Siemens SIMATIC TIWAY 1 User Manual page 198

USING THE BDLC PROTOCOL
B.6 ILLUSTRATIVE BDLC SEQUENCES
Example B–1 illustrates an error-free BDLC sequence between the host
computer and the adapter. This sequence shows how information is efficiently
transferred, since acknowledgements are part of the control subfield and does
not require a separate transmission.
Example B–1 BDLC Error-free Sequence
Host Computer
(1) SNRM
(2) I–Frame, N(S)=0, N(R)=0, P
(3) I–Frame, N(S)=1, N(R)=0, P
(4) RR, N(R)=1, P
(5) RR, N(R)=1, P
(6) DISC
(7) RR, N(R)=0, P
UNILINK Host
RR, N(R)=1, F
I–Frame, N(S)=0, N(R)=2, F
RR, N(R)=2, F
I–Frame, N(S)=1, N(R)=2, F
... 7 second delay ...
B–13
Adapter
UA
UA
DM
UNILINK HOST ADAPTER
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