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EtherNet/IP Unit and Built-in EtherNet/IP Port Specifications Section 2-1
2-1 EtherNet/IP Unit and Built-in EtherNet/IP Port 
Specifications
2-1-1 General Specifications
The general specifications conform to those of the CS-series and CJ-series
PLCs.
2-1-2 Unit Specifications
CS-series EtherNet/IP Units
Note If tag data links are being used, use 100Base-TX. Otherwise, 10Base-T can
be used, but this is not recommended.
Item Specifications
Model number CS1W-EIP21
Type 100Base-TX (See note.)
Applicable PLCs CS-series PLCs
Unit classification CS-series CPU Bus Unit
Mounting location CPU Rack or Expansion Rack
Number of Units that can be 
mounted
8 max. (including Expansion Racks)
CPU Unit 
words used
Allocated CIO Area 
words (CPU Bus Unit 
words)
25 words/Unit (one unit number’s words)
These words contain control bits and flags, the target node PLC’s operating and 
error information, Unit status, communications status, registered/normal target 
node information, and FINS/TCP connection status.
Allocated DM Area 
words (CPU Bus Unit 
words)
100 words/Unit (one unit number’s words)
These words contain the IP address display/setting area
User-set area Any usable data area words
Target node PLC’s operating and error information, and registered/normal target 
node information
CPU Bus Unit System 
Setup
Not used.
Non-volatile memory within Ether-
Net/IP Unit (See note.)
The following settings are stored in the EtherNet/IP Unit’s non-volatile memory.
Note Unlike the regular Ethernet Units, the CPU Bus Unit Setup Area in the CPU 
Unit is not used for these settings.
1. Unit setup (communications settings for the EtherNet/IP Unit, such as the IP ad-
dress, DNS server settings, host name, baud rate, FINS/UDP settings, and FINS/
TCP settings)
2. Tag data link settings (device parameters)
Transfer 
specifica-
tions
Media access method CSMA/CD
Modulation method Baseband
Transmission paths Star form
Baud rate 100 Mbit/s (100Base-TX)
Transmission media Shielded twisted-pair (STP) cable
Categories: 100 Ω at 5, 5e
Transmission distance 100 m (distance between hub and node)
Number of cascade 
connections
There is no limitation when a switching hub is used.
Current consumption (Unit) 410 mA max. at 5 V DC
Weight 171 g max.
Dimensions 35 × 130 × 101 mm (W × H × D)
Other general specifications Other specifications conform to the general specifications of the CS-series