
USING THE BDLC PROTOCOL
UNILINK HOST
ADAPTER B–8
USER MANUAL
B.4 COMMANDS AND RESPONSESThe
following subset of the ANSI X3.66 standard is supported
by the UNILINK
Host
Adapter:
SNRM — The Set Normal Response Mode command is issued by the
host
computer to logically activate the adapter
’
s host interface and/or to
reset
the send and receive sequence counts. A SNRM must be sent to
the
adapter before any other command when the adapter is in the
“Disconnected
Mode”.
DISC — The Disconnect command is issued by the host computer to
logically
deactivate the adapter
’
s host interface and forces the adapter
to perform a hardware reset which executes the power
-up diagnostics.
When
the adapter receives the
DISC command, it will first respond with
a UA and then begin the reset. The adapter will not respond to any
commands
until it has completed the power
-up diagnostics.
NOTE
Power-up diagnostics requires a minimum of 7seconds to complete. During this time the adapterwill not respond to any host communications.UA — The Unnumbered Acknowledgment command is sent by the
adapter
in response to the SNRM
and DISC commands to acknowledge
their
reception.
DM — The Disconnect Mode response is returned by the adapter any
time
the host issues
a command other than an SNRM when the adapter
is
in the ”Disconnected Mode”.
RR
— The Receive Ready command is used by the host computer to poll
for
data and by the adapter to indicate the reception of a message and/or
that
the host can send another message.