Omron OMNUC W R88A-NCW152-DRT, Manual

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4.5 Connection and Wiring of the DeviceNet Communications Connector
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4
Terminating Resistors
Terminating resistors must be connected to both ends of the trunk line to reduce signal
reflection and stabilize communications. Terminating resistors can be connected either on a
T-branch Tap or as a Terminal Block.
When connecting terminating resistors as a Terminal Block, use special DeviceNet cable to
connect the Terminal Block.
Communications Power Supply
To enable DeviceNet communications, power for communications must be provided via the
special DeviceNet cables to the communications connector at each node. Use separate
power supplies for the communications, internal circuits, and I/O.
„ Connection Methods
The network connection methods are described in this section.
Trunk Line and Drop Lines
The trunk line is the cable with terminating resistors connected to both ends. A drop line is
a cable that branches from the trunk line. Special DeviceNet cables must be used for both
the trunk line and all drop lines.
Branching Patterns
• Branching Patterns from Trunk Line
• Branching Patterns from Drop Line
Various combinations of these connections can be used on the same network, as shown in
the following diagram.
1. One Drop Line from
2. Three Drop Lines (Maximum)
3. Node Connected Directly
Drop line
Drop line
Trunk
line
Trunk
line
Trunk
line
Trunk
line
Trunk
line
Trunk
line
T-branch
Tap
T-branch
Tap
Multi-drop
Node
Node
Node Node
Node
Trunk Line from Trunk Line
to Trunk Line
4. One Drop Line from 5. Three Drop Lines (Maximum)
from Drop Line
6. Node Connected Directly
to Drop Line
Drop
line
Drop
line
Drop
line
Drop line
Drop
line
Drop
line
Drop line
Drop
line
Multi-drop
T-branch
Tap T-branch
Tap
Node Node Node Node
Node
Drop Line