ABB S800 I/O 3BSE008538R1 TB807 Modulebus Terminator

Product Overview

TB807 (3BSE008538R1) is an ABB S800 I/O Modulebus terminator designed to ensure stable signal integrity at the end of the Modulebus communication line. It provides electrical termination to prevent reflections, signal distortion, and communication instability in distributed I/O architectures.

This component is widely used in ABB 800xA and S800 I/O systems deployed in power plants, oil and gas facilities, and continuous process industries. It plays a critical role in maintaining deterministic communication across high-density I/O networks. Without correct termination, Modulebus performance degrades and may cause intermittent system faults.

Engineers install TB807 to secure network stability in both new installations and retrofit expansions. It supports long-term reliability in harsh electrical environments where signal quality is sensitive to noise and impedance mismatch.

Functional Role in Modulebus Network

TB807 functions as a passive termination element for the ABB Modulebus communication line. It does not require configuration, addressing, or external power supply.

The device ensures correct impedance matching at the end of the bus segment. This prevents signal reflection that can affect data transmission between S800 I/O modules and controllers. It is a mandatory component in properly designed ABB Modulebus topologies.

The compact design allows direct installation into terminal positions within S800 I/O assemblies. It maintains system communication integrity without introducing latency or active processing overhead.

Technical Specifications

Technical FAQs

Is TB807 required in every S800 I/O system?
Yes, it is required at the end of each Modulebus segment to ensure signal stability.

Can TB807 be replaced with a generic resistor?
No, ABB specifies TB807 to match Modulebus electrical characteristics precisely.

What happens if TB807 is not installed?
Missing termination can cause communication errors, data loss, or unstable I/O behavior.

Is TB807 an active electronic module?
No, it is a passive termination device with no logic or power consumption.

Engineering & Installation Guide

Install TB807 only at the final node of the Modulebus segment. Incorrect placement in the middle of the bus will destabilize communication.

Ensure firm seating into the designated terminal position. Loose installation can introduce intermittent signal reflection under vibration conditions.

Maintain correct system topology before commissioning. Verify that only one termination exists per bus segment to avoid impedance imbalance.