The Yokogawa ALP121 is a high-performance PROFIBUS-DP Communication Module designed for use within the CENTUM VP and CENTUM CS 3000 Distributed Control Systems (DCS).

It acts as a PROFIBUS-DP master, enabling the control system to exchange high-speed data with field devices, PLCs, and remote I/O.

1. Introduction

The ALP121 is an FIO (Field network I/O) module that integrates third-party PROFIBUS devices into Yokogawa’s unified control environment.

It is typically mounted on Field Control Units (FCU) or node units. By using a DP/PA coupler,

it can also communicate with PROFIBUS-PA field instruments, providing a bridge between advanced digital fieldbus diagnostics and the central DCS.

2. Technical Parameter Table

3. Product Advantages and Features

Dual Redundancy: Supports dual-redundant configuration. If one ALP121 module fails, the backup module takes over communication instantly without bumping the process.

Plug-and-Play Integration: Seamlessly works with Yokogawa’s Standard Builder Function and a dedicated PROFIBUS-DP Configurator.

G3 Environmental Protection: Often available with a “S1” or “S01” suffix, providing a conformal coating for protection against corrosive gases (ISA Standard G3).

Diagnostic Capabilities: Provides detailed status LEDs (RUN, ERR, ACT) and transmits device-level diagnostic alerts back to the Asset Management System (PRM).

Broad Connectivity: Compatible with a vast range of slave devices, including Siemens ET200 series, various frequency inverters, and motor protection relays.

ALP121

ALP121

4. Application Cases

Chemical & Refining: Integrating motor control centers (MCCs) and heavy-duty valves that use PROFIBUS for status and control.

Water Treatment: Connecting dispersed remote I/O stations across a facility to a central Field Control Station.

Power Generation: Managing complex auxiliary equipment like coal handling or soot-blowing systems that utilize PLCs with PROFIBUS interfaces.

Pharmaceuticals: Interfacing with specialized skid-based equipment (e.g., centrifuges or dryers) that require high-speed data exchange.

5. Related Models & Same Series

The ALP121 belongs to the communication-specific branch of the FIO family.

Other Models in the Same Series

ALP111: The legacy or alternative PROFIBUS-DP communication module for specific FIO configurations.

ALR111 / ALR121: Serial communication modules supporting RS-232C and RS-422/RS-485 (Modbus RTU).

ALE111: Ethernet communication module for Modbus TCP/IP or general Ethernet links.

ALF111: FOUNDATION Fieldbus™ (H1) communication module for digital field instruments.