The ABB 57310255‑AV DSBC172 is a bus interconnection unit designed for ABB Advant Master legacy DCS automation systems. It realizes stable signal routing and data forwarding between internal cabinet backplane and external expansion bus, supporting multi‑station interconnection for process control hardware. Adopting industrial‑grade euro‑card circuit structure, it is equipped with signal filtering and surge suppression circuits to cope with electromagnetic disturbance in thermal power, chemical and pulp‑paper production sites. Standard rack‑mount plug‑in design supports quick on‑site replacement to reduce unplanned downtime. Front‑panel LED indicators display power status and bus fault alarms in real‑time. As an essential vulnerable spare part for old‑generation DCS cabinets, each unit passes comprehensive full‑function testing before shipment for on‑site overhaul and spare‑parts stocking.