Texas Instruments 990 User Manual page 256
Dx10 hdlc communications package
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- Operation manual (276 pages) ,
- Manual (211 pages) ,
- Installation and operation manual (122 pages)
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Glossary
Network ID
A
four-digit
binary
coded
decimal value that ranges from
0000 to 9999.
Each station and
applications
program
that
uses the communications package is assigned a unique network
ID.
Network
IDs 0000 through 0099 are reserved for use by
the communications package.
The network ID becomes the
SID
when
data
is
sent from a location; the network ID becomes
the DID when data is addressed to a location.
NIT (Network Information Table)
The network' information table is
a
memory
resident
table
contained in the primary station and TX5 secondary stations.
There
is one long form NIT entry in the primary station for
each secondary station in the network and one short form NIT
entry for each
applications
program
in
the
the
primary
station
that
uses
the
communications
package.
Each TX
'secondary station contains one long form NIT entry
and
one
short
form
NIT
entry for each applications program in the
station that use the communications package.
Off-line
PVC
A condition pertaining to the status of
a
station
in
the
network.
When a station is taken off-line, it is logically
disconnected and all polls normally sent to the station
are
inhibited.
This
condition
may
be
caused, by an operator
action or by certain error conditions.
A
permanent
virtual
circuit
is
established
within
the
communications
package that provides the logical connection
between the primary station and each secondary station.
Packet Level (Level 3)
Level 3 provides the procedures that
control
the
flow
of
information
on
the
permanent virtual circuit (PVC).
Each
. message (called a data packet) includes a data packet header
and data packet sequence numbers.
The sequence numbers
are
used
to count data packets sent and received on the PVC and
to
limit
the
number
of
data
packets
that
can
be
unacknowledged
at
any given time.
Packets supported under
the DXlO HDLe Communications Package are standardized
under
the
CCITT
X.25
recommendations.
Packets without data are
also sent on the
PVC
to
indicate
the
receipt
of
other
packets
or
the
condition
of
the
sender
(i.e.,
busy,
resetting, not busy).
PDT (physical device table)
A table that contains the device-related
data
required
by
the DSR.
Physical Link Level (Levell)
Level
1
is
the
electronic interface between the stations
that are controlled on the FCCC board.
Glossary-4
2270526-9701
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