Siemens Mux_guide_v06 사용자 설명서

Multiplexer User's Guide 
Confidential / Released 

s

 

 

Mux_guide_v06 

Page 25 of 36 

30.06.2004 

 

The only approach to activate the multiplexer protocol is entering the appropriate AT 
command AT+CMUX=0. This enables the multiplexer control channel. The next step is to set 
up the multiplexer control channel as described in Chapter 4.3.2. 
 
 

The multiplexer control channel must be set up as the first channel followed by all other 
DLCIs. To do so, a SABM frame (see Chapter 4.2.3) must be sent to the GSM engine.  
 
The module responds either with a UA frame if the DLCI was set up, or with a DM frame if 
the DLCI was not set up. 
 
No provision is made for repeating the request if a response is not received. 
 
The state machine requesting the multiplexer control channel DLCI = 0 is the "initiating 
station", while the other is called the "responding station". 
 

SABM: P = 1
Address Field = DLCI of channel to be established

UA: F = 1, DLCI is being established
DM: F = 1, not ready, DLCI is not established
Address Field = DLCI of requested channel

 

Figure 7: DLC establishment 

 

A response is not essential for every command – for example, an unsolicited result code 
does not require a response. 
 

UIH:

P = 0, C/R = 1

UIH:

P = 0, C/R = 0

 

Figure 8: Information transfer