Part of the Omron C200HW-PA & CS1W Legacy Power and Cabling series — see the full model table, lifecycle status and replacement parts.
Omron CS1W-EIP21S — EtherNet/IP Unit, Socket Services
SKU: CS1W-EIP21SUSD 290.00
CS-series EtherNet/IP unit with TCP/UDP socket services and four security features, 256 tag-data-link connections, 184,832-word capacity.
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Product Overview
The Omron CS1W-EIP21S is the EtherNet/IP communications unit for the CS1 series of PLCs. 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.
It adds an industrial Ethernet port to a CS1G, CS1H, CS1D, or NJ-series CPU, and sits as a CPU bus unit on the rack. The 'S' suffix distinguishes it from the discontinued CS1W-EIP21: the EIP21S adds a TCP/UDP socket service (for custom protocols like Modbus/TCP master / slave or barcode-reader polling) alongside EtherNet/IP, plus four security features — secure communication, user authentication, port-switch control, and IP packet filtering — that harden the unit against unauthorised access and malicious traffic on the plant network.
The unit ships with a 25-word CIO area and 100-word DM area reserved for control bits, status flags, target-node info, and IP configuration.
Key Features
- 100Base-TX Ethernet port
- Operates with CS1G, CS1H, CS1D, and NJ-series CPUs
- 25 CIO words / 100 DM words allocated per unit
- Mountable on CS1 CPU rack or expansion rack; up to 8 units per system
- SKU: CS1W-EIP21S
- Series: CS1W-EIP21S
Best-Fit Applications
- Plant network segmentation: enable IP filtering and user authentication on the CS1W-EIP21S to keep the office network off the control bus
- Retrofit of an existing CS1D cabinet adding native Ethernet without changing the CPU backplane
- CS1H system exchanging cyclic process data with 30 VFDs and an NB-series HMI over EtherNet/IP
Buying Checklist
- Pick CS1W-ETN21 when the cabinet only needs FINS messaging over Ethernet — it has EtherNet/IP support removed for cost.
- Pick CJ1W-EIP21S instead when the CPU is a CJ1 / CJ2 / NJ without CS1 expansion racks — the same logic and security features in a smaller form factor.
- Pick CS1W-EIP21S over the discontinued CS1W-EIP21 to get socket services and the four security features.
Technical Specifications
| Model | CS1W-EIP21S |
|---|---|
| Type | CS-series CPU Bus Unit; 100Base-TX EtherNet/IP |
| Tag Data Link Capacity | 184,832 words; 722 words / connection; 256 connections across 256 nodes |
| Higher-Level Protocols | EtherNet/IP, FINS/TCP, FINS/UDP |
| Socket Service | TCP / UDP open sockets via ladder (the 'S' feature) |
| Security Features | Secure comms, user authentication, port control, IP packet filter |
| CIO / DM Words | 25 CIO words + 100 DM words per unit (control + IP setup) |
| Power | 5 VDC from CS1 backplane; no external supply |
| Mounting | CS1 CPU or expansion rack; 8 units max per system |
| Compatible CPUs | CS1G / CS1H / CS1D and NJ-series with CS1 expansion |
| Operating Temperature | 0 to +55 °C |
| Approvals | UL, CSA, CE (RCM) |
FAQ for CS1W-EIP21S
What is the difference between CS1W-EIP21S and CS1W-EIP21?
The CS1W-EIP21S adds two things the older CS1W-EIP21 does not have: a TCP/UDP socket service (so the CS1 can act as a Modbus/TCP client / server or talk to barcode readers via standard sockets), and four security features (secure communication, user authentication, port-switch control, IP packet filter). Both units share the same EtherNet/IP tag-data-link engine, the same 256-connection capacity, and the same CS1 backplane form factor. The plain CS1W-EIP21 was discontinued — the CS1W-EIP21S is its specified replacement.
Can the CS1W-EIP21S work on a CJ-series rack or an NJ-series controller?
The CS1W-EIP21S is a CS-series CPU bus unit and physically only fits the CS1 rack or an expansion rack driven by a CS1 CPU. For the CJ1 / CJ2 family, use the CJ1W-EIP21S instead. NJ-series controllers (NJ101 / NJ301 / NJ501) accept the CS1W-EIP21S when they are set up to drive CS1 expansion racks — for native NJ communications, use the built-in EtherNet/IP port or an NX EtherCAT slave.
How is the unit configured?
Through CX-Programmer (for IP setup, target-node tables, and routing) or through the Network Configurator software (for tag data-link connections). The unit has a bank of rotary switches for node number and a small bank of DIP switches for IP-mode / boot-mode — set those before connecting the network cable. The configuration is saved in the unit's non-volatile memory so it survives power cycles.
How many tag data links can the CS1W-EIP21S handle?
256 connections of up to 722 words each, with up to 256 nodes total, for a combined 184,832 words. Tag-data-link data is refreshed per-connection (the connection-level consistency guarantee is per scan), so a single connection carrying the 722 words is delivered as a consistent batch even if the underlying network tries to interleave updates from other devices.
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