E3A-JA3A-F11 Datasheet, PDF (4/60 Pages) Magnetrol International, Inc. – Liquid Level Displacer Transmitter

1.0 FOUNDATION Fieldbus^™ Overview
1.1 Description
FOUNDATION 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 an existing 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 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 fieldbus^™
considers the two wires as a network. The network can carry
many process variables as well as other information. The
E3 Modulevel transmitter is a FOUNDATION fieldbus^™ regis-
tered 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.
Power
Conditioner
PC
Terminator
Power Supply
Control Room
6234 feet (1900 meters) maximum
Terminator
An IEC61158 shielded twisted
pair wire segment can be as long
as 6234 feet (1900 meters) with-
out a repeater. Up to 4 repeaters
per segment can be used to extend
the distance. The maximum num-
ber of devices allowed on a
Fieldbus segment is 32 although
this depends on the current draw
of the devices on any given seg-
ment. See Figure 1.
Details regarding cable specifica-
tions, grounding, termination, and
other network information can be
found in IEC 61158 or the wiring
installation application guide
AG-140 at www.fieldbus.org.
Figure 1
Typical Fieldbus Installation
4
48-640 E3 Modulevel Displacer Level Transmitter - FOUNDATION fieldbus^™