Yokogawa Electric Corporation ALR121-S51 S1 Serial Communication Module

The Yokogawa ALR121-S51 S1 Serial Communication Module enables RS-422/RS-485 serial links between DCS controllers and external devices, and is commonly installed in Yokogawa CENTUM DCS field control units and node units for subsystem communication. This 4-wire module supports half-duplex operation with point-to-point RS-422 and multipoint RS-485 connections, uses start-stop synchronization, and provides Modbus slave or subsystem communication at speeds from 1200 to 38400 bps, with typical transmission distances up to about 1200 m. Mounting compatibility includes AFV, ANB, and ANR series node/FCU units; current draw is roughly 0.5 A, enabling reliable data exchange between the DCS and external systems in industrial automation environments such as oil & gas, chemical plants, power generation, and manufacturing.