Chapter 4. PROFINET System Operation
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PACSystems* RX3i & RSTi-EP PROFINET IO-Controller User Manual
GFK-2571N
4.1.1.2
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:
o
Real-
time Cyclic communication is used to periodically transfer the application’s input and output
data. Cyclic communication occurs each PROFINET IO production cycle.
o
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.
