The Omron CJ1W-EIP21, also cataloged as the CJ1W-EIP21 EtherNet/IP Unit, operates as a dedicated Ethernet communication interface for cyclic and message-based data exchange between CJ-series controllers and EtherNet/IP devices. The unit is classified as a CJ-series CPU Bus Unit and supports 100BASE-TX communication at 100 Mbit/s over a star topology.

Technical Identifier Matrix

Hardware Specifications

EtherNet/IP Communication and CJ CPU Bus Architecture

The CJ1W-EIP21 operates as a CPU Bus Unit rather than as a conventional Basic I/O Unit. Its communication processing therefore interfaces with the CJ-series CPU through the CPU Bus architecture while providing EtherNet/IP network connectivity.

The 100BASE-TX interface provides a nominal transmission rate of 100 Mbit/s. The specified maximum cable distance between a hub and node is 100 m. Network installation should maintain the Ethernet physical-layer requirements for twisted-pair cabling, connector termination, and electromagnetic compatibility.

The unit can be mounted on either a CPU Rack or Expansion Rack. The allowable number of mounted EtherNet/IP Units depends on the host controller family, with different limits specified for NJ-series, CJ/NSJ-series, and CP1H systems.

Package Contents & Ordering Information

• 1x Omron CJ1W-EIP21 EtherNet/IP Unit
• 1x CJ-series CPU Bus Unit
• Network cable and external Ethernet connection hardware are not assumed unless specifically included with the supplied unit
• Mounting and rack hardware are installed as part of the applicable CJ-series rack configuration

Field Installation Guidelines

• Install the CJ1W-EIP21 only in a compatible CJ-series CPU Rack or Expansion Rack configuration.
• Verify the permitted CPU Bus Unit count for the specific controller before installation.
• Confirm that the PLC configuration recognizes the installed CPU Bus Unit.
• Use 100BASE-TX-compatible twisted-pair Ethernet cabling for the network connection.
• Keep the Ethernet cable route separated from high-current motor, inverter, contactor, and switching-power wiring where practical.
• Maintain the maximum specified 100 m distance between a hub and the connected node.
• Use a suitable Ethernet switch or hub for the required star network topology.
• Ensure RJ45 connectors are correctly terminated and mechanically secured.
• Do not route communication cables through areas with excessive electromagnetic interference without appropriate cable-management and shielding measures.
• Ground the PLC rack and associated equipment according to Omron installation requirements and the site's protective-grounding system.
• Verify the 5 VDC CPU Bus Unit power budget because the module can consume up to 410 mA.
• Do not assume hot-swapping capability unless explicitly permitted by the applicable CJ-series hardware documentation.
• Confirm network configuration and node parameters before placing the EtherNet/IP network into operation.

Frequently Asked Questions

• Q: What Ethernet speed does the CJ1W-EIP21 support?

  A: The CJ1W-EIP21 provides 100BASE-TX communication at 100 Mbit/s. Its physical Ethernet interface uses baseband transmission with CSMA/CD media access.

• Q: What is the maximum transmission distance?

  A: Omron specifies a maximum transmission distance of 100 m between the Ethernet hub and node. Actual installation must also comply with the selected cable and network equipment specifications.

• Q: Where can the CJ1W-EIP21 be mounted?

  A: The unit can be installed on either a CPU Rack or Expansion Rack. The permissible number of CPU Bus Units depends on the host controller system.

• Q: How much 5 VDC current does the unit consume?

  A: The specified maximum internal current consumption is 410 mA at 5 VDC. This corresponds to approximately 2.05 W for the CPU Bus Unit power calculation.

• Q: How many CJ1W-EIP21 units can be installed?

  A: The maximum is system-dependent: 4 units for an NJ-series system, 8 units for CJ/NSJ systems, and 2 units for a CP1H system, including Expansion Racks where applicable.

• Q: What network topology is specified?

  A: The specified transmission path is a star form. A suitable Ethernet hub or switch is therefore used to connect the CJ1W-EIP21 with other network nodes.

• Q: What are the physical dimensions of the CJ1W-EIP21?

  A: The specified dimensions are 3.1 cm x 6.5 cm x 9.0 cm. The supplied unit weight is approximately 0.094 kg, excluding external packaging.

• Q: Is the CJ1W-EIP21 a Basic I/O Unit?

  A: No. The CJ1W-EIP21 is classified as a CJ-series CPU Bus Unit. It communicates with the PLC CPU through the CPU Bus architecture rather than occupying Basic I/O allocation as a discrete I/O module.