Orion 2xx - Manual (Page 4)

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.
1 46-649 Jupiter Magnetostrictive Transmitter - F OUNDATION fieldbus™
Control Room
Power Supply
Terminator
6234 feet (1900 meters) maximum
PC
Terminator
Power
Conditioner
Typical Fieldbus Installation