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2-2
2-1 Network Configuration Overview
The following diagram shows the configuration of a CompoBus/D Network.
CompoBus/D
cables are used.
T: T-branch connection
M: Multi-drop connection
CompoBus/D cables (5-wire cables) are
used for the trunk lines and drop lines.
Node
Drop line
Drop line
Drop line
T-branch
Tap
Drop line
Drop line
Trunk line Trunk line Trunk line
Trunk
line
Trunk line Trunk line
Node
Node
Node
Node
Node
Node
Node
Node
Node
TT TT
M
M
T
M
MM
T
Terminating Resistors
are connected at each
end of the trunk line.
Power Supply Tap
or T-branch Tap
24 VDC
Communications
power supply
CompoBus/D
cables are used.
T-branch
Tap
T-branch
Tap
T-branch
Tap
Drop line Drop line
T-branch
Tap
T-branch Tap
Terminating Resistors
are connected at each
end of the trunk line.
2-1-1 Network Components
H Nodes
There are two kinds of nodes on a CompoBus/D Network: The Master and Slaves. The Slaves connect
to external I/O and the Master administers the Network and manages the external I/O of the Slaves. The
Master and Slaves can be connected at any location in the Network, as shown in the preceding diagram.
H Trunk/Drop Lines
The trunk line refers to the cable that has Terminating Resistors on both ends. Cables branching from
the trunk line are known as drop lines. The trunk line length does not necessarily coincide with the maxi-
mum length of the Network. CompoBus/D communications are transmitted through 5-wire cables. The
cables come in thick and thin versions.
H Connection Methods
Two methods can be used to connect CompoBus/D nodes: The T-branch method and the multi-drop
method. With the T-branch method, the node is connected to a drop line created with a T-branch Tap.
With the multi-drop method, the node is directly connected to the trunk line or the drop line. Secondary
branches can be made from a drop line. Both of these connection methods can be used in the same
Network.
H Terminating Resistors
Terminating Resistors are connected at each end of the trunk line to reduce signal reflection and stabi-
lize communications. There are two kinds of Terminating Resistors available: One that is provided with
a T-branch Tap and a Terminal-block Terminating Resistor. Use a CompoBus/D Cable when connecting
a Terminal-block Terminating Resistor.
H Communications Power Supplies
To use CompoBus/D, connect a communications power supply to the communications connector of
each node with a 5-wire cable. Basically, a communications power supply, internal circuit power supply,
and I/O power supply must be provided separately.
CompoBus/D Communications Line Design Chapter 2