Profinet Technology and Applications

Profinet Technology and Applications
PROFInet
Technology and Application
Introduction
Due to ever shorter innovation cycles for new products, the field of
automation is in a constant state of
change. In this context, the implementation of fieldbus technology in
recent years represents a major innovation. It enables the changeover from central to distributed
automation systems. As the world
market leader in this field,
PROFIBUS has now been setting
standards for 15 years.
Events in modern automation are
increasingly determined by information technology (IT) with established standards, such as TCP/IP
and XML. The integration of information technology into modern
automation has produced a considerable improvement in communication options between automation systems, as well as extensive
configuration and diagnostic options and remote service functions.
From the outset, these functions
have been an integral part of
PROFInet.
PROFInet is the innovative and
open standard for industrial
automation based on Industrial
Ethernet. PROFInet supports
easy implementation of solutions in factory automation and
Motion Control.
As well as utilization of IT technology, investment protection also
plays a key role in the PROFInet
concept. PROFInet enables integration of existing fieldbus systems, such as PROFIBUS, without
the need to modify existing devices. This protects existing investments of plant operators/
owners, machine/plant manufacturers and device manufacturers
alike.
PROFInet meets all automation
demands. PROFInet also incorporates years of know-how from the
PROFIBUS and Industrial Ethernet
world. The use of open standards,
the simple handling and the integration of existing devices determined
the
definition
of
PROFInet from the outset. PROFInet is now integrated in the
IEC 61158.
The continuous further development of PROFInet offers users a
long-term perspective for realization of their automation projects.
For plant/mechanical engineers,
the use of PROFInet minimizes the
cost of installation, engineering and
commissioning. For plant operators/owners, PROFInet enables
simple expansion of plants and offers high plant availability due to
autonomous subsections.
Furthermore, the method of certification established by PROFIBUS
International ensures a high quality
standard of PROFInet products.
The document gives you a detailed
explanation of how the tried and
tested PROFIBUS technology and
the established IT standards have
been implemented in PROFInet.
Contents
1. An overview of PROFInet........................... 1
5. Network installation ................................. 10
1.1
1.2
5.1
5.2
5.3
5.4
1.3
1.4
1.5
1.6
Distributed field devices (PROFInet IO). 1
Distributed automation (components
model) .................................................... 1
Communication ...................................... 1
Network installation ................................ 2
IT integration .......................................... 2
Fieldbus integration................................ 2
2. Decentralized field devices....................... 3
2.1
2.2
2.3
2.4
2.5
Scope of functions.................................. 3
Device models........................................ 3
Device description.................................. 4
Configuration and data exchange .......... 4
Diagnostics............................................. 4
3. Distributed automation .............................. 5
3.1
3.2
3.3
3.4
3.5
3.6
Technological modules .......................... 5
PROFInet components........................... 5
PROFInet Engineering ........................... 5
The component description (PCD)......... 6
The Connection Editor ........................... 6
PROFInet Runtime................................. 6
4. PROFInet communication.......................... 7
4.1
4.2
4.3
4.4
Standard communication with TCP/UDP7
Real Time communication ..................... 7
Communication with PROFInet IO........ 9
Communication between technological
modules.................................................. 9
Network topologies .............................. 10
PROFInet cabling ................................ 11
Connectors........................................... 11
Switches............................................... 12
6. IT integration............................................. 13
6.1
6.2
6.3
Network management.......................... 13
Web services ....................................... 13
OPC ..................................................... 14
7. Integration of fieldbus systems .............. 16
7.1
7.2
7.3
7.4
7.5
Migration strategies ............................. 16
Integration with proxies........................ 16
Integration of fieldbus applications ...... 16
PROFInet and other fieldbus systems. 17
Example of a modular machine ........... 17
8. Services offered by PI.............................. 18
8.1
8.2
8.3
Technology development..................... 18
Quality measures................................. 18
Technical support ................................ 19
9. Glossary .................................................... 20
1. An overview of
PROFInet
PROFInet is the innovative automation standard of PROFIBUS International for the implementation
of an integrated and consistent
automation solution based on Industrial Ethernet. PROFInet supports the integration of simple distributed field devices and timecritical applications in Ethernet
communication, as well as the integration of component-based distributed automation systems.
