Technical data

B1 B2 B1 B2L E
11 8 11111 8 111 1 111 8 111
DA DM DS DEEEL – – –
– – –
F
B1 B2 B1 B2D LFL LD LLFLD LLD LLD L
FN
O/M W12 W11 W1W2S S
D
B1B2
8 bits
8 bits 2 bits
100 Theoretical and general applications www.westermo.com
Frame format of the S-interface
The S-interface’s frames use 48 bits of which 36 are used for data transfer; the bit rate
in the S-interface is 192 kbit/s. The internal structure of the frames differs slightly
depending on in which direction the frames where sent. The figure below gives a
picture of how the different bits are used.
Frame structure
U-Frame when 2B1 Q coding
240 bits, 1.5 ms
12 words, 216 bits
48 bits 250 µs
NT to TE
TE to NT
S = Syncronisation pattern 18 bits
O/M = Operation and Maintenance 6 bits
A = Activation bit
B1 = B1 channel
(2 x 8 bits / frame)
B2 = B2 channel
(2 x 8 bits / frame)
D = D channel
(4 x 1 bit / frame)
E = Echo of previous
D bit
F = Framing bit
L = DC balancing
S = S-channel
N = Inverted F from
NT to TE
M = Multiframing bit
B A C K