YOKOGAWA AIP171 Vnet/IP-V net Coupler Unit

The Yokogawa AIP171 is a specialized Vnet/IP-V net Coupler Unit. It acts as a critical bridge between two different generations of Yokogawa control networks:

 the modern Ethernet-based Vnet/IP and the legacy coaxial-based V net.

1. Introduction

The AIP171 is designed to facilitate the seamless integration of legacy systems into modern architectures. 

In plants that are undergoing phased upgrades, the AIP171 allows new CENTUM VP stations (using Vnet/IP) to communicate directly with older CENTUM CS 3000 or CENTUM CS field control stations (using the traditional V net).

 It essentially "translates" the high-speed Ethernet packets of the modern network into the proprietary coaxial signals of the legacy bus, protecting the user's investment in existing hardware.

2. Technical Parameter Table

3. Related Models

The AIP171 is part of a networking suite used for system transitions:

AIP121: The standard V net coupler (coaxial to coaxial) for legacy bus extension.

VI702: The Vnet/IP interface card used in the Field Control Units.

VF702: The Vnet/IP interface card for the Human Interface Station (HIS) PCs.

YCB141: The 75 $Omega$ coaxial cable required for the V net side of the AIP171.

4. Product Advantages and Features

Phased Migration: Enables "Step-by-Step" plant modernization. You can upgrade your control room to CENTUM VP while keeping your old field wiring and I/O nests intact.

Bi-directional Communication: Data flows transparently between the two networks, allowing new operators' stations to monitor and control old field controllers.

High Reliability: Features dual-redundant power supplies and communication ports to ensure that the bridge between networks never becomes a single point of failure.

Protocol Transparency: No special programming is required; the DCS software views the legacy V net stations as if they were natively on the new network.

5. Application Cases

Refinery Expansion: When a refinery adds a new unit using modern Vnet/IP but needs it to interlock with an existing unit running on a legacy V net.

Control Room Consolidation: Moving all operator interfaces to a new, central Vnet/IP-based control room while leaving the physical controllers in remote satellite houses on V net.

Emergency Spares/Support: Used by maintenance teams as a gateway to connect diagnostic laptops (using Vnet/IP) to older segments of a plant for deep troubleshooting.

6. Other Models in the Same Series

AIP171-S1: Standard version for clean control room environments.

AIP171-S5: Version with G3 Conformal Coating, protecting the internal circuitry from corrosive atmospheric elements like hydrogen sulfide.

AIP172: A similar coupler but often used in specific configurations for redundant bus topologies or different power requirements.