ABB TB800 Series Modules: TB826 Optical Media Converter SingleMode

Technical Dossier

Product Details And Specifications

ABB TB800 Series Technical Notes

The Evolution of TB800 Series Architecture

The TB800 series was introduced alongside the AC800M platform (launched circa 2000) as ABB transitioned from the older Advant OCS / MOD 300 architecture toward its current Symphony Plus and 800xA DCS ecosystem. Early TB800 modules used ST-type fiber connectors and supported single-channel simplex links. Subsequent hardware revisions introduced LC-type connectors, dual-channel redundant fiber paths, and extended temperature ratings for outdoor cabinet installations.

The TB826 specifically addresses SingleMode fiber (SMF) applications, supporting transmission distances up to 15 km — a critical requirement for large refinery or power plant layouts where I/O clusters are physically remote from the controller room. Multimode variants (e.g., TB825) cover shorter runs up to 2 km using 62.5/125 µm or 50/125 µm fiber. Later generations added diagnostic LED indicators for link status and receive-signal monitoring, reducing mean time to repair (MTTR) during field troubleshooting.

Compatibility note: TB800 series modules are mechanically and electrically compatible with the S800 I/O ModuleBus backplane. They are not interchangeable with the older S100 or S400 I/O families. When migrating from Advant OCS to 800xA, TB800 modules are retained in place provided firmware on the CI858 or CI854 communication interface is updated to the corresponding release.

TB800 Series Full Catalog & Functionalities (SKU List)

The following SKUs represent the verified TB800 series module range. Each entry reflects a distinct hardware variant with a defined functional role within the AC800M / S800 I/O architecture.

TB820: ModuleBus optical port module, multimode, 2 Mbit/s, ST connector, up to 500 m.
TB820V2: ModuleBus optical port module V2, multimode, enhanced diagnostics, LC connector.
TB821: ModuleBus optical port module, multimode, extended range, 62.5/125 µm fiber.
TB825: Optical media converter, multimode fiber, 2 km range, LC duplex connector.
TB826: Optical media converter, SingleMode fiber, up to 15 km range, LC duplex connector.
TB840: ModuleBus optical port module, redundant fiber, dual-channel, multimode.
TB840A: ModuleBus optical port module A-variant, redundant dual-channel, enhanced EMC rating.
TB841: ModuleBus optical port module, redundant fiber, SingleMode, long-distance.
TB845: Optical port module with integrated repeater function, multimode, 4-port.
TB850: S800 I/O cluster power distribution module, 24 VDC, DIN-rail mount.
TB851: S800 I/O cluster power distribution module, redundant 24 VDC input.
TB852: S800 I/O cluster termination module, standard backplane end terminator.
TB853: S800 I/O cluster termination module, extended backplane, 12-slot configuration.
TB860: ModuleBus modem, electrical RS-485 interface, for short-distance copper links.
TB861: ModuleBus modem, electrical interface, extended baud rate, point-to-point topology.
TB870: Optical repeater module, multimode, extends ModuleBus fiber segment length.
TB871: Optical repeater module, SingleMode, for ultra-long segment extension beyond 15 km.

Sourcing Hard-to-Find & Obsolete TB800 Series Parts

Several TB800 variants — including the TB820, TB840, and TB860 — have been discontinued by ABB and are no longer available through standard distribution channels. DriveKNMS maintains a dedicated inventory of new-surplus, refurbished, and tested-used TB800 series modules sourced from decommissioned plant assets, authorized liquidations, and global broker networks.

Quality Control for the TB800 Series Range

TB800 series modules incorporate fiber-optic transceivers and ModuleBus backplane interface logic that require specialized test procedures beyond standard power-on verification. DriveKNMS applies the following test protocol to all TB800 units prior to shipment:

Optical power output is measured using a calibrated optical power meter at the transmit port, verified against ABB's published TX power specification (typically –14 dBm to –8 dBm for multimode variants; –5 dBm to 0 dBm for SingleMode TB826). Receive sensitivity is tested by attenuating the input signal to the minimum specified threshold and confirming error-free ModuleBus frame transmission. Backplane connector integrity is inspected under magnification for bent pins, oxidation, or mechanical damage. ModuleBus communication is validated by loopback testing with a reference AC800M controller, confirming correct node addressing and cyclic data exchange. For redundant-channel modules (TB840/TB841), both fiber paths are tested independently and failover switching time is measured. All units are burned in at operating temperature for a minimum of 4 hours before final inspection.