Knick Stratos 2221X pH Produktinformation Seite 109

PROFIBUS Technology
Defi nitions for PROFIBUS-PA
The bus protocol defi nes type and speed of the data exchange between master and
slave devices and determines the transmission protocol of the respective PROFIBUS
system. PROFIBUS-PA permits cyclic and acyclic services.
• Cyclic services are used for transmission of measurement data and actuating
commands with status information.
• Acyclic services are used for device confi guration, maintenance and diagnostics
during operation.
The device profi le defi nes the device class and typical functionalities with parame-
ters, ranges, and limit values.
The FISCO model developed for hazardous locations permits connection of several
devices to one common bus and defi nes permissible limits for device and cable
parameters.
Process control
Cyclic
services
Fig.: Typical confi guration of a PROFIBUS system with Stratos
Master
Class 1
PROFIBUS-DP
PROFIBUS-PA
Slave 1 Slave 2
Maintenance/Confi guration
Segment
coupler
Slave n
Master
Class 2
Acyclic
services
Bus termination
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