Concept of Foundation Fieldbus
FOUNDATION™ Fieldbus is an all-digital, serial, two-way communication protocol that interconnects devices in the field such as sensors, actuators, and controllers.
FOUNDATION™ Fieldbus has the capability to distribute control applications across its network in the field. Furthermore it enables advanced diagnostics and asset management tools to be used resulting in higher plant availability. A typical Fieldbus installation provides connection from a network of field devices to a host system via a two way, serial communication link. The cabling and connections are arranged in a multi-drop fashion, requiring only a single pair wire with parallel connections to field devices. This is quite different from the traditional approach of connecting 4 to 20 mA devices to a DCS system using dedicated pairs of wires for each device.
Picture shown for typical fieldbus arrangement
Each Fieldbus run from the host system to the field is known as a segment. Each segment consists of a trunk or home-run running from the host system (DCS) and out through the processing plant with parallel connected spurs linking to field devices such as transmitters and control valves. Junction boxes are preferred to connect the trunk to the individual spurs.
A power supply connected to the trunk provides conditioned power to all devices on the Fieldbus segment.