705-5100-F21 Datasheet, PDF (4/52 Pages) Magnetrol International, Inc. – Enhanced Model 705 with PROFIBUS PA™ Digital Output

1.0 PROFIBUS PA^™ Overview
1.1 Description
PROFIBUS PA^™ 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 PROFIBUS PA^™ system can use the same physi-
cal wiring as an existing 4–20 mA device, fieldbus devices
are not connected point to point, but rather are mul-
tidropped and wired in parallel on a single pair of wires
(referred to as a segment).
• PROFIBUS PA^™ is a system that allows the user to
distribute control across a network. Fieldbus devices are
smart and actually maintain control over the system.
6234 feet (1900 meters) maximum
Power
Conditioner
PC
Terminator
Power Supply
Control Room
Terminator
Typical Fieldbus Installation
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 PROFIBUS PA^™ con-
siders the two wires as a network. The network can carry
many process variables as well as other information. The
Enhanced Eclipse Model 705PA transmitter is a
PROFIBUS PA^™ certified device that communicates with
the DPV1 protocol operating at 31.25 kbits/sec. The MBP
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 seg-
ment is 32 although this depends on the current draw
of the devices on any given segment.
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57-645 Eclipse Guided Wave Radar Transmitter - PROFIBUS PA^™