Product Details

The Yokogawa ACM22RS-422/485 is a high-performance Serial Communication Module designed for the CENTUM VP and CS 3000 Distributed Control Systems (DCS). This module provides two independent ports for RS-422 or RS-485 connectivity, allowing the DCS to interface directly with external PLCs, analyzers, and intelligent field instruments. We supply this unit as 100% brand new and original, ensuring stable and high-speed data exchange for your critical process automation network.

Product Overview

The ACM22RS-422/485 acts as a robust gateway for serial data, supporting industry-standard protocols such as Modbus RTU. By offloading serial polling tasks from the main Field Control Station (FCS), this module maintains system responsiveness even when managing dense networks of slave devices. It effectively bridges the gap between supervisory control and specialized third-party hardware, making it a vital component for oil and gas, chemical processing, and power generation facilities.

Technical Specifications

Engineering Advantages

• Optical Isolation Protection: The ACM22RS incorporates advanced optical isolation between the field-side circuits and the internal system bus. This hardware barrier prevents ground loops and protects the DCS from high-voltage transients often encountered in long-distance serial wiring.

• Dual-Port Integration Flexibility: Each module provides two independent ports. This allows engineers to manage two separate serial networks (e.g., one Modbus RTU loop and one proprietary loop) using a single card, significantly reducing the required rack space and system costs.

• Extended Transmission Range: The module supports reliable communication over distances up to 1200 meters using the RS-485 standard. This eliminates the need for signal repeaters in large-scale plant layouts where external instruments reside far from the control cabinet.

• High-Speed Data Throughput: With selectable baud rates up to 115.2 kbps, the ACM22RS handles rapid data polling for real-time monitoring. This ensures that the DCS captures process changes from intelligent devices with minimal latency.

• Rugged Industrial Durability: Designed for 24/7 operation in harsh environments, the card performs reliably in temperatures up to 60°C. The robust terminal block connectors ensure gas-tight, vibration-resistant field connections.

FAQs

Can I use Port 1 for RS-422 and Port 2 for RS-485 simultaneously?

Yes. The two ports on the ACM22RS operate independently. You can configure each port with its own communication standard, baud rate, and parity settings to match the specific requirements of your field equipment.

Does this module support Modbus ASCII?

The ACM22RS primarily targets Modbus RTU for high-efficiency industrial data exchange. However, compatibility with other serial protocols depends on the configuration of the Yokogawa DCS communication package. Most proprietary serial strings are manageable via the station builder.

What is the benefit of the optical isolation feature?

In industrial plants, long serial cables often pass near high-power motors or switchgear, which can induce significant electrical noise. Optical isolation ensures this noise does not reach the CPU or backplane, preventing system crashes and data corruption.

How do I set the terminating resistors for RS-485?

Terminating resistors are essential for long-distance RS-485 loops to prevent signal reflection. You typically set these resistors via hardware switches on the module or through external wiring at the terminal block, depending on the specific hardware revision.