MC55 AT Command Set
4.8 AT+CMUX s
m
obil
e
MC55_ATC_V01.05 Page 102 of 469 2/10/04
Confidential / Released
4.8.2 Second serial interface ASC1
The second serial interface ASC1 is intended as an auxiliary interface for applications which need multiple par-
allel access to the module (e.g. to query status information during a data call), but cannot use the GSM 07.1 0
multiplexing protocol. Therefore this interface offers limited functionali ty only.
• No DTR, DSR, DCD, RING signals. These hardware lines do not e xist. As a result, AT commands controlling
the behavior of these lines (AT&D, AT&C, AT&S) are not allowed and return ERROR.
• No Autobauding. The hardware is not capable of automatically detecting the baudrate on this interface, so
the AT command which selects autobauding (AT+IPR=0) is not allowed and ret urns ERROR.
• No CSD calls, so all related AT commands cannot be used and return ERROR.
• No fax calls, so all AT+F commands cannot be used and return E RROR.
• No GSM 07.10 Multiplexer. if issued on the second interface AT+CMUX=0 returns ERROR.
ASC1 is disabled when the multiplexer is enabled on the first serial interface ASC0. Yet, both ASC1 and the mu l-
tiplexer channel 2 are using the same parameters, and thus, the same user defined profile (if any). As a result,
a user profile stored on multiplexer channel 2 takes effect on ASC1 after closing the multiplexer and starting up
ASC1. Likewise, a user profile stored on ASC1 will be loaded on multiplexer c hannel 2.
This may be a problem when ASC1 is not connected, but flow control (for example AT\Q1 or AT\Q3) is stor ed to
the user profile on the multiplexer channel 2. In this case, flow control takes effect on ASC1, when the m ultiplexer
is switched off. If then for example a large amount of UR Cs is generated, their transmission might be stopped
due to the flow control. To avoid this problem we recommend that you do not activate f low control on multiplexer
channel 2 when you set up a user profile with AT&W.
AT+CFUN If the ME is in Multiplexer mode, it is not recommended to activate SLE EP mode
with AT+CFUN=<fun>. The best approach to properly control SLEEP mode in this
case is to issue the PSC messages described in [5], chapter "Power sa ving control
(PSC)".
AT+CPMS Parameter <mem3> will be the same on all instances, but the settings of <mem1>
and <mem2> may vary on each instance.
AT^SSDA If one instance is set to <da>=1 and <mt>=1, then all other instances must be con-
figured for <mt>=0.
Command Description