The AFO4LE is an intermediate output unit that connects a host controller to field valves, indicator lights, and contactors; it is designed for the retrofit and replacement of legacy systems in power plants, metallurgical facilities, and chemical plants.

Specifications as below:

Power supply: 24V DC 

Electric current: 250mA

Output Channel: 16 relay-based passive dry contact outputs

Communication interface: RS485 with native Modbus RTU support

Storage and Processing: 512KB RAM + 32KB ROM; onboard independent MCU

Operating Temperature: -20°C to +60°C

Ingress Protection: IP30 (cabinet-mounted type); IP67 (partially ruggedized version)

Mounting Method: Standard DIN rail clip-on mounting; also supports insertion into DCS I/O rack backplane slots

Although this is an older product that has been discontinued, it still offers numerous advantages:

Passive dry-contact relay output compatible with both AC and DC loads, suitable for a wide range of field actuators;

Wide temperature tolerance and strong interference immunity, ensuring long-term stability in harsh heavy-industrial environments;

Maintains stability in offline mode, reducing the risk of process-related nuisance tripping;

Supports both DIN-rail and rack mounting, making it suitable for both retrofit and new installation projects;

Uses the universal Modbus protocol, enabling seamless integration with controllers from various manufacturers.