Emerson PACSystems RX3i, User Manual

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RSTI-EP PROFINET I/O Controller User Manual Section 4
GFK-2571R May 2021
PROFINET System Operation 87
Figure 89: Application Relationship
Types of PROFINET Communications
PACSystems PROFINET Controllers use two types of PROFINET communication transfers:
real-time and non-real-time. The illustration below shows real-time communications as
solid lines and non-real-time communications as dashed lines.
Figure 90: Real-Time and Non-Real-Time Data Communications
• Real-Time (RT) communication: PROFINET real-time communication is used for time-
sensitive data. A PROFINET IO-Controller and PROFINET IO-Device use two types of real-
time communications to exchange data: cyclic communication and acyclic
communication:
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Real-time Cycl ic communication is used to periodically transfer the application’s
input and output data. Cyclic communication occurs each PROFINET IO
production cycle.
-
Real-time Acyclic communication is used to transfer non-periodic data such as
alarms. Acyclic communication occurs only when needed.
• Non-Real-Time (NRT) communication: PROFINET non-real-time communication is used
for less time-sensitive data such as configuration, parameterization, diagnostics, and
identification data.