YOKOGAWA V net Modules | YCB149 V net Converter Connector

Technical Dossier

Product Details And Specifications

YOKOGAWA V net Series: Comprehensive Module Range and Technical Overview

The YOKOGAWA V net communication bus is the proprietary high-speed token-passing network backbone of the CENTUM CS/CS 1000/CS 3000 and CENTUM VP Distributed Control Systems. Deployed across global heavy industry — including petrochemical complexes, nuclear power stations, oil refineries, LNG terminals, and continuous process manufacturing plants — V net operates at 10 Mbps over coaxial or optical fiber media and supports deterministic, real-time data exchange between field control stations (FCS), human interface stations (HIS), engineering workstations (EWS), and gateway nodes. Its redundant ring topology ensures fault-tolerant operation in safety-critical environments where unplanned downtime carries significant financial and regulatory consequences. Installed base spans several hundred thousand I/O points globally, making V net module availability a long-term operational requirement for asset owners running CENTUM-based infrastructure.

The Evolution of V net Architecture

V net was introduced with the CENTUM CS platform in the early 1990s as a replacement for the earlier ER bus used in CENTUM-XL systems. The original V net implementation used RG-6 coaxial cable with BNC connectors and supported up to 16 nodes per segment. With the release of CENTUM CS 3000 (circa 1998), YOKOGAWA extended V net to support optical fiber segments (V net/OFC) using ST-type connectors, enabling longer inter-node distances suitable for large refinery or power plant layouts spanning multiple buildings.

The CENTUM VP platform (introduced 2008) retained full V net backward compatibility while introducing Vnet/IP — an Ethernet-based successor running over standard 100BASE-TX infrastructure. Vnet/IP supports up to 64 domains and 256 stations per domain, significantly expanding system scale. Converter modules such as the YCB149 serve as the critical interface bridge between legacy V net coaxial segments and Vnet/IP Ethernet domains, enabling phased migration without full system replacement. This architectural continuity is the primary reason V net hardware remains in active procurement globally: brownfield sites cannot justify full DCS replacement and instead extend system life through targeted module substitution.

Compatibility constraints are significant: V net modules are not interchangeable with Vnet/IP-native cards without appropriate converter or gateway hardware. Bus termination, node addressing, and cable impedance (75 Ω coaxial) must be maintained precisely. Firmware versions on FCS processors must be validated against module hardware revisions before substitution.

V net Full Catalog & Functionalities (SKU List)

Communication Converters & Connectors

• YCB149: V net to Vnet/IP converter connector module for CENTUM VP migration interface
• YCB301: V net bus coupler unit, coaxial segment junction for multi-drop topology
• YCB311: V net optical fiber converter, coaxial-to-OFC media conversion module
• YCB321: V net/OFC repeater module for extended fiber segment distance
• YCB401: Vnet/IP interface card for CENTUM VP FCS integration

Field Control Station (FCS) Processor & Bus Modules

• CP451: CENTUM CS 3000 FCS processor card, V net node controller with dual-redundant support
• CP461: CENTUM VP FCS processor, Vnet/IP primary with V net legacy bus interface
• CP471: Enhanced FCS processor for CENTUM VP R6, dual Vnet/IP port
• EB401: ESB bus interface module, connects FCS internal ESB to V net backbone
• EB501: Enhanced ESB bus coupler for CENTUM VP high-density I/O expansion

I/O Modules (Analog & Digital)

• AAI141: 16-channel analog input module, 4–20 mA, HART-compatible, V net addressable
• AAI841: 8-channel analog input, high-accuracy ±0.1% FS, for precision process measurement
• AAO141: 16-channel analog output module, 4–20 mA, V net bus interface
• ADV151: 32-channel digital input module, 24 VDC, for discrete process signals
• ADV551: 32-channel digital output module, 24 VDC transistor output, V net addressable
• AMM12W: Multi-point analog input module, thermocouple/RTD, 12-channel, V net compatible

Power Supply Modules

• PW481: 24 VDC power supply unit for CENTUM CS/CS 3000 FCS node cabinet
• PW701: Redundant power supply module for CENTUM VP field control station

Sourcing Hard-to-Find & Obsolete V net Parts

YOKOGAWA formally transitioned its primary development focus to Vnet/IP with CENTUM VP R5 and R6 releases. Several V net coaxial-specific modules — including the YCB301, YCB311, CP451, and first-generation AAI/ADV series cards — are classified as discontinued (End of Manufacturing) by YOKOGAWA, with limited or no factory repair support. However, the installed base of CENTUM CS and CS 3000 systems in long-lifecycle industries (nuclear, refining, base chemicals) means demand for these components persists well beyond their official product lifecycle.

DriveKNMS maintains a dedicated inventory of tested V net modules sourced from decommissioned systems, authorized surplus channels, and controlled storage. All units are catalogued by hardware revision and firmware compatibility level. For end-users requiring long-term maintenance agreements or bulk spare parts packages for CENTUM CS/CS 3000 infrastructure, DriveKNMS provides documented traceability and pre-shipment functional verification. Inquiries for obsolete V net hardware should include the full part number, hardware revision (if known), and quantity required.

Quality Control for the V net Range

V net modules present specific test challenges due to their token-passing bus protocol and time-sensitive communication timing requirements. Standard bench power-on tests are insufficient to validate bus participation capability. DriveKNMS applies a structured test protocol for all V net inventory:

• Visual inspection of BNC/coaxial connectors and PCB for corrosion, cold solder joints, and capacitor condition
• Powered functional test using a CENTUM CS 3000 or CENTUM VP test node to verify V net token acquisition and data exchange
• For converter modules (YCB149, YCB311): bidirectional data throughput test across both media interfaces
• Firmware revision identification and documentation against YOKOGAWA compatibility matrices
• Burn-in cycle (minimum 24 hours) for processor and communication modules prior to shipment
• ESD-safe packaging with humidity indicator cards for long-term storage or international transit