Omron CJ1W-EIP21 — CJ EtherNet/IP Unit, 256 Connections
SKU: CJ1W-EIP21USD 270.00
CJ-series CPU-bus EtherNet/IP unit, one 10/100 port, 180k CH tag data links, FINS / socket service, 256 connections, 5 VDC / 250 mA.
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Product Overview
The Omron CJ1W-EIP21 is the CJ-series CPU-bus EtherNet/IP unit. It sits in one CPU-bus slot on a CJ1 / CJ2 rack, draws 250 mA from the 5 VDC backplane, and exposes a single 10/100 Base-TX Ethernet port on the front face. Pick the EIP21 to add EtherNet/IP tag data links to an existing CJ build that needs to share up to 180,000 CH of real-time data with other EtherNet/IP devices -- Omron NX / NJ, Allen-Bradley ControlLogix, Keyence vision systems, or any ODVA-conformant controller on the same plant network.
Tag data links in plain language
Tag data links are deterministic, cyclic data exchanges between controllers -- the CJ1 / CJ2 PLC receives and sends fixed chunks of data on a set cycle (typically 1 to 100 ms) without any ladder-logic programming. The EIP21 supports up to 256 connections per unit, up to 256 nodes on the network, up to 722 CH per connection, and a total tag data link capacity above 180,000 CH. The producer / consumer model means the CJ1 / CJ2 PLC publishes data once and many devices consume it -- a typical 10-station conveyor with a CJ2 + 10 inverters at 50 words per inverter sits well within the 256 / 256 / 722 envelope.
CIP message + FINS + socket on one port
The same Ethernet port runs CIP explicit messaging for non-cyclic read / write between devices, plus FINS / UDP, FINS / TCP and Socket service for legacy CJ1 / NJ communications and for non-Omron TCP / UDP devices. A typical build uses CIP tag data links for cyclic I/O with a third-party EtherNet/IP scanner, FINS / TCP for programming-port upload from CX-Programmer, and Socket service for a third-party barcode reader.
EIP21 vs EIP21S
The bare CJ1W-EIP21 was discontinued by Omron in March 2025 in favor of the CJ1W-EIP21S that adds secure-communication features (secure-comm, user authentication, port on / off, IP packet filter) and official support for NJ-series CPUs. The EIP21 remains in stock at distributors for like-for-like spare replacement on existing CJ CPU-bus slots. Pick the EIP21S for new builds or for any install that needs network-security controls.
Key Features
- CJ-series CPU-bus EtherNet/IP unit, one slot wide on the CJ backplane
- One 10/100 Base-TX Ethernet port (RJ45, Auto-MDIX), 100 m cable run
- Tag data links: up to 256 connections per unit, up to 256 nodes on the network
- Up to 722 words per connection, total tag data link capacity above 180,000 CH
- Producer / consumer model -- no programming required for shared data
- CIP explicit messaging on the same port for non-cyclic read / write
- FINS / UDP + FINS / TCP + Socket service for legacy and third-party TCP / UDP devices
- Web server for diagnostics and tag-data-link configuration
- IP address: manual or DHCP, subnet mask, default gateway
- 5 VDC 250 mA from the CJ backplane -- no external supply
- UC1 / N / L / CE approvals; MADE IN JAPAN
- Discontinued March 2025 by Omron -- the CJ1W-EIP21S is the secure-comm successor
- Distinguishing feature vs CJ1W-ETN21: EIP21 adds EtherNet/IP tag data links; ETN21 is FINS / socket only
- SKU: CJ1W-EIP21
- Series: CJ-series CPU Bus EtherNet/IP Unit
Best-Fit Applications
- Add EtherNet/IP tag data links to an existing CJ1 / CJ2 rack for cyclic I/O with another ODVA scanner (e.g. Allen-Bradley ControlLogix, Keyence vision system)
- Cyclic tag-data-link exchange between CJ1 / CJ2 CPUs and a CJ2H-CPU6[]-EIP built-in EtherNet/IP scanner at up to 50 ms cycle
- FINS / TCP + Socket service on the same Ethernet port for CX-Programmer upload and a third-party TCP barcode reader
- Spare / replacement part for an existing CJ CPU-bus slot that already runs an EIP21 (the EIP21S is the official successor but the bare EIP21 stocks for like-for-like)
- Pick the CJ1W-EIP21S for new builds, secure-comm installs, or NJ-series CPU support -- the bare EIP21 is restricted to the CJ1 / CJ2 family
Buying Checklist
- Pick CJ1W-EIP21 to add EtherNet/IP tag data links to a CJ1 / CJ2 rack with 256 connections / 180,000 CH capacity.
