Multiplexer User's Guide
Confidential / Released
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Mux_guide_v06 Page 26 of 36 30.06.2004
4.3.4 DLC release
No provision is made to repeat the request if no response is received.
DISC: P = 1
UA: F = 1
DM: F = 1 responding station is
already disconnected
Figure 9: DLC release
4.3.5 Close-down procedure
To close down the multiplexer follow these two steps:
• First, disconnect all DLCIs by sending the DLCI Release command within the multiplexer
control channel frame (as described in section 4.3.6).
• Finally, close down the multiplexer control channel (DLCI = 0) by sending the multiplexer
close down command CLD (see section 4.3.7). After this, both the “initiating station” and
the “responding station” revert to AT command mode.
Before closing the multiplexer make sure that there is no ongoing activity on one of the
channels. For example, check that voice, CSD or GPRS connections have ended and wait
until all pending AT command responses are received.
4.3.6 Multiplexer control channel
DLCI = 0
Type
1 Octet
Length
n Octets
Value 1
1 Octet
Value 2
1 Octet .....
Value n
1 Octet
Information Field
Figure 10: Multiplexer control channel
The commands are sent as information in the multiplexer control channel frame.
Type field:
Bit 1 Bit 2 Bit 3 Bit 4 Bit 5 Bit 6 Bit 7 Bit 8
EA C/R T1 T2 T3 T4 T5 T6
EA bit: Extension bit.
In the last octet of the sequence the EA bit = 1, otherwise = 0.
If there is only on octet, EA bit = 1 is set.
C/R bit: Indicates whether the sequence is a command or a response.
T-bits: Coding of the command type.