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Open Network for High-Speed Control


CompoNet offers the ideal mix of high speed, ample capacity, and ease-of-use needed to let you build the best machine.

Network Specifications

CompoNet is made up of segments divided by repeater unit.

There are four CompoNet baud rates, from 4 Mbps ultra-fast mode to 93.75 kbps long-distance mode.
The wiring specifications depend on the baud rate. Select the one that best matches your application.

CompoNet Specifications 2

Baud rate Cable type Trunk line and
sub-trunk line
length (When
2 repeaters
are used.)
Number of
slaves per
number of
Total sub-
length per
4Mbps Round cable I, II
Flat cable I
30m (90m) 32 --- --- --- --- --- ---
3Mbps Round cable I, II
Flat cable I
30m (90m) 32 0.5m 8m 3/meter 1 --- ---
1.5Mbps Round
cable I
100m (300m) 32 --- --- --- --- --- ---
30m (90m) 32 2.5m 25m 3/meter 3 --- ---
Round cable II
Flat cable I
30m (90m) 32 2.5m 25m 3/meter 3 0.1m 2m
93.75kbps Round cable I 500m (1500m) 32 6m 120m 3/meter 1 --- ---
Round cable II
Flat cable I
200m (600m) 32 200 meter free wiring total wire length per segment

Relation between Baud Rate and Communications Cable

The Cable that can be used and the required baud rates are automatically determined by whether a trunk line-branch line formation or an unrestricted wiring formation is used.

Cable type Baud rate
4Mbps 3Mbps 1.5Mbps 93.75kbps
Round cable I Trunk line-branch line wiring
formation (See note 1.)
Trunk line-branch line
wiring formation
Trunk line-branch line
wiring formation
Trunk line-branch line wiring formation
Round cable II Unrestricted wiring formation
Flat cable I

Note: (1) If a baud rate of 4 Mbps is used, branching is not possible from the trunk line. (Only multidrop connections are possible.)

The following table shows the conditions and restrictions for each formation.

Item Wiring formation
Trunk line-branch line formation Unrestricted wiring formation
Master Unit location End of network Anywhere in network (not necessarily at the end)
Maximum number of Slave
Units connected to any one
branch line
1 or 3 depending on the cable type and baud rate No restrictions
Terminating Resistor location On the opposite ends of the trunk line and all sub-
trunk lines from the Master Unit and each Repeater Unit
On the most remote ends from the Master Unit
and each Repeater Unit

Example of wiring for 4Mbps (Application: Ultra-fast communications)

CompoNet Specifications 9

Example of wiring for 3Mbps (Application: Fast communications with branching)

CompoNet Specifications 10

Example of wiring for 1.5 Mbps (Application: Balance of fast communications and branching)

CompoNet Specifications 11

Example of wiring for 93.75 kbps (Application: Long-distance wiring and free wiring)

Example using round cable I

CompoNet Specifications 13

Free wiring when using flat cable I or round cable II

With this wiring formation, there is no distinction between the trunk line and branch lines. There are no wiring restrictions as long as the total cable length does not exceed 200 m. There is also no limit in the number of branches.

CompoNet Specifications 14

Communications Specifications

Item Specification
Communications protocol CompoNet Network protocol
Types of communications Remote I/O communications (programless, constant sharing of data with Slave Units) and message
communications (explicit message communications as required with Slave Units and FINS message
communications as required with controllers) *1
Baud rate 4 Mbps *2, 3 Mbps, 1.5 Mbps, 93.75 kbps
Modulation Base-band
Coding Manchester code
Error control Manchester code rules, CRC
Communications media *3 The following media can be used.
Round cable I 2-wire 0.75 mm2
Round cable II 4-wire 0.75 mm2
Flat Cable I
Communications distance and
Refer to Cable Types, Baud Rates, and Maximum Distances in the Master Unit Operation Manual.
Connectable Master Units CompoNet Master Units
Connectable Slave Units CompoNet Slave Units
Maximum I/O capacity Word Slave Units: 1,024 inputs and 1,024 outputs (2,048 I/O points total)
Bit Slave Units: 256 inputs and 256 outputs (512 I/O points total)
Maximum number of nodes Word Slave Units: 64 input nodes and 64 output nodes
Bit Slave Units: 128 input nodes and 128 output nodes
Repeater Units: 64 nodes
Bits allocated per node address Word Slave Units: 16 bits
Bit Slave Units: 2 bits
Maximum number of nodes per
trunk line or sub-trunk line
32 nodes (Slave Units and Repeater Units)
Applicable node addresses Word Slave Units: IN0 to IN63 and OUT0 to OUT63
Bit Slave Units: IN0 to IN127 and OUT0 to OUT127
Repeater Units: 0 to 63
Repeater Unit application
Up to 64 Repeater Units can be connected per network (i.e., per Master Unit). Up to 32 Repeater
Units can be connected per trunk line or per sub-trunk line. When Repeater Units are connected
in series from the Master Unit, up to two extra segment layers can be created (i.e., up to 2
Repeater Units are allowed between a Slave Unit and the Master Unit).
Signal lines Two lines: BDH (communications data high) and BDL (communications data low)
Power lines Two lines: BS+ and BS- (power for communications and internal Slave Unit circuits)
Power is supplied from the Master Unit or Repeater Units.
Communications power supply
24 VDC ±10%
Connection forms Standard or Sheathed Flat Cable at baud rate of 93.75 kbits/s: No restrictions
Other cables or baud rates: Trunk line and branch lines
Connections for Slave Units and Repeater Units: T-branch or multidrop connections

*1 FINS message communications are supported by CJ-series Controllers only.
*2 A baud rate of 4 Mbps is not supported for branch lines and thus cannot be used for Slave Units with Cables (i.e., Bit
      Slave Units).
*3 Round cable I, round cable II and Flat Cable I are all different types of cable. To use more than one type of cable at
      a time, Repeater Units must be used to separate them on trunk lines and sub-trunk lines.