ACM12 | Yokogawa | RS-422/RS-485 Communication Module

Yokogawa ACM12 RS‑422/RS‑485 Communication Module

The Yokogawa ACM12, also cataloged as the ACM12 communication module, provides serial connectivity for subsystem integration within Yokogawa control architectures. It supports both RS‑422 and RS‑485 interfaces, enabling point‑to‑point or multi‑point communication with up to 31 external devices.

Specifications

Functional Description

The ACM12 module enables deterministic serial communication for Yokogawa subsystems. RS‑422 provides stable point‑to‑point connectivity, while RS‑485 supports multi‑drop networks with up to 31 devices. Configurable baud rates (1200–19200 bps) allow flexible integration with legacy and modern equipment. Half‑duplex synchronization ensures reliable data exchange over long cable runs up to 1200 meters.

Frequently Asked Questions

Q: Can ACM12 operate in both RS‑422 and RS‑485 modes? A: Yes. The port is selectable between RS‑422 (point‑to‑point) and RS‑485 (multi‑point).

Q: What is the maximum supported cable length? A: Up to 1200 meters total cable length.

Q: How many external devices can be connected in RS‑485 mode? A: Up to 31 devices can be connected in multi‑point configuration.

Field Installation Guidelines

• Ensure correct polarity and wiring for RS‑422/RS‑485 connections.
• Maintain shield continuity to reduce electromagnetic interference.
• Avoid routing serial lines near high‑current conductors.
• Verify module seating in the Yokogawa nest before energizing.
• Confirm baud rate settings match connected devices.