ALR121-S00 | Yokogawa | CENTUM VP Serial Communication Module

Product Overview

The Yokogawa ALR121-S00 functions as a high-speed serial gateway for the CENTUM VP and CS 3000 Distributed Control Systems. This module provides two independent ports supporting RS-422 and RS-485 protocols, enabling the Field Control Unit (FCU) to manage data from remote subsystems such as PLCs, variable frequency drives (VFDs), and multi-drop sensor networks. By incorporating ISA Standard G3 protection, the ALR121-S00 maintains operational integrity even in harsh industrial atmospheres. We supply this unit as 100% Brand New and Original in factory packaging.

Part Number Breakdown

The ALR121-S00 suffix configuration defines its hardware capabilities and environmental resistance:

Technical Specifications

The ALR121-S00 manages long-distance serial communication with high noise immunity.

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

• Connection Method: Terminal block or D-sub depending on the base unit.

• Transmission Speed: Supports high-speed data polling for real-time subsystem integration.

• Environmental Protection: ISA Standard G3 (Corrosion resistance for harsh gases).

• Redundancy: Supports dual-redundant module pairing.

• System Interface: Plugs directly into Yokogawa FCS/FCU I/O slots.

• Condition: Guaranteed 100% Brand New Original.

Engineering Advantages

The ALR121-S00 addresses critical communication and environmental challenges in process plants:

• Corrosive Atmosphere Survival: Industrial sites often harbor corrosive gases like Hydrogen Sulfide (H2S) and Sulfur Dioxide (SO2). The ALR121-S00 features ISA Standard G3 compliant conformal coating. This protective layer prevents circuit board corrosion, significantly extending the module’s lifespan in chemical and wastewater treatment facilities.

• Long-Distance Multi-Drop Connectivity: Unlike RS-232, the RS-422/RS-485 interface on the ALR121-S00 allows for cable runs up to 1,200 meters. This enables the DCS to control devices located far from the main control room without requiring expensive signal repeaters.

• Superior Noise Immunity: The differential signaling of RS-485 inherently rejects electromagnetic interference (EMI). This allows the ALR121-S00 to maintain stable data flow even when installed near high-voltage motor starters or heavy-duty power cables.

• Bumpless Redundancy: When deployed in a duplexed configuration, the ALR121-S00 ensures continuous communication. If the active module detects a hardware failure, the standby unit assumes the serial stack instantly, preventing data loss or process upsets.

FAQs

• Can the ALR121-S00 communicate with Modbus devices?

  The ALR121-S00 provides the physical hardware layer for RS-485. You must configure the CENTUM software with the appropriate Modbus RTU/ASCII communication drivers to interpret data from your slave devices.

• Is the ISA Standard G3 coating necessary?

  If your facility handles chemicals or experiences high humidity, the G3 coating is vital. It prevents the "silver whiskers" and copper corrosion that typically lead to short circuits in standard industrial electronics.

• How many devices can I connect to a single port?

  Under the RS-485 standard, the ALR121-S00 can theoretically support up to 31 slave devices per port in a multi-drop configuration. However, we recommend calculating the total bus load and polling frequency to maintain optimal response times.

• Is this a refurbished or original part?

  We sell only 100% Brand New and Original hardware. Every ALR121-S00 ships in its original Yokogawa factory box with matching serial numbers for full traceability.