Yokogawa EH Series Modules - EH1*A

Name: Yokogawa EH Series Modules - EH1*A
Brand: Yokogawa

Model: EH1*A

Brand Yokogawa

Series EH Series

Model EH1*A

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Product Overview

Commercial availability is handled through direct RFQ, model verification and export-oriented follow-up rather than public cart checkout.

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Commercial Path

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Technical Dossier

Product Details And Specifications

Yokogawa EH Series Technical Notes

The Yokogawa EH Series represents a foundational generation of I/O and input modules deployed across global heavy industries — including petrochemical refineries, nuclear power facilities, steel mills, and offshore platforms. Built for integration within Yokogawa's CENTUM DCS architecture, EH Series modules established the hardware baseline that subsequent CENTUM CS and CENTUM VP generations evolved from. Installed base counts in the hundreds of thousands of nodes worldwide, making long-term parts availability a critical operational concern for plant asset managers and procurement teams.

The Evolution of EH Series Architecture

Q: How are RFQ terms confirmed?
A: Quantity, required condition, documentation needs, destination and sourcing route are confirmed during RFQ review before quotation.

As the industry transitioned toward FOUNDATION Fieldbus and HART-enabled I/O in the 2000s, the EH Series entered a maintenance lifecycle phase. Yokogawa ceased active production of most EH variants by the mid-2010s, shifting customers toward the CENTUM VP platform and its associated Vnet/IP communication backbone. However, the installed base remains substantial, and direct module replacement — rather than full DCS migration — remains the cost-effective choice for plants with 5–15 years of remaining operational life.

Key architectural characteristics of the EH Series include: fixed-slot backplane addressing, 16- and 32-channel I/O density options, 24 VDC field power compatibility, and hardware-based redundancy switching with sub-100ms failover. These specifications remain relevant for brownfield maintenance planning.

EH Series Full Catalog & Functionalities (SKU List)

The following models represent the most commonly sourced EH Series components. Each entry reflects verified part classifications based on Yokogawa technical documentation and field procurement records.

Analog Input Modules

EH1*A: 16-channel analog input module, 4–20 mA / 1–5 V, standard accuracy
EH1*B: 16-channel analog input, high-isolation variant for hazardous area FTA pairing
EH2*A: 32-channel analog input module, multiplexed scan, CENTUM EH backplane
EH2*B: 32-channel analog input, enhanced EMI shielding, refinery-grade
EH3*A: 8-channel high-accuracy analog input, ±0.1% FS, for critical process loops
EH4*A: Thermocouple/RTD input module, 16-channel, multi-sensor type selection
EH4*B: RTD-only input module, 8-channel, Pt100/Pt1000 compatible

Digital Input Modules

EH5*A: 32-channel digital input, 24 VDC, dry contact and wet contact selectable
EH5*B: 32-channel digital input, 120 VAC field voltage compatible
EH6*A: 16-channel digital input, high-speed pulse counting, up to 10 kHz

Analog Output Modules

EH7*A: 8-channel analog output, 4–20 mA, loop-powered, HART pass-through
EH7*B: 16-channel analog output, voltage output option (0–10 V), isolated

Digital Output Modules

EH8*A: 32-channel digital output, 24 VDC sourcing, 0.5 A per channel
EH8*B: 16-channel digital output, relay contact type, 2 A / 250 VAC rated

Communication & Controller Modules

EH9*A: Node controller module, manages up to 8 I/O slots, redundancy-capable
EH9*B: Communication adapter, RS-485 / Modbus RTU gateway for legacy field devices
EH0*A: Power supply module, 24 VDC regulated, 10 A output, redundant pair support

Sourcing Hard-to-Find & Obsolete EH Series Parts

DriveKNMS maintains a dedicated sourcing network for obsolete Yokogawa hardware, including the EH Series. Our inventory strategy combines three channels: (1) direct acquisition from decommissioned plant asset sales, (2) partnerships with certified refurbishment facilities that perform board-level restoration to OEM specification, and (3) cross-referencing with compatible successor modules where form-factor and signal compatibility allow substitution without DCS reconfiguration.

Q: How is condition confirmed before quotation?
A: Available condition, photos, test records and documentation are checked according to the requested model and sourcing channel before a formal RFQ response.

Quality Control for the EH Series Range

EH Series modules present specific testing challenges due to their age and backplane bus architecture. DriveKNMS applies a dedicated QC protocol for this product family:

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