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Omron CJ1W-ETN21 — dark grey slim CPU-bus module installed on a CJ backplane, viewed from below showing the backplane connector and right-side terminal block

Omron CJ1W-ETN21 — CJ Ethernet Unit, FINS, 10/100

SKU: CJ1W-ETN21

USD 265.00

CJ-series CPU-bus Ethernet unit. 10/100 Base-TX, FINS/TCP, FINS/UDP, FTP, socket service, mail. 200 mA at 5 VDC.

1-Year Warranty Full manufacturer warranty
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Product Overview

The Omron CJ1W-ETN21 is the CJ-series CPU-bus Ethernet unit. Pick it when a CJ or CJ2 cabinet needs network access for HMI upload, SCADA polling, or peer-to-peer FINS messages — without the EtherNet/IP tag-data-link layer.

It carries one 10/100 Base-TX RJ45 port on the front face and sits in any CJ-series CPU or expansion slot. The unit talks FINS over TCP and UDP, exposes an FTP server for project file transfer, opens TCP/UDP sockets for non-Omron devices, and can send or receive mail when an SMTP server is reachable. SNTP client support keeps the CJ clock in step with a network time server.

Power comes from the CJ backplane at 200 mA on 5 VDC; the body is the slim 31 x 90 x 65 mm form factor shared with the other CJ1W high-function units. Front-face LEDs cover RUN / ERC / SD / RD / LNK / 100M / ERH / TCP / FTP / HOST, so a quick glance tells you the link state and which service is in use.

The IP address can be set manually by the rotary NODE switches or assigned via DHCP. Up to four ETN21 units fit in a CJ rack (CPU plus expansion), and a built-in web page exposes basic diagnostics from any browser.

Compared with the CJ1W-EIP21, the ETN21 has no EtherNet/IP tag data links and no CIP message server. That makes it the right pick for legacy Omron cabinets that only need FINS and FTP — and the wrong pick when the SCADA expects tag data from a Rockwell scanner. CX-Programmer connects to it over Ethernet using FINS/TCP at the standard port 9600.

Key Features

  • CJ-series CPU-bus Ethernet unit, FINS-only (no EtherNet/IP tag data links, no CIP messaging)
  • One 10/100 Base-TX auto-negotiating RJ45 port on the front face, 100 m Cat 5e max
  • FINS/TCP and FINS/UDP for Omron PLC-to-PLC messaging and CX-Programmer upload
  • TCP/UDP Socket service for non-Omron TCP/UDP devices
  • FTP server for project file pull / push
  • SMTP mail send and POP3 mail receive triggered by PLC bits
  • SNTP client keeps the CJ clock in step with a network time server
  • Built-in web page exposes basic status and diagnostic info
  • IP address manual (rotary NODE switch) or DHCP
  • Front-face LED bank: RUN, ERC, SD, RD, LNK, 100M, ERH, TCP, FTP, HOST
  • 200 mA on 5 VDC from the CJ backplane
  • 31 x 90 x 65 mm slim body, same as CJ1W-ID262 / CJ1W-OD261
  • Up to 4 ETN21 units per CJ / CJ2 CPU rack
  • SKU: CJ1W-ETN21
  • Series: CJ-series CPU-bus Ethernet Unit

Best-Fit Applications

  • PLC-to-PLC FINS messaging between CJ and CS racks over the plant LAN
  • CX-Programmer remote program upload and online monitoring over Ethernet
  • Non-Omron TCP/UDP device polled from a CJ scan via the socket service
  • FTP push of recipe files or trend logs from the panel to a plant server
  • Mail alert when a PLC flag, alarm, or threshold trips in the field
  • Time sync on a CJ rack that has no battery clock of its own

Buying Checklist

  • Pick the CJ1W-ETN21 for FINS / FTP / socket / mail Ethernet on a CJ or CJ2 rack.
  • Pick the CJ1W-EIP21 instead when you also need EtherNet/IP tag data links to Allen-Bradley or third-party scanners.
  • Pick the CJ2H-CPU64-EIP CPU when the EtherNet/IP port belongs on the CPU itself rather than taking a slot.
  • Pick the CS1W-EIP21S instead for secure-comm features on a CS-series CPU bus.
  • Pick the CS1W-ETN21 when the rack is CS-series (the ETN21E name on the same form factor slot).
  • Confirm spare slots — the ETN21 takes a full CJ CPU-bus slot and counts toward the 4-units-per-rack maximum.

Technical Specifications

Series CJ-series CPU-bus Ethernet Unit
Model CJ1W-ETN21
Ethernet Port 1 x 10/100 Base-TX, auto-negotiate, RJ45
Protocols FINS/TCP, FINS/UDP, FTP server, TCP/UDP socket, SMTP, POP3, SNTP client
Web Server Built-in diagnostics page
Connections Up to 8 socket connections
IP Address Manual via NODE rotary switches, or DHCP
Current Draw 200 mA at 5 VDC from CJ backplane
Dimensions 31 x 90 x 65 mm (slim)
Mounting CJ-series CPU or expansion rack slot
Operating Temperature 0 to +55 °C
Approvals CE / KC / RoHS / UC1

FAQ for CJ1W-ETN21

What is the difference between CJ1W-ETN21 and CJ1W-EIP21?
The ETN21 is a FINS-only Ethernet unit — it speaks FINS/TCP, FINS/UDP, FTP, sockets, mail, and SNTP, but it does not run EtherNet/IP tag data links or CIP explicit messaging. The EIP21 adds the EtherNet/IP layer on top of the same 10/100 port. Pick the ETN21 when the rest of the plant is Omron FINS; pick the EIP21 when you also need to talk EtherNet/IP.
Can the CJ1W-ETN21 act as a Modbus-TCP master?
Not directly. The ETN21 has FINS and socket service. To read Modbus-TCP slaves from a CJ, route the request through a CJ1W-SCU serial gateway (CJ1 / CJ2 mode) or through an NJ EtherNet/IP master and Modbus-TCP slave routing (via CJ1W-IC101 + Modbus-RTU gateway) — the ETN21 itself only speaks the listed protocols.
How many CJ1W-ETN21 units fit on a CJ rack?
Up to four per CJ / CJ2 CPU rack, including expansion racks. That cap is set by the CJ CPU-bus specification, not by the ETN21 itself.
Does the ETN21 need an external 24 VDC supply?
No. The unit runs entirely from the 5 VDC supplied by the CJ backplane at 200 mA. There is no field-power terminal on the front face.

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