YOKOGAWA ALR121-S51 S1 RS-422 RS-485 SERIAL COMMUNICATION MODULE

Description:

The Yokogawa ALR121-S51 S1 Serial Communication Module is used in distributed control systems for enabling RS-422/RS-485 communication between controllers and external devices. Commonly installed in Yokogawa CENTUM DCS field control units and node units for subsystem communication. Maintenance teams and system integrators use this part for establishing serial communication, replacing failed communication modules, or maintaining reliable data exchange in process control systems.

Applications:

The Yokogawa ALR121-S51 is commonly used in industrial automation environments where serial communication is required between DCS systems and external subsystems such as PLCs, analyzers, and third-party equipment. It is frequently applied in oil & gas, chemical plants, power generation, and manufacturing systems to enable Modbus communication and subsystem integration. The module supports both point-to-point and multipoint communication, allowing flexible connection architectures for industrial networks.

Technical Specifications:

• Manufacturer: Yokogawa
• Model / Part Number: ALR121-S51 S1
• Product Type: Serial Communication Module
• Interface: RS-422 / RS-485 (4-wire system)
• Communication Type: Half-duplex
• Connection Methods:
  – Point-to-point (RS-422)
  – Multipoint (RS-485)
• Synchronization Method: Start-stop synchronization
• Transmission Speed: 1200 / 2400 / 4800 / 9600 / 19200 / 38400 bps
• Communication Functions: Modbus slave communication, subsystem communication
• Transmission Distance: Up to ~1200 m (RS-422/485 typical)
• Mounting Compatibility: AFV, ANB, ANR series node/FCU units
• Current Consumption: Approx. 0.5 A
• Function: Data exchange between DCS and external systems

Common Replacements:

• Yokogawa ALR121-S50 Serial Communication Module
• Yokogawa ALR111 Serial Communication Module
• Yokogawa ALP111 PROFIBUS Communication Module