Fairbanks FB2550 DAT SERIES DRIVER ACCESS TERMINAL - Manual (Page 89)

Section 4: Input/ Output
2/2013 89 51303 Rev. 1
5.8. FIELDBUS CONNECTIONS
The term FIELDBUS usually describes an all-digital two-way communications
system that interconnects measurement and control equipment such as sensors,
actuators and controllers.
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Fieldbus traces its beginnings in the automotive industry, where efforts to simplify
and reduce wiring resulted in a multiplexed CAN (Controller Area Network)
system of modules installed at various points of a vehicle.
WORKING EXAMPLE
Most cars have multiple controls on the door panel, such as power-window, power-
mirror, power-lock and power-seat controls. A Fieldbus Network combines all the
switch wires into a two wire communication bus. Pressing a switch closes a relay
that provides power to the window motor, sending a packet of data onto the
communication bus to adjust the passenger-side mirror.
5.8.1. OVERVIEW OF TERMS
There are currently four (4) different types of
Fieldbus Interfaces
listed as standard
accessories for the FB2550 DAT.
DEVICENET – A network system to
interconnect control devices for data exchange.
– It uses a differential serial bus, called
Controller Area Network (CAN), as the
backbone technology and defines an
application layer to cover a range of device
profiles.
CONTROLNET – An open Control Network in real-time, for high-throughput
applications.
MODBUS-TCP– Serial network communications in a master/slave
(request/response) type relationship using either ASCII or RTU (Remote Terminal
Unit) modes.
– Non-powered two-wire (RS-485) network, with up to 126 nodes, transfering a
maximum of 244 data bytes per node per cycle.
NOTE: See Section 9.3.1. Installing the Fieldbus for complete connectivity
information.
Typical Fieldbus Card installation.