Omron CJ Series Operation Manual page 43

Communications Cables
CompoNet Networks use Round Cable I, Round Cable II, Flat Cable I (DCA4-4F10 Standard Flat
Cable), and Flat Cable II (DCA5-4F10 Sheathed Flat Cable) for Communications Cables.
Master Unit
The Master Unit manages the CompoNet Network and transfers I/O data between the CPU Unit and
the Slave Units.
There is only one Master Unit per network. The Master Unit must be connected to the end of the
trunk line.
Slave Units
Some Slave Units receive output data from the Master Unit across the CompoNet Network and out-
put it. Other Slave Units send data that has been input across the network to the Master Unit. There
are two types of Slave Unit according to the I/O capacity of the Slave Unit.
• Word Slave Units: A Word Slave Unit is allocated 16 bits (i.e., 16 I/O points) in the I/O memory of
the CPU Unit.
• Bit Slave Units: A Bit Slave Unit is allocated 2 bits (i.e., 2 I/O points) in the I/O memory of the CPU
Unit.
Repeater Unit
Using Repeater Units enables expanding network connections as follows:
• Extending the Communications Cable
• Increasing the number of nodes (Units)
• Creating long-distance T-branches from the trunk line and sub-trunk lines (See note.)
• Converting between different types of cable (Round Cable I, Round Cable II, Flat Cable I, and Flat
Cable II)
A sub-trunk line downstream from a Repeater Unit can be connected with the same communications
specifications (i.e., distances and number of Slave Units) as the trunk line.
Up to 64 Repeater Units can be connected per network (i.e., per Master Unit). When Repeater Units
are connected in series from the Master Unit, up to two layers can be created.
Note The physical layer is not connected across a Repeater Unit. The connection is thus different
from a branch connection, which branches the same physical layer.
Terminating Resistors
With a CompoNet Network, the Master Unit is located at one end of the trunk line and a Terminating
Resistor is connected to the other end of the trunk line.
If Repeater Units are used, each Repeater Unit is treated like a Master Unit, i.e., Terminating Resis-
tor is connected to the most remote end of the sub-trunk line downstream from the Repeater Unit.
Note A Terminating Resistor reduces signal bouncing to stabilize communications and must
always be connected to the most remote end of the network lines below the Master Unit and
each Repeater Unit. Always connect a Terminating Resistor to ensure the quality of the trans-
mission path.
Trunk Lines and Branch Lines
The trunk lines and branch lines in a CompoNet Network are defined as follows:
• Trunk line: The transmission path between the Master Unit and the Terminating Resistor.
• Sub-trunk line: The transmission path between the Repeater Unit and the Terminating Resistor
(when a Repeater Unit is used).
• Branch line: The transmission path created using a T-branch from the trunk line or sub-trunk line.
CJ-series CompoNet Master Unit Operation Manual for NJ-series CPU Unit (Cat. No. W493)
1 Introduction
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