Orion Instruments Jupiter 2xx FOUNDATION Fieldbus - Manual (Page 4)

4 57-649 Jupiter Magnetostrictive Transmitter - F OUNDATION fieldbus™
1.0 F
OUNDATION
fieldbus ™ Overview
1.1 Description
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 F OUNDATION 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).
• F OUNDATION 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 F
OUNDATION fieldbus ™
considers the two wires as a network. The network can carry
many process variables as well as other information. The
Enhanced Jupiter transmitter is a F
OUNDATION
fieldbus ™
registered device that communicates with the H1
F
OUNDATION fieldbus ™ protocol operating at 31.25
kbits/sec. The H1 physical layer is an approved IEC 61158
standard.
An IEC61158 shielded twisted pair wire segment can be as
long as 6234 feet (1900 meters) without a repeater. Up to
4 repeaters per segment can be used to extend the distance.
The maximum number of devices allowed on a Fieldbus
segment is 32 although this depends on the current draw
of the devices on any given segment.
Control Room
Power Supply
Terminator
6234 feet (1900 meters) maximum
PC
Terminator
Power
Conditioner
Typical Fieldbus Installation