parameters are not avail-
able.