MC55 AT Command Set

4.8 AT+CMUX

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Refer to [5] which provides a detailed description of the multiplex architecture and step-by-step instructions 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.

Parameter Description

<mode>(num)

Multiplexer transparency mechanism

0

Basic option

<subset>(num)

Subparameters defined in GSM07.07 are adjusted for control and logical 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 logical 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 changed. All other parameters are not available.

4.8.1Restrictions on Multiplex mode

When the serial interface ASC0 is in multiplex mode, data and fax calls can only be set up on logical channel 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

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

 

 

 

MC55_ATC_V01.05

Page 100 of 469

2/10/04

Confidential / Released

 

 

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Siemens MC55 manual Restrictions on Multiplex mode, Subsetnum, +++