Yokogawa ALR121-S01 CENTUM VP Serial Communication Module

Product Overview

The Yokogawa ALR121-S01 serves as a high-performance serial communication interface for the CENTUM VP and CS 3000 Distributed Control Systems (DCS). This module provides two independent ports supporting RS-422 and RS-485 standards, allowing the Field Control Unit (FCU) to manage long-distance data exchange with third-party subsystems. Whether connecting to Variable Frequency Drives (VFDs), PLCs, or smart analytical instruments, the ALR121-S01 ensures deterministic integration into the primary control environment. We supply this unit as 100% Brand New and Original to guarantee maximum reliability for your plant’s critical communication loops.

Part Number Breakdown

The ALR121-S01 utilizes a specific suffix logic to define its hardware revision and functional capabilities:

Technical Specifications

The ALR121-S01 maintains stable data throughput across long cable runs in high-interference environments.

• Communication Interface: RS-422/RS-485 (2 ports).

• Transmission Speed: 300 bps to 115.2 kbps.

• Connection Type: Supports 2-wire or 4-wire configurations (protocol dependent).

• Maximum Distance: 1,200 meters (approx. 4,000 feet) without repeaters.

• Isolation: High-grade galvanic isolation protects internal DCS circuitry.

• Power Consumption: 0.5 A at 5V DC (supplied via backplane).

• Condition: Guaranteed 100% Brand New Original.

Engineering Advantages

The ALR121-S01 addresses the core challenges of multi-vendor subsystem integration:

• Superior Noise Immunity: The differential signaling inherent in RS-422/485 protocols allows the ALR121-S01 to reject electromagnetic interference (EMI). This makes it the ideal choice for communication paths that run alongside high-voltage power cables or near heavy industrial machinery.

• Multi-Drop Network Capability: In RS-485 mode, this module supports multi-drop configurations. This allows engineers to daisy-chain multiple slave devices to a single port, significantly reducing the cost of wiring and maximizing the utilization of each module slot.

• Offloaded Protocol Management: The module features an internal processor that handles the serial protocol stack independently. This design prevents communication tasks from consuming the Field Control Unit’s (FCU) CPU cycles, maintaining the speed and determinism of your primary control loops.

• Seamless Redundancy: You can install two ALR121-S01 modules in a duplexed configuration. If the active module detects a hardware failure or a cable break, the standby unit assumes control of the serial link instantly, ensuring that critical subsystem data remains available to the operator.

FAQs

• Can the ALR121-S01 communicate with Modbus RTU devices?

  Yes. The ALR121-S01 provides the physical RS-485 hardware layer. When configured with the appropriate communication drivers in the CENTUM software, it seamlessly interfaces with any Modbus RTU slave device.

• What is the difference between the S01 and S00 versions?

  The S01 designation typically identifies a specific functional revision level required for compatibility with certain software versions of CENTUM VP. We recommend verifying your system's hardware profile to ensure the S01 matches your project's configuration database.

• How do I handle termination resistors for this module?

  For RS-422/485 networks, you must install a 120-ohm termination resistor at both ends of the segment to prevent signal reflection. The ALR121-S01 allows for easy termination at the module end via the standard connection procedures.

• Does this product come in original factory packaging?

  Absolutely. Every ALR121-S01 we ship is 100% Brand New and Original, arriving in its authentic Yokogawa box with factory seals and full serial number traceability.