- Pick CJ1W-EIP21S for new builds or installs that need secure-comm, user auth, or NJ-series CPU support (the EIP21 was discontinued March 2025).
- Pick CJ1W-ETN21 instead if only FINS / socket service is needed -- the ETN21 is cheaper and supports the same Ethernet port quartet minus EtherNet/IP.
- Pick CS1W-EIP21 for CS-series CPU-bus instead (the EIP21 only fits CJ1 / CJ2 / NJ CPU bus slots).
- Plan a free CJ CPU-bus slot on the rack and confirm the CJ1W-PA205R / PD025 PSU can carry the extra 250 mA 5 VDC draw.
- Use Network Configurator (CX-One) to set the tag data link connections on the EIP21 -- each connection consumes CH budget on a 256 / 256 / 722 envelope.
Technical Specifications
| Series | CJ-series CPU Bus EtherNet/IP Unit |
|---|---|
| Model | CJ1W-EIP21 (one Ethernet port, standard tag data links) |
| Ethernet Port | 1 x 10/100 Base-TX RJ45, Auto-MDIX, 100 m cable run |
| Tag Data Link Connections | Up to 256 per unit, up to 256 nodes total |
| Tag Data Link Capacity | Up to 722 CH per connection, 180,000 CH total or more |
| Message Service | CIP explicit messaging, FINS/UDP, FINS/TCP, Socket service (TCP / UDP) |
| Network Settings | IP address (manual or DHCP), subnet mask, default gateway; built-in web server |
| Power | 250 mA from 5 VDC CJ backplane (no external supply) |
| Mounting | One CJ CPU-bus unit slot, DIN-rail |
| Configuration Tool | CX-Programmer / CX-One / Network Configurator for EtherNet/IP |
| Discontinued Status | Discontinued March 2025 -- pick CJ1W-EIP21S for new builds, EIP21 for like-for-like spare replacement |
| Approvals / Origin | UC1 / N / L / CE; MADE IN JAPAN |
Resources & Downloads
FAQ for CJ1W-EIP21
What is the difference between CJ1W-EIP21 and CJ1W-ETN21?
Both are CJ-series CPU-bus Ethernet units with a single 10/100 Base-TX RJ45 port, but the EIP21 adds EtherNet/IP support. The EIP21 runs EtherNet/IP tag data links (cyclic producer / consumer between devices), CIP explicit messaging, FINS / UDP, FINS / TCP and Socket service. The ETN21 runs only FINS / UDP, FINS / TCP and Socket service -- no EtherNet/IP. Pick the EIP21 when the cabinet needs to talk to a third-party EtherNet/IP scanner / actuator or needs shared real-time data between Omron and non-Omron controllers. Pick the ETN21 when the only need is FINS / socket traffic to other Omron PLCs or a TCP / UDP device.
How many tag data link connections can the CJ1W-EIP21 handle?
Up to 256 connections per EIP21 unit, up to 256 nodes on the same EtherNet/IP network, up to 722 CH per connection. Total tag-data-link capacity exceeds 180,000 CH. This is the same envelope as the CJ2H-CPU6[]-EIP CPU built-in EtherNet/IP port, so swapping between a CPU-built-in port and an EIP21 unit does not change the data-link budget. A typical 10-inverter conveyor at 50 words per inverter uses only 50 connections / 50 nodes / 500 CH of the envelope.
Is the CJ1W-EIP21 still available?
Yes for like-for-like spare replacement on an existing CJ CPU-bus slot -- the bare CJ1W-EIP21 was discontinued by Omron in March 2025 in favor of the CJ1W-EIP21S that adds secure-communication features and NJ-series CPU support. Distributor stock of the bare EIP21 remains for retrofit and like-for-like use. For new builds, secure-comm installs, or NJ-series panels, pick the EIP21S instead.
Does the CJ1W-EIP21 work on a CJ2H-CPU6[]-EIP system?
Yes -- the EIP21 fits any CJ-series CPU-bus slot (CJ1H, CJ1M, CJ2H, CJ2M) on a CJ CPU rack. The CJ1W-IC101 I/O control unit is required on the CPU rack, and the CJ1W-II101 I/O interface unit is required on each expansion rack. For CJ1 / CJ2 CPUs without EtherNet/IP built in, the EIP21 is the standard add-on. The CJ1W-CIF11 RS-232C to RS-422A converter pigtail is not used here -- the Ethernet port on the EIP21 is the only network interface on the unit.
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