The Omron CJ1W-ETN21 is an Ethernet communication module designed for use with CJ series PLCs, providing high-speed and reliable network connectivity for industrial automation systems. This 100Base-TX Ethernet unit supports data transmission rates of 100 Mbit/s and is compatible with both unshielded twisted-pair (UTP) and shielded twisted-pair (STP) cables, ensuring flexible installation options. It can also operate as a 10Base-T unit when required, maintaining compatibility with various network infrastructures. The CJ1W-ETN21 can be mounted in either the CPU rack or an expansion rack, with up to four units supported per system for scalable network integration. This Ethernet module could possibly be utilized in automation systems across North America, Europe, Asia, and worldwide, offering stable communication performance and efficient PLC-to-network connectivity.