Restrictions On Multiplex Mode; Table 4.1: Availability Of At Commands On Virtual Channels - Siemens Brodersen MC55 AT Command Manual

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
changed. 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 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 section 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
+++
AT+CBST
AT+CRLP
AT+CG... (GPRS commands)
AT+F... (Fax commands)
AT&S
ATA
ATD
ATDI
ATL
ATM
ATO
1)
ATS6
1)
ATS7
1)
ATS8
1)
ATS10
1)
ATS18
1) Siemens GSM engines support the registers S0 - S29. You can change S0,S3,S4,S5,S6,S7,S8,S10 and S18 using the
related ATSn commands (see starting from
2) The applicability of the
Protocol. Recommendations for implementing an appropriate modem status command (MSC) are provided in [5], Section
"Escape Sequence".
3) 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.
MC55_ATC_V04.00
Confidential / Released
Behavior on channel 1
not usable, but see note
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
). The other registers are read-only and for internal use only!
ATS0
escape sequence depends on the customer's external application based on the Mulitplexer
+++
Page 96 of 475
in GSM 07.10 is fixed to 98 bytes and cannot be
AT+CMUX
2)
Behavior on channel 2+3
not usable, but see note
not usable
not usable
3)
see note
not usable
not usable
no Data Calls
no Data Calls
not usable
not usable
not usable
not usable
not usable
not usable
not usable
not usable
not usable
2)
3/17/06