Sunsea AIoT SIMCom SIM800 Series, Application Note, Page: 24 / 25

SIM800 Series_Multiplexer_Application Note_V1.04
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6
TE sends FCon message
through DLC 0 to indicate
recovery of data transmission
——> F9 01 EF 05 A3 01 93 F9
4.5 Dealing with the Wrong Frame
After successful establishment of data channels, Data transmission between TE and MS is normal.
No Step
Data Direction
Hex Comment
TE<——>MS
1 TE sends hex value 0xF1 ——> F1 Note
2
TE tests AT command
transmission through DLC 1
after re-sync
——>
F9 07 EF 07 41 54 0D 06
F9
MS feeds back response and
synchronization has been reset
to normal
<——
F9 07 EF 07 41 54 0D 67
F9 F9 07 EF 0D 0D 0A 4F
4B 0D 0A 8A F9

Sending illegal hex byte will lead MS to receive a wrong frame.

When receiving illegal hex byte between frames, MS will just throw it away automatically and
waiting for the next frame. If next Frame is legal, the Multiplexer will handle it, and MS will give you
a right response; If not, the Multiplexer will still throw it away and wait for the next frame.
4.6 Closing down Multiplexers
No Step
Data Direction
Hex Comment
TE<——>MS
1
TE sends DISC frame to
request closing down DLC 1
——> F9 07 53 01 3f F9
MS feeds back UA frame to
accept
<—— F9 07 73 00 00 D7 F9
2
TE sends DISC frame to
request closing down DLC 2
——> F9 0B 53 01 B8 F9
MS feeds back UA frame to <—— F9 0B 73 01 92 F9
NOTE