Yokogawa ALR121-S50 RS-422/RS-485 Dual Serial Communication Module

Product Description

Overview

The ALR121-S50 is a high-performance Serial Communication Module designed for Yokogawa CENTUM VP and CENTUM CS 3000 systems. It enables reliable asynchronous serial communication between the DCS and external industrial devices such as PLCs, analyzers, and monitoring instruments. The module is suitable for demanding process environments where data integrity and system uptime are critical.

Key Features

Dual-Port Design

• Equipped with two isolated RS-422/RS-485 ports supporting both point-to-point (RS-422) and multipoint (RS-485) connections.

• Ports operate independently, allowing simultaneous communication with multiple devices or redundant network paths.

High-Speed Communication

• Supports baud rates from 1200 bps up to 115,200 bps, providing flexibility for varying device requirements.

• Capable of long-distance communication up to 1200 meters per port for extended field installations.

Protocol Compatibility

• Native Modbus RTU Master support ensures seamless integration with third-party devices.

• Flexible “no-protocol” configuration allows custom frame definitions for proprietary equipment.

Industrial Reliability

• Conformal Coating (S50 suffix) protects against moisture, corrosive gases, and harsh environmental conditions (G3 class per ISA-S71.04).

• Hot-swappable capability allows maintenance without powering down the system.

Seamless DCS Integration

• Fully mapped into Yokogawa Engineering Desktop, enabling direct use of external data as standard process tags.

• Dual redundancy support ensures uninterrupted operation in critical control loops.

Technical Specifications

Applications

Ideal for connecting external devices to CENTUM VP and CS 3000 systems in chemical, power, and petrochemical plants. Supports critical control and safety applications requiring reliable serial communication over long distances.

FAQ

Q: Can ALR121-S50 handle multipoint RS-485 communication?
A: Yes, it supports both point-to-point RS-422 and multipoint RS-485 connections.

Q: Can the module be replaced while the system is running?
A: Yes, it is fully hot-swappable, minimizing downtime during maintenance.

Q: What environments is the S50 variant suited for?
A: S50 indicates a standard type with conformal coating, suitable for corrosive gases and high-humidity conditions (ISA-S71.04 Class G3).