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Foundation Fieldbus is a
communication protocol and physical method to interconnect smart devices such as
temperature transmitters, pressure transmitters and valve actuators. The
physical layer conforms to
ISA SP50.02
and
IEC 1158-2 standards for fieldbuses.
Fieldbus
technology allows many smart devices to share one communication medium. The
digital communication signal is superimposed onto a DC carrier. This reduces the
amount of terminations to connect all the field devices to a host system and
allows greater flexibility for future additions of I/O points.
A Foundation Fieldbus device is addressable and can store and transmit data. The
devices can store values, track changes and use pre-set alarms to trigger. Based
on pre-defined tag names, host systems can read transmitter values such as
temperature and pressure to set values of a valve actuator. Digital signal
encoding is done using
Manchester BiPhase-L and error checking is done with the
CRC method. Foundation Fieldbus has two types of devices - A Basic Device
(BD) which reads inputs, track values and set outputs if programmed to do so - A
Link Active Scheduler (LAS) performs the same features as a BD and handles
network communication timing between all the active devices on the network.
More about Foundation
Fieldbus from Foundation Fieldbus website.
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