Description

The ABB TB845 is a high-reliability Termination Base engineered specifically for the ABB S800 I/O system within the 800xA architecture. Acting as the gateway for redundant PROFIBUS DP (or compatible Fieldbus) networks, this module provides the physical connection point where the fieldbus cable enters the I/O station. The TB845 features built-in termination resistors and redundancy switching logic, ensuring that if one communication line fails, the system seamlessly switches to the backup line without interrupting process control. Its rugged design protects against electrical noise, voltage spikes, and harsh environmental conditions, making it indispensable for maintaining continuous, safe operation in mission-critical industrial facilities. By simplifying wiring and ensuring signal quality, the TB845 reduces installation errors and enhances overall system availability.

Application Scenarios

An offshore oil platform utilizing an ABB 800xA system for wellhead monitoring experienced intermittent communication losses between the central control room and its remote S800 I/O cabinets located in hazardous zones. Diagnostics revealed that the original bus termination units were corroded due to salt spray, causing impedance mismatches and signal reflections on the redundant PROFIBUS line. The maintenance team replaced the faulty units with new ABB TB845 modules. Upon installation, the TB845’s robust sealing and gold-plated contacts restored perfect signal integrity. The redundant switchover mechanism was tested and confirmed functional, ensuring that even if one cable was damaged by future corrosion or vibration, the control system would remain online. This upgrade eliminated the communication alarms and secured the platform’s safety shutdown system against network failures.