1.1 Distributed field devices
(PROFInet IO)
Distributed field devices are integrated through PROFInet IO. This
uses the usual IO view of
PROFIBUS DP, whereby the IO
data of field devices are cyclically
transmitted to the process image of
the PLC.
PROFInet IO describes a device
model that is based on the key features of PROFIBUS DP and comprises slots and channels. The
characteristics of the field devices
are described via a GSD (General
Station Description) on an XML basis.
The engineering of PROFInet IO
will be familiar to all system integrators of PROFIBUS DP, whereby
the distributed field devices are assigned a controller during configuration.
Figure 1: The architecture of PROFInet IO is similar to that of PROFIBUS DP
PROFInet on the basis of a component model is described via a
PCD (PROFInet Component Description). It is XML-based and can
be created using either the Component Generator of a manufacturer-specific configuration tool or
the PROFInet Component Editor.
The engineering of distributed
automation plants differentiates between the programming of the control logic of the individual technological modules (manufacturerspecific configuring tools) and the
technological configuration of the
overall plant, which determines the
communication relationships between the technological modules.
1.3 Communication
PROFInet uses different performance levels for communication purposes:
•
PROFInet transfers non-timecritical data, such as parameters, configuration data and
connection information over
the standard channel via
TCP/UDP and IP. This meets
the requirements for the connection of automation levels to
other networks (MES, ERP).
•
For transmission of timecritical process data within the
production plant, it uses the
real-time channel Soft Real
Time (SRT). It is implemented
as software based on available
controllers.
1.2 Distributed automation
(components model)
The PROFInet component model is
effective in distributed automation
plants. It is ideal for intelligent field
and automation devices with programmable functionality.
The component model describes
the autonomous modules of machines or plants as technological
modules. A distributed automation
system developed on the basis of
technological modules simplifies
the modular design of plants and
machines, thus considerably simplifying the re-use of plant and machine parts. This significantly reduces engineering costs.
Filling
Mechanical
Intelligent
field device
Control
software
Figure 2: Mechanics, electrics/electronics and software are combined to create technological modules
PROFInet Technology and Application, November 2003
1
•
For time synchronized applications, Isochronous Real Time
(IRT) communication is available which allows jitter accuracy of 1 µs at a clock rate of 1
ms.
1.4 Network installation
PROFInet network installations are
based on the specific requirements
for Ethernet networks in an industrial environment. They provide the
device manufacturer with clear
specifications for device interfaces
and the cabling required. The
"PROFInet Installation Guideline"
provides
plant
manufacturers/
operators with simple rules for the
installation of Ethernet networks.
1.5 IT integration
Network management covers all
functions for the administration of
PROFInet devices in Ethernet networks. This includes device and
network configurations and network
diagnostics.
•
1.6 Fieldbus integration
A key aspect for PROFInet is the
seamless transition from existing
fieldbus solutions, such as PROFIBUS DP, to Ethernet-based PROFInet. As far as the device/plant/
machine manufacturer and the end
user are concerned, this is an important protection of existing investments.
Integration of complete fieldbus applications: A fieldbus
segment represents a selfcontained component. The
representative of this component is the PROFInet device,
which at a lower level operates
a fieldbus such as PROFIBUS
DP. As such, the complete
functionality of a lower-level
fieldbus is stored in the proxy
in the form of a component.
This is then available on the
Ethernet.
PROFInet offers two methods of integrating fieldbus systems:
•
Integration of fieldbus devices
via so-called proxies: In this
case the proxy represents the
lower-level field devices on the
Ethernet. Using the proxy concept, PROFInet offers a fully
transparent transition from existing to newly installed devices.
