Part of the Omron CJ-Series PLCs series — see the full model table, lifecycle status and replacement parts.
Omron CJ1W-ETN21 — CJ Ethernet Unit
SKU: CJ1W-ETN21USD 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.
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Product Overview
The Omron CJ1W-ETN21 is the CJ-series CPU-bus Ethernet unit. It is manufactured by Omron Corporation. Hengyixin Automation stocks this controller in Xiamen and ships within 3-5 business days to most Asian, European, and North American ports. Specifications on this page were checked against Omron's CJ-series Ethernet Unit documentation.
370 mA max on 5 VDC from the CJ backplane 31 x 90 x 65 mm slim body, same as CJ1W-ID262 / CJ1W-OD261 SMTP mail send and POP3 mail receive triggered by PLC bits Up to 4 ETN21 units per CJ / CJ2 CPU rack
Key specs: 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 370 mA max at 5 VDC from the CJ backplane per current Omron specifications; size the CJ power supply against this figure; Dimensions 31 x 90 x 65 mm (slim).
Key Features
- 370 mA max on 5 VDC from the CJ backplane
- 31 x 90 x 65 mm slim body, same as CJ1W-ID262 / CJ1W-OD261
- SMTP mail send and POP3 mail receive triggered by PLC bits
- Up to 4 ETN21 units per CJ / CJ2 CPU rack
- SKU: CJ1W-ETN21
- Series: CJ-series CPU-bus Ethernet Unit
Best-Fit Applications
- Non-Omron TCP/UDP device polled from a CJ scan via the socket service
- PLC-to-PLC FINS messaging between CJ and CS racks over the plant LAN
- Mail alert when a PLC flag, alarm, or threshold trips in the field
Buying Checklist
- Pick the CS1W-EIP21S instead for secure-comm features on a CS-series CPU bus.
- Pick the CJ1W-EIP21 instead when you also need EtherNet/IP tag data links to Allen-Bradley or third-party scanners.
- Pick the CS1W-ETN21 when the rack is CS-series (the ETN21E name on the same form factor slot).
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 | 370 mA max at 5 VDC from the CJ backplane per current Omron specifications; size the CJ power supply against this figure |
| 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 |
Manufacturer documentation
Omron's own product page, where the manufacturer's current specification and lifecycle information are published. We are an independent distributor and cannot mirror those documents; the link goes to Omron's site.
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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