88UB01B panel features a key-operated switch and two status LEDs; it connects via a backplane connector to the monitoring station coupling module (88VU01) to manage the operating mode selection for the system's dual-redundant (A/B) remote bus architecture. It supports four bus operating modes—Bus A Active, Bus B Active, Automatic Redundancy Switching, and Maintenance Mode—selectable via the key switch positions. Panel LEDs provide a clear visual indication of the active remote bus. This module performs mode selection only—without participating in data processing—serving as a human-machine interface node within the redundant bus architecture;

it allows engineers to manually force a switch to the alternate bus during maintenance of one line, ensuring uninterrupted communication for the monitoring station.

Key specifications are as follows:

Power Supply: 24 VDC via backplane rack (sourced from the 88VU01 module)

Power Consumption: Very low; features only two LEDs; <2 W

Switch Type: 4-position rotary key switch with lock mechanism to prevent accidental operation

Switch Positions: 4 positions: Bus-A Only, Bus-B Only, Auto (Automatic Redundancy), Service (Maintenance Mode)

Status Indicators: 2 LEDs: Bus A Active, Bus B Active

Interface: Backplane edge connector; plugs directly into the monitoring station sub-rack; no external wiring terminals