SIM800 Series_Multiplexer_Application Note_V1.04
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Contents
About Document ..................................................................................................................................3
Version History ......................................................................................................................................3
Scope ....................................................................................................................................................3
Contents................................................................................................................................................4
1Introduction ...................................................................................................................................6
1.1 Purpose of the document............................................................................................................6
1.2 Related documents.....................................................................................................................6
1.3 Conventions and abbreviations...................................................................................................6
2Multiplexer Introduction ...............................................................................................................8
2.1 Multiplexer Design Purpose........................................................................................................8
2.2 Architecture Diagram ..................................................................................................................8
2.3 Restrictions.................................................................................................................................9
3SIMCOM Multiplexer Protocol....................................................................................................10
3.1 Transmission Frame Structures................................................................................................10
3.1.1 Opening and Closing Flag Field.....................................................................................10
3.1.2 Address Flag Field .........................................................................................................10
3.1.3 Address Flag Field ......................................................................................................... 11
3.1.4 Length Field ................................................................................................................... 11
3.1.5 Information Field ............................................................................................................12
3.2 Frame Type...............................................................................................................................12
3.2.1 SABM.............................................................................................................................12
3.2.2 UA..................................................................................................................................12
3.2.3 DISC...............................................................................................................................13
3.2.4 DM..................................................................................................................................13
3.2.5 UIH.................................................................................................................................13
3.2.6 UI ...................................................................................................................................13
3.3 DLC Establishment...................................................................................................................13
3.4 Closing Down DLC....................................................................................................................14
3.5 Control Channel........................................................................................................................14
3.6.1 PSC................................................................................................................................15
3.6.2 CLD................................................................................................................................15
3.6.3 Test.................................................................................................................................15
3.6.4 MSC...............................................................................................................................16
3.6.5 FCoff ..............................................................................................................................16
3.6.6 FCon ..............................................................................................................................17
3.6.7 PN,NSC,RPN,RLS,SNC.................................................................................................17