For Web Integration, PROFInet
uses Ethernet-based technologies
and enables access to PROFInet
components by means of standard
technologies from the Internet.
To obtain an open link to other system worlds, PROFInet uses OPC
DA and DX.
Figure 3: PROFIBUS systems can be integrated in PROFInet using a proxy
2
PROFInet Technology and Application, November 2003
2. Decentralized field
devices
With PROFInet IO, integration of
the decentralized field devices is
implemented directly on the
Ethernet. For this purpose, the
master-slave access method, familiar from PROFIBUS DP, is converted to a provider-consumer
model. From a communication
point of view, all devices on the
Ethernet are treated democratically. However, the configuration
process is used to determine assignment of the field devices to a
central controller, whereby the familiar PROFIBUS user interface is
transferred to the PROFInet peripherals: the distributed peripheral
reads in the peripheral signals and
transfers them to the controller.
The controller then processes the
signals and transfers the outputs
on to the distributed peripheral.
2.1 Scope of functions
PROFInet IO distinguishes between three device types: IO-Controller, IO-Device and IO-Supervisor:
•
IO-Controller: Controller on
which the automation program
is run
•
IO-Device: remotely assigned
field device, which is assigned
to an IO-Controller
•
IO-Supervisor: programming
device/PC with commissioning
and diagnostics functions
Data can be transferred between
IO-Controller and IO-Devices over
the following channels:
•
cyclic IO data over the realtime channel
Figure 4: The consumer/provider model is used for communication relationships in PROFInet IO
•
event-controlled alarms over
the real-time channel
•
parameter assignment, configuration and reading of diagnostic information over standard channel on the basis of
UDP/IP.
To start, application relations (IOAR) are established between the
IO-Controller and the IO-Device on
the UDP/IP channel. It contains
several communication relationships (CRs) through which the configuration and IO data as well as interrupts are transferred. The IOController transfers the parameterization and configuration data of
the assigned IO-Devices over the
"Record Data CR". Cyclic transmission of the IO data is implemented over the "IO CR"; the
acyclic events are transmitted over
the "alarm CR" to the IO controller
and acknowledged. PROFInet
alarm types are unplug, plug in, diagnostics, status, and update
alarm.
Manufacturer-specific
alarms are also possible. High or
low priority can be assigned to
alarms.
2.2 Device models
A uniform device model is specified
for the PROFInet IO-Device, which
enables the configuration of modular and compact field devices. This
is orientated to the characteristics
of PROFIBUS DP and, for a modular field device, comprises slots for
the insertion of modules. These
modules are fitted with IO channels
which serve the input and output of
process signals.
Figure 6: The PROFInet IO device model is
similar to the PROFIBUS DP device model
This modular design ensures that
the existing PROFIBUS DP range
of IO modules can also be incorporated in PROFInet without requiring
any modification. This ensures investment protection for device
manufacturers
and
operators/
owners (e.g., spare parts inventory).
Each IO-Device is assigned a globally unique device ID within the
framework of PROFInet IO. This
32-bit Device-Ident-Number is broken down into a 16-bit manufacturer ID and a 16-bit device ID.
Figure 5: Functional scope of PROFInet IO
PROFInet Technology and Application, November 2003
3
The manufacturer identification is
assigned by PI. The device ID can
be individually assigned by manufacturers to suit their own product
development.
2.3 Device description
A PROFInet IO-Device is integrated in the configuration tool in
the same manner as a PROFIBUS
DP device, i.e. via a device description. The characteristics of an
IO device are described in a GSD
(General
Station
Description),
which contains all the information
that the field device requires:
•
Properties of the IO-Device
(e.g., communication parameters)
•
Plug-in modules (quantity and
type)
•
Configuration data of the individual modules (e.g., analog
input modules)
•
Parameters of the modules
(e.g., 4...20mA)
•
Error texts for diagnostics
(e.g., wire break, short-circuit)
The GSD is XML-based. The fact
that XML is an open, widespread
and accepted standard for describing data means availability of powerful tools and derived properties:
•
Creation
and
validation
through implementation of
standard tools
•
Integration
guages
•
Hierarchical structuring
of
foreign
lan-
The structure of the GSD corresponds to ISO 15745, comprising a
device-specific part with the configuration data and parameters of
the modules as well as a communication-specific part with transmission speed and connection system.
