ABB S900 Modules | S900 DX910S Digital I/O Module

Technical Dossier

Product Details And Specifications

ABB S900 Series: Comprehensive Module Range and Technical Overview

The ABB S900 is a distributed I/O system designed for integration with ABB's Symphony Plus (S+) DCS platform, formerly known as the Harmony and INFI 90 architecture. It is deployed extensively in heavy industrial environments including petrochemical refineries, nuclear power stations, pulp and paper mills, and offshore oil and gas platforms. The S900 system communicates over PROFIBUS DP and supports redundant fieldbus configurations, making it a standard reference architecture for safety-critical process control installations globally. Its modular backplane design allows field replacement of individual I/O modules without disrupting the entire node, a requirement in continuous-process industries where unplanned downtime carries significant financial and safety consequences.

The Evolution of S900 Architecture

The S900 system was introduced as ABB's answer to the growing demand for distributed, fieldbus-native I/O in the late 1990s and early 2000s. Early deployments used single-channel PROFIBUS DP communication with non-redundant power supplies. Subsequent hardware revisions introduced redundant fieldbus adapters (CI920S/CI930S), hot-swap module capability, and expanded analog channel density. The S900 architecture is compatible with ABB's AC800M and AC800F controllers via CI854/CI856 PROFIBUS master interfaces, as well as legacy Harmony controllers through gateway modules. As the installed base matured through the 2010s, ABB transitioned new greenfield projects toward the S800 and S800L I/O families and later the ABB Ability System 800xA platform. The S900 series is now in a mature/end-of-active-development lifecycle phase; ABB continues to supply spare parts and provide lifecycle extension services, but no new hardware variants are being introduced. For installations requiring long-term maintainability beyond 2030, ABB recommends migration planning toward System 800xA with S800 I/O, though S900 hardware remains available through authorized distributors and specialist spare parts suppliers.

S900 Full Catalog & Functionalities (SKU List)

The following SKUs represent the core module range of the ABB S900 distributed I/O system, organized by functional category. All models listed are verified S900-series hardware.

Digital I/O Modules

• DX910S: 16-channel digital input/output module, 24 VDC, configurable per channel, PROFIBUS DP interface.
• DI910S: 16-channel digital input module, 24 VDC, for discrete process signal acquisition.
• DI920S: 32-channel digital input module, 24 VDC, high-density discrete input for large I/O nodes.
• DO910S: 16-channel digital output module, 24 VDC, 0.5 A per channel, solid-state switching.
• DO920S: 32-channel digital output module, 24 VDC, compact high-density discrete output.
• DX920S: 32-channel mixed digital I/O module, 24 VDC, configurable input/output ratio per application.

Analog I/O Modules

• AI910S: 8-channel analog input module, 4–20 mA / 0–10 V, 12-bit resolution, HART-transparent.
• AI920S: 16-channel analog input module, 4–20 mA, high-density process variable acquisition.
• AI930S: 8-channel analog input module with HART communication support, field device diagnostics enabled.
• AO910S: 8-channel analog output module, 4–20 mA, 12-bit resolution, loop-powered field devices.
• AO920S: 16-channel analog output module, 4–20 mA, for high-density control output applications.
• AO930S: 8-channel analog output module with HART pass-through, supports smart valve positioners.

Communication & Fieldbus Adapter Modules

• CI920S: Single PROFIBUS DP fieldbus adapter, connects S900 I/O node to AC800M/AC800F controller.
• CI930S: Redundant PROFIBUS DP fieldbus adapter, dual-channel communication for fault-tolerant nodes.
• CI940S: PROFIBUS DP/PA link module, bridges DP and PA segments within the S900 node architecture.

Power Supply Modules

• PS910S: 24 VDC power supply module for S900 node, single-channel, 5 A rated output.
• PS920S: Redundant 24 VDC power supply module, dual-feed configuration for continuous-process installations.

Sourcing Hard-to-Find & Obsolete S900 Parts

As the S900 series has entered its mature lifecycle phase, procurement of specific modules—particularly early-revision DX910S, CI920S, and AI930S units—has become increasingly constrained through standard distribution channels. DriveKNMS maintains a dedicated inventory of S900 spare parts sourced from decommissioned plant assets, authorized surplus channels, and direct manufacturer relationships. For end-users operating S900-based DCS nodes in refineries, power generation facilities, or chemical processing plants, DriveKNMS provides lifecycle extension support including: verified functional testing of pulled units, cross-reference matching for discontinued part numbers, and supply of complete I/O node assemblies for rapid swap-out during planned turnarounds. Customers requiring long-term supply agreements for S900 modules are encouraged to contact DriveKNMS to discuss consignment stock arrangements and annual supply contracts.

Quality Control for the S900 Range

S900 modules incorporate a multi-layer backplane bus architecture with dedicated communication, power, and I/O signal planes. Quality verification for S900 hardware at DriveKNMS includes: backplane connector integrity inspection under magnification, PROFIBUS DP communication loopback testing at rated baud rates (up to 12 Mbit/s), channel-by-channel functional verification for all digital and analog I/O points, HART communication validation for AI930S and AO930S variants, and 48-hour burn-in testing under simulated load conditions. Power supply modules (PS910S, PS920S) are tested for output voltage stability, ripple, and redundancy switchover response time. All tested units are issued a DriveKNMS inspection certificate with test date, technician ID, and pass/fail records for each functional parameter.