Yokogawa ALR121-S50 Serial Communication Module

Description

The Yokogawa ALR121‑S50 is a dual‑port serial communication module designed for CENTUM VP and ProSafe‑RS systems. It supports RS‑422/RS‑485 interfaces and provides Modbus slave and subsystem communication functions for stable industrial data exchange.

Hardware Specifications

Functional Description

The ALR121‑S50 module provides two isolated serial communication ports supporting RS‑422/RS‑485 4‑wire operation. It enables Modbus slave communication and subsystem data exchange within Yokogawa control architectures. As part of the ALR121 family, the S50 suffix indicates a standard‑type module with no explosion protection, suitable for general‑purpose control‑room environments. The module routes serial data to the control processor through the backplane, ensuring deterministic communication timing for subsystem integration.

Frequently Asked Questions

Q: What communication protocols does ALR121‑S50 support? It supports Modbus slave communication and Yokogawa subsystem communication functions.

Q: What does the S50 suffix mean? “S” = Standard type “5” = No explosion protection “0” = Standard environmental rating

Q: Can ALR121‑S50 be hot‑swapped? No. Serial communication modules must be inserted or removed only when the I/O segment is de‑energized.

Field Installation Guidelines

• Maintain shield continuity on serial communication wiring to reduce noise.
• Ensure correct polarity and wiring for RS‑422/RS‑485 4‑wire connections.
• Avoid routing serial lines near high‑current conductors to prevent interference.
• Verify backplane connectors are fully seated before energizing the system.
• Inspect terminal surfaces for contamination or oxidation prior to installation.