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7.1 Introduction
This function is only available
with CD-i
players
equipped with
serial ports, port
#l
and port
#2.
When the CD-i players
are
connected
to each
other by using these
serial
ports then a
network is available. The main feature
of
this network is to
broadcast a message from a
"master"
CD-i player to
all
"slave"
CD-i player(s). However
sending a
message to
one
specific
player
is
not
possible.
7 .2 Definitions
Master player: A CD-i player in
a
network
which can
perform
a
copy to all the CD-i players in that
specific
network. There is only
one
player in
a
net-
work
that can be master. This specific master
station can not be changed until all the CD-i
players are turned
off.
The
CD-i
player that per-
forms the first external
copy will
be that master
player
and stays
the master
player
until
all
CD-i
players are turned
off.
Slave player: A CD-i player
in
a network
which cannot
perform
a copy
to the network. Only files
can
be
received from
a
network.
All
the
players
in the
CD-i
network
are slave
players
except
the
player
that performs
copy actions
to the network
(the
master player).
CD-i network: A network
of CD-i
players
connected
to
OSI-model:
each other
by using
a specific connector.
There is
one
master player that performs
a copy of
files to
all
the
slave
players.
OSI-model
stands
for
Open Systems
Intercon-
nection reference model. This model is
a step
into the direction
of
the international
standardi-
sation of different protocols.
7.3 Preconditions
When using the CD-i network
facility
,
the
following
precon-
ditions must be taken into
account:
• When connecting two players to
each other, a
physical
link
must be made between port
#l
of a player and
port
#2
of an
other player.
• The last player of the network may not be connected to the
first player
of the network. In
other words: you cannot
create
a ring network.
• It is not allowed to disconnect
a cable when
using the
network.
• Different CD-i networks may not
be connected.
In this
situation the
identification
of the players is not unique and
there
is a possibility that there
is
more than
one
master.
• The player that does the first
external copy will
be master
and
stays
master
until
all players are turned
off.
• A maximum of 25 CD-i players are recommended.
• Maximum
lenght
of the serial
connection
cable is
recommended
to be
10m.
(33ft).
When these preconditions are not fullfilled,
correct
behaviour
of the CD-i network cannot be guaranteed.
7. GROUPWORKING
7.4 Network configuration
For the
network,
all
the CD-i players must be connected
through serial
ports. This must be done by connecting port
#2
of a player with port
#l
of
another
player.
In figure
1
a network configuration
of
7
players is shown.
begin of
network
~l-----~ ►~----
...
1
~
1
Iayer E
~
1
Iayer
~
~
end of
~~------<►--~
network
FIGURE 1. CD-i network of
7
players
It
is very important
to
check
that these connections are done
correctly because
the
CD-i
player does not verify the hardware
links
.
For network control and also
for storage purpose, each player
has
a
unique identification
number in
a
network. This number is
not stored
in
NVRAM. The
identification number will be
automatically
assigned when
the network is used for the first
time after power on. The assigned
number is not visible for the
user.
When configuring
the network, the preconditions for the
network must be
fullfilled.
A
CD-i player within the created
network
is
able to copy a
file to
an external
(remote)
player.
This player will become
master and stays master until the
system
is
turned
off.
Configuring the network will
pass the following phases:
• Clearing
the
configurations
of
all
the CD-i stations in
the network.
• Assigning identification
numbers.
• Broadcast
network
status
to all the CD-i stations.
7.5 CD-i network protocol
The network protocol conforms
to the OSI-model standard. Not
all the OSI-layers are
used within the playershell network
program.
7.6 Layer I: physical link layer
The physical
layer
concentrates
on the communication channel.
In our case we need a
specific serial connection cable.
The connection
must have the following layout:
1. DCD
1. DCD
2. RXD
]t== = ~
~:=--....;;;§§~====12.
RXD
3.
TXD
3.
TXD
4.
DTR
4.
DTR
5. GND
5.
GND
6.
DSR
6.
DSR
7.
RTS
7. RTS
8. CTS
8.
CTS
9. RI
9. RI
FIGURE 2. CD-i
player
network
connection cable layout
19
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