ET-2251 is a 16-channel digital input (Wet/Dry Contact) module and each channel can function as a 32-bit counter. The module includes a built-in 2-port Ethernet switch, facilitating a daisy-chain topology. This feature offers flexibility in device configuration, simplifies installation, and reduces infrastructure costs. Additionally, the module provides EMS (EFT/ESD/Surge) protection and 3000 VDC I/O isolation to enhance noise protection capabilities in industrial environments.

Moreover, the module supports I/O Pair-Connection functionality, allowing the establishment of DI-to-DO pairing connections with the remote module via Ethernet. Once configured, local DI data can be written to remote DO channels in Push mode via Modbus TCP.

ET-2251 supports the MQTT protocol, serving as a publisher and subscriber of messages. When connected to an MQTT Broker Server, it can publish real-time statuses of I/O in the form of topics and receive messages from subscribed topics. If a disconnection occurs between the module and the broker during communication, its mechanism for reconnecting can automatically restore the connection. Additionally, its Keep-Alive Interval mechanism ensures a continuous connection with the broker.

ET-2251 supports the SNMP V2c specification, enabling it to transmit both module and I/O information to SNMP network management devices or software (SNMP Network Management Software). This allows administrators to monitor module status in real-time. Additionally, if the Trap function is enabled, the module can proactively send messages to administrators when there are changes in I/O statuses or during restarts, keeping them informed of channel statuses at all times.