Fairbanks FB2255 Series Instrument PC2255 PC Software Utility Program - Manual (Page 36)

01/13 36 51297 Rev. 1
Section 5: Fieldbus/Bluetooth
5.1. Fieldbus Installation
Fieldbus is a general term that describes an all-digital two-way communications
system that interconnects measurement and control equipment such as sensors,
actuators and controllers.
– Fieldbus traces its beginnings in the automotive industry, where efforts to
simplify and reduce wiring resulted in a multiplexed Controller Area Network
(CAN) system of modules installed at various points of a car
For example, many cars have multiple controls on the door, such as power-window,
power-mirror, power-lock and power-seat controls.
– To eliminate the thick bundle of wires of the older method, a driver's-door
module monitors all of the switches.
– If the driver presses the window switch, the door module closes a relay that
provides power to the window motor.
– If the driver presses the switch to adjust the passenger-side mirror, the
driver's door module sends a packet of data onto the communication bus of
the car.
– This packet tells a different module to energize one of the power-mirror
motors. In this way, most of the signals that leave the driver's door are
consolidated onto the two wires that form the communication bus.
As time has progressed, many different Fieldbus types have been developed, each
with different characteristics and specifications.
– Very simply, they serve as a Local Area Network (LAN) for instrumentation
used in automatic process control and manufacturing applications.
– The LAN is a digital, bi-directional, multi-drop, serial-bus communications
network used to link field devices (often referred to as “Nodes”), such as
controllers, transducers, actuators and sensors.
There are a number of different manufacturers that produce Fieldbus devices.
– Each produces different hardware interfaces, wiring and connector types,
speed, and the amount of bytes of data that can be exchanged on the
network, among other things.