4
1.0 FOUNDATION Fieldbus
™
1.1 Overview
F
OUNDATION fieldbus
™
is a digital communications system
that serially interconnects devices in the field. A Fieldbus
system is similar to a Distributed Control System (DCS)
with two exceptions:
• Although a Foundation fieldbus
™
system can use the same
physical wiring as 4–20 mA device, Fieldbus devices are
not connected point to point, but rather are multidropped
and wired in parallel on a single pair of wires (referred to
as a segment).
• Foundation fieldbus
™
is a system that allows the user to
distribute control across a network. Fieldbus devices are
smart and can actually maintain control over the system.
Unlike 4–20 mA analog installations in which the two wires
carry a single variable (the varying 4–20 mA current), a dig-
ital communications scheme such as FOUNDATION field-
bus
™
considers the two wires as a network. The network can
carry many process variables as well as other information.
The ECLIPSE Model 706FF transmitter is a FOUNDA-
TION fieldbus
™
registered device that communicates with
the H1 FOUNDATION fieldbus™ protocol operating at
31.25 kbits/sec. The H1 physical layer is an approved IEC
61158 standard.
Details regarding cable specifications, grounding, termina-
tion, and other physical layer network information can be
found in IEC 61158 or the wiring installation application
guide AG-140 at fieldcommgroup.org.
BE57-646 ECLIPSE Guided Wave Radar Transmitter - FOUNDATION fieldbus
™
Control Room
Power Supply
Ter mi na t or
1900 meters (6234 feet) maximum
PC
Ter mi na t or
Power
Conditioner
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