USING THE BDLC PROTOCOL
UNILINK HOST
ADAPTERB–7
USER MANUAL
The Unnumbered frame format is used to extend the number of supervisory
control functions. Frames transmitted using this format do not increment the
sequence counts at either the transmitting or receiving stations.
Commands/Responses
of this
type may or may not contain an Information field.
Valid
control field values are
hex
value
93
SNRM command
53
DISC command
73
UA response
1F
DM response
97
FRMR response
The
Poll/Final bit
should always be set to a binary one. This bit designates a poll
when
set by the host computer and designates the final frame when set by
the
adapter. BDLC operates with a window size of one, meaning that only one
outstanding command frame can be issued at any given time. Before the host
computer can send another command frame, it must receive a response frame
with
the Final bit set to one. The only exception to this is
if the adapter does not
respond
to the host computer
’
s poll within the 30 ms timeout.