Knick Stratos PROFIBUS 2221X Cond, User Manual

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PROFIBUS is a digital communication system that connects diff erent fi eld devices
over a common cable and integrates them into a control system. In the long term,
PROFIBUS will replace the 4–20 mA technology, which only supplies pure measured
values.
Advantages of the PROFIBUS technology are:
• easy and cost-saving cabling
• convenient operation over a central control station
• transmission, evaluation, and control of high amounts of data from fi eld device
to control station.
• devices installed in hazardous locations are confi gured and maintained from the
control station
PROFIBUS is the leading open fi eldbus system in Europe. Its application range
covers manufacturing, process, and building automation. As open fi eldbus standard
to EN 50170, PROFIBUS ensures communication of diff erent devices over one bus.
The PROFIBUS User Organization ( PNO) provides for further development and
maintenance of the PROFIBUS technology. It combines the interests of users and
manufacturers.
Variants and Basic Characteristics
PROFIBUS determines the technical and functional characteristics of a serial bus
system. There are several PROFIBUS variants:
PROFIBUS-DP (decentralized peripherals)
• is tailored for communication of automation systems and distributed peripherals.
It operates according to the RS 485 standard with transfer rates up to 12 Mbits/s.
PROFIBUS-PA (process automation)
• is dedicated to the process industry. It permits connection of sensors and actu-
ators to a common bus even in hazardous locations. PROFIBUS-PA has a transfer
rate of 31.25 kbits/s.
PROFIBUS distinguishes between two types of devices:
Masters
• control the data traffi
c on the bus. They send messages without external request.
Slaves
• are peripheral devices such as valves, drives, transmitters, and analyzers. They can
react acyclically to servicing, confi guration and diagnostic tasks of the master.
The central controller cyclically reads the measurement data with status.
PROFIBUS Technology