8WD4428-0BDOverview of Siemens 8WD4428 0BD AS Interface Adapter Element The Siemens 8WD4428 0BD is an AS Interface adapter element designed for use with the 8WD44 series signaling columns. It supports A B technology and allows connection of up to three signaling elements with a 24 V DC supply, enabling flexible and efficient industrial signaling solutions. Key Features of Siemens 8WD4428 0BD Adapter Element AS Interface Compatibility: Supports AS Interface A B