The CJ1W-ETN21 module allows the PLC to communicate with other devices and systems over an Ethernet/IP network. It supports various protocols, including TCP/IP and UDP/IP, and provides features such as socket services and FTP client functions. The module also supports Modbus TCP/IP, allowing communication with Modbus-compatible devices.

By using the CJ1W-ETN21 module, the CJ series PLCs can connect to upper-level systems, human-machine interfaces (HMIs), and other Ethernet-based devices for data exchange and control purposes. It enables remote monitoring, data sharing, and integration of the PLC with the industrial network infrastructure.