HEIDENHAIN PROFINET - Manual (Page 10)

Introduction
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1.2 About PROFINET technology
PROFINET is the open industrial Ethernet standard of PROFIBUS
& PROFINET International (PI) for automation. PROFINET uses
TCP/IP and IT standards, and is in effect, real-time Ethernet. The
PROFINET concept features a modular structure so that users can
select the cascading functions themselves. They differ essentially
because of the type of data exchange to fulfill the partly very high
requirements of speed.
In conjunction with PROFINET, the two perspectives PROFINET
CBA and PROFINET IO exist. PROFINET CBA is suitable for the
component-based communication via TCP/IP and the real-time
communication for real-time requirements in modular systems
engineering. Both communication options can be used in parallel.
PROFINET IO was developed for real time (RT) and isochronous
real time (IRT) communication with the de-centralized periphery.
The designations RT and IRT merely describe the real-time prop-
erties for the communication within PROFINET IO.
To achieve these functions, three different protocol levels are de-
fined:
• TCP/IP for PROFINET CBA and the commissioning of a plant
with reaction times in the range of 100ms
• RT (Real-Time) protocol for PROFINET CBA and PROFINET IO
applications up to 1 ms cycle times
• IRT (Isochronous Real-Time) for PROFINET IO applications in
drive systems with cycles times of less than 1ms
Interfacing the peripherals devices such as encoders is imple-
mented by PROFINET IO. Its basis is a cascading real-time con-
cept. PROFINET IO defines the entire data exchange between
controllers (devices with "master functionality") and the devices
(devices with "slave functionality"), as well as parameter setting
and diagnosis.
PROFINET IO is designed for the fast data exchange between
Ethernet-based field devices and follows the provider-consumer
model. The configuration of an IO-System has been kept nearly
identical to the "look and feel" of PROFIBUS.