ABB TU849 3BSE042560R1 – S800 I/O Module Termination Unit for Reliable Field Wiring

The ABB TU849 (order code 3BSE042560R1) is a Module Termination Unit designed for the ABB S800 I/O family. From my experience, it’s the piece that makes field wiring neat and dependable while letting you hot‑swap the I/O module when needed. You might notice that it keeps the control cabinet tidy, reduces installation time, and typically helps cut downtime during maintenance because the field wires stay put on the base while the I/O module is exchanged.

Our Order Placement Process and Guarantees

• – Warranty: 365 days

• – Delivery time: 1 week for in‑stock items; no more than one month at the latest

• – Payment terms: 50% advance payment; full payment prior to delivery

– Express delivery: FedEx, UPS, DHL

Key Features

• Purpose-built for ABB S800 I/O – Hosts a single S800 I/O module and provides the field terminal interface.
• Front-access wiring – Clear terminal labeling helps technicians wire faster and reduce errors during commissioning.
• Hot-swap friendly – The module can typically be replaced without disturbing field wiring, which seems to be a big time-saver in many cases.
• Compact DIN-rail footprint – Keeps panel layouts dense and organized; ideal for brownfield upgrades and new builds.
• Shielding and grounding provisions – Supports clean signal routing when installed with proper earthing practices.
• HART transparency with compatible I/O – When paired with ABB HART-capable analog modules, the TU passes the HART signal through to asset tools.

Technical Specifications

Related or Supporting Products

• ABB S800 I/O modules (examples): DI801 / DI810 / DI820 (digital input), DO801 / DO810 (digital output), AI801 / AI810 (analog input, some with HART), AO801 / AO810 (analog output). Pair the TU849 with the module that matches your signal type and voltage level.
• Alternative S800 TUs: TU810/TU812/TU814 (non-redundant MTUs with different terminal densities and field power options), TU850-series (variants used in more specialized layouts). Differences are usually in terminal style, channel density, and power distribution features.
• Asset management tools: When using HART-capable AI modules, the TU allows HART pass-through for device configuration and diagnostics.

Installation & Maintenance

• Cabinet & mounting – Install on 35 mm DIN-rail in a ventilated enclosure. From my experience, keeping ambient below 50 °C and spacing the modules for airflow improves longevity.
• Wiring – Use properly sized conductors for your I/O load class; segregate analog, digital, and high-voltage lines to limit noise. Ensure a solid protective earth via the rail.
• Safety – De-energize circuits before servicing. Verify correct polarity and shield terminations, especially on analog channels and HART lines.
• Routine checks – Periodically re-torque terminals, clean dust with dry air, and visually inspect for loose strands. Firmware updates apply to the I/O module/controller, not the TU, but it’s good practice to align versions across the node.
• Spare strategy – Keeping one spare TU per panel row typically minimizes downtime during unexpected field damage.

Quality & Certifications

• Manufacturer’s quality system: ISO 9001 (typical for ABB factories)
• Product compliance: CE marking; UL/cUL listings and RoHS conformity are commonly applicable to S800 I/O components
• Warranty provided: 365 days from delivery

Real-world feedback: A system integrator recently swapped several digital input modules during a weekend outage; with TU849 bases already wired, changeover took minutes per point and loop checks stayed clean. That kind of practical efficiency is usually where these MTUs earn their keep.