Siemens 7XV5662-0AD00/DD Handbuch Seite 54

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E1/T1 Frame structure
The time slots for the E1 frame are counted from 0 to 31 and for the T1 frame from 1 to 24.
The multiframe structure is used in the E1 mode. This structure is composed of 16 single
frames. The time slots 0 and 16 are not used for the transmission of user data. The structure
of the time slots 0 and 16 corresponds to the specifications of the standard G.732/G.704.
Time slot 0 is used for synchronisation and alarm transport. Time slot 16 is reserved for
signalling.
At the receiver side the CC-2M recognises frames with and without CRC-4. Provided that it
exists, the CRC is evaluated by the CC-2M and will be inserted as E-Bits into transmit frame.
At the receiver side the E-bits are not evaluated. There will be no external signalling over the
condition of the CRC.
The following table shows the assignment of the time slot 0. The first bit is used for CRC in
the case of even frames and for the identification of a multiframe and the E-bits in the case
of uneven frames. The second bit indicates whether it is an even or uneven frame (1 =
uneven, 0 = even). Bits 3 to 8 of any even frame are reserved for synchronisation (011011).
The S-bits are not used and have been set to "0". The A-bit indicates an error such as LOF
(Loss of Frame), LOS (Loss of Signal) and AIS (Alarm Indication Signal). When there is an
alarm, the A-bit is set to "1", otherwise to "0".
Sub- Frame
Multi- No.
frame
1
2
S = Spare Bit
A = Alarm Bit (Remote Alarm indication)
C = CRC Bit
E = CRC-4 Error indication bits
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1 2
0 C1 0
1 0 1
2 C2 0
3 0 1
4 C3 0
5 1 1
6 C4 0
7 0 1
8 C1 0
9 1 1
10 C2 0
11 1 1
12 C3 0
13 E 1
14 C4 0
15 E 1
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7XV5662-0AD00/DD, 7XV5662-0AD01/DD
Bit No.
3 4 5
0 1 1
A S S
0 1 1
A S S
0 1 1
A S S
0 1 1
A S S
0 1 1
A S S
0 1 1
A S S
0 1 1
A S S
0 1 1
A S S
6 7 8
0 1 1
S S S
0 1 1
S S S
0 1 1
S S S
0 1 1
S S S
0 1 1
S S S
0 1 1
S S S
0 1 1
S S S
0 1 1
S S S
C53000-B1174-C205-2