Communication
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PROFINET IO
Overview
This chapter describes the PROFINET IO communication protocol
for RETA-02. For detailed information on PROFINET IO
communication, refer to PROFINET specification Application
Layer protocol for decentralized periphery and distributed
automation v2.0.
Introduction to PROFINET IO
PROFINET IO is a fieldbus protocol that enables communication
between programmable controllers and distributed field devices in
Ethernet network. The protocol classifies devices into IO
controllers, IO supervisors and IO devices, which have a specific
collection of services.
PROFINET IO uses three different communication channels to
exchange data. The standard UDP/IP and TCP/IP channel is used
for parameterization and configuration of devices and for acyclic
operations. The Real Time (RT) channel is used for cyclic data
transfer and alarms. The third channel, Isochronous Real Time
(IRT) channel, is used e.g. in motion control applications (not
implemented in RETA-02).
PROFINET IO devices are structured in slots, sub-slots, which
can contain modules and submodules correspondingly. Device
can have almost any number of slots and sub-slots and they can
be virtual or real. Device specific data is represented in slot 0,
module and submodule specific data in subsequent slots and sub-
slots.
One of the benefits of PROFINET IO is the diagnostics and alarm
mechanism. Every module and sub-module provide alarm data to
the IO controller using the cyclic channel. Diagnostic data can be
read non-cyclically from the device by using record data.
Properties and services of a PROFINET IO device are described
in a GSD file that is written in GSDML (General Station Description
Markup Language). GSD file describes the device specific
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