ABB TB850 (3BSC950193R1) – ModuleBus modem for S800 I/O expansion and segmentation

The ABB TB850, part number 3BSC950193R1, is commonly used in ABB S800 I/O systems as a ModuleBus modem for extending or segmenting the I/O bus between controller interfaces and remote S800 I/O islands. From my experience, teams deploy the TB850 when they need a clean way to bridge longer distances, improve bus robustness, or simplify cabinet layout without introducing process I/O at this node. It typically sits in the cabinet alongside CI modules and S800 terminal bases, providing a stable ModuleBus link with proper isolation and termination.

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• Warranty: 365 days
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Key Features

• ModuleBus extension/segmentation – Designed to link ABB S800 I/O segments where direct connection is impractical, helping organize larger cabinets or remote marshalling points.
• No process I/O – The TB850 handles bus interfacing only, which reduces configuration complexity and avoids address conflicts on the process side.
• Stable 24 VDC operation – Typically powered from the cabinet’s 24 VDC rail, keeping wiring consistent with the rest of the S800 ecosystem.
• DIN-rail mounting – Quick to install in crowded panels; you might notice that it aligns neatly with S800 terminal bases and CI modules.
• Supports robust bus topology – In many cases used in pairs to optimize distance, isolation, and termination on the ModuleBus.
• Service-friendly – From field feedback, swapping a TB850 during maintenance is straightforward, with minimal rework to harnesses.

Technical Specifications

Application Fields

The TB850 fits into ABB S800 I/O-based architectures found in process industries where remote I/O segmentation or distance bridging is needed:

• Oil & gas and petrochemical units, where I/O islands are spread across long pipe racks
• Power generation and utilities, segmenting I/O near turbines, boilers, or switchgear rooms
• Water and wastewater plants with distributed marshalling cabinets
• Pharma and fine chemicals, separating process, HVAC, and utility I/O segments
• Pulp & paper lines with long machine sections and segmented control zones

A maintenance lead in a combined-cycle plant told me they paired TB850 units to stabilize a long ModuleBus run between two buildings—bus diagnostics cleaned up, and nuisance faults practically disappeared.

Advantages & Value

• System compatibility – Purpose-built for ABB S800 I/O; avoids the guesswork of third‑party extenders.
• Reliability in harsh cabinets – Typically runs cool and steady on 24 VDC, with predictable behavior over time.
• Reduced downtime – Quick swap design; you rarely need to disturb neighboring terminal bases.
• Procurement certainty – Stable part code 3BSC950193R1 helps with spares planning and fleet standardization.
• Cost-conscious architecture – Extends existing ModuleBus rather than adding extra networking hardware.

Installation & Maintenance

• Environment – Install in a closed industrial cabinet (IP54 or better recommended), with adequate ventilation. Keep within typical 0–55 °C ambient.
• Wiring – Use shielded twisted pair for ModuleBus where specified. Maintain proper grounding and cable segregation from VFD power cables.
• Topology – In many cases, two TB850s are used (one at each end). Verify termination and bus segment lengths per ABB S800 guidelines.
• Power – Feed from a clean, protected 24 VDC supply with appropriate fusing; consider redundant feeds if the application is critical.
• Safety & ESD – De-energize before insertion/removal. Handle with ESD protection to avoid latent failures.
• Routine checks – Periodically inspect connectors, shield clamps, and cabinet filters; review controller diagnostics for bus health.
• Firmware/config – If applicable to your system version, keep controller and I/O firmware aligned; record any module replacements in the maintenance log.

Quality & Certifications

• Manufacturer quality standards: ABB production under ISO 9001
• Certifications typically associated with ABB S800 family: CE marking, RoHS compliance; UL/cUL recognition may apply depending on region
• Warranty: 365 days

Related/Supporting Components (for planning)

• S800 I/O terminal bases such as TU810/TU812/TU830 series (for process I/O modules)
• Controller interfaces for S800 I/O, e.g., CI801/CI840A/CI854A (depending on system)
• Alternative/adjacent bus components in the TB8xx family where applicable (e.g., TB810, TB820, TB840A) for different distance or media needs

Note: Specifications can vary slightly by system revision and plant standards. If you share your cabinet layout and distance requirements, I can sanity-check whether a paired TB850 setup is the best fit or if another S800 bus option makes more sense.