YOKOGAWA ALF111-S51 FIELDBUS COMMS MODULE

Description:

The Yokogawa ALF111-S51 FOUNDATION Fieldbus Communication Module is used in distributed control systems for communication between controllers and field devices. Commonly installed in Yokogawa CENTUM DCS node units and field control stations for fieldbus network integration. Maintenance teams and system integrators use this part for enabling fieldbus communication, replacing failed communication modules, or maintaining reliable data exchange in process control systems.

Applications:

The Yokogawa ALF111-S51 is commonly used in industrial process control environments where FOUNDATION Fieldbus communication is required. It is frequently applied in oil & gas, chemical plants, power generation, and manufacturing systems to connect field instruments such as transmitters and valve positioners to the control system. The module functions as a Link Active Scheduler (LAS), coordinating communication timing and ensuring stable data exchange across fieldbus segments.

Technical Specifications:

• Manufacturer: Yokogawa
• Model / Part Number: ALF111-S51
• Product Type: FOUNDATION Fieldbus Communication Module
• Protocol: FOUNDATION Fieldbus H1 (low-speed voltage mode)
• Ports: 4 ports (1 segment per port)
• Transmission Speed: 31.25 kbps
• Function: Link Active Scheduler (LAS) for fieldbus communication
• Installation: Mounted on node units (ANB10/ANB11, AFV, A2FV series)
• Max Devices per Segment: Up to 32 devices (typical FF limit)
• Max I/O per Segment: Up to 48 points
• Withstanding Voltage: 1500 VAC (field-to-system)
• Weight: Approx. 0.4 kg
• Functionality: Data exchange between FCS and field devices (transmitters, valves)
• Configuration: Supports redundant DCS architectures

Common Replacements:

• Yokogawa ALF111-S50 FOUNDATION Fieldbus Module
• Yokogawa NFLF111 Fieldbus Communication Module
• Yokogawa AIP502 Communication Module