4
Figure 7: From configuration to data exchange
2.4 Configuration and data
exchange
The description files of the IODevices are imported to the configuration tool. The individual IO
channels of the field devices are
assigned peripheral addresses.
The peripheral input addresses
contain the received process values. The application program
evaluates these and processes
them. The application program
creates the peripheral output values and transmits them to the
process. In addition, the parameterization of the individual IO modules or channels is implemented in
the
configuration
tool,
e.g.,
4...20mA current range of an analog channel.
On completion of configuration, the
configuration data are downloaded
to the IO-Controller. The IO-Devices are automatically parameterized and configured by the IOController and then enter the cyclic
data exchange.
2.5 Diagnostics
PROFInet IO supports a multi-layer
diagnostics concept that enables
efficient error location and elimination.
When an error occurs, the defective IO-Device generates a diagnostics alarm at the IO-Controller.
This alarm calls up a corresponding program routine in the PLC program that enables a reaction to the
fault. If a device or module fault
means that it needs to be completely replaced, the IO-Controller
automatically carries out the
parameterization and configuration
of the new device or module.
The diagnostic information is hierarchically structured:
•
Slot number (module)
•
Channel number
•
Channel type (input/output)
•
Coded cause of failure (e.g.,
wire break, short-circuit)
•
Additional manufacturer-specific information
When an error occurs at a channel,
the defective IO device generates a
diagnostics alarm at the IO controller. This alarm invokes the call-up
of a corresponding error routine in
the control program. Once the error
routine has been implemented, the
IO-Controller acknowledges the error at the IO-Device. This acknowledgement mechanism ensures the
sequential processing of the error
in the IO-Controller.
PROFInet Technology and Application, November 2003
3. Distributed automation
Vendor independent
PROFInet Connection Editor
Vendor specific
Vendor specific
Developments in the field of automation have seen the creation of
modular plant or machines. This
structuring gave impetus to the further development of automation to
distributed automation systems.
PROFInet also has a solution for
this purpose, which is to break devices down into technological modules.
Vendor specific
Programming
Programming
Programming
Configuration
Configuration
Configuration
Parametrization
Parameterization
Parameterization
Parametrization
Parametrization
Parameterization
Vendor A
Vendor B
PROFIBUS
PROFIBUS
Vendor C
Fieldbus X
Figure 8: PROFInet is based on a multi-vendor engineering concept
3.1 Technological modules
In the goods manufacturing process, the function of an automatic
plant or machine is performed
through the defined interaction of
mechanical, electrical/electronics
and control logic/software. Working
on this principle, PROFInet defines
the mechanical, electrical/electronics and control logic/software
parts in functional terms to form a
technological module (see Figure
2).
3.2 PROFInet components
The representative of a technological module in the plant engineering
is the so-called PROFInet component. Each PROFInet component
has an interface, which contains
the technological variables that are
exchanged with other components.
The PROFInet components are
modeled with standardized COM
technology. COM is a further development of the object orientation
concept and enables the development of applications based on prefabricated components. A feature
of the components is that they form
autonomous units and can form relations with other components.
The components can be flexibly
combined like building blocks and
are easy to re-use, regardless of
their internal implementation. The
mechanisms for accessing the
component interfaces are uniformly
defined in PROFInet.
Granularity of the technological modules
When specifying the granularity of
modules it is important to consider
their re-usability in various systems
in the light of costs and availability.
The objective is to combine individual components as flexibly as
possible using the modular principle in order to create a complete
system. On the one hand, too fine
a granularity produces a technological view of the installation that
is more complex. This results in
higher engineering costs. On the
other hand, an all-too coarse of
granularity reduces the degree of
re-usability. This results in higher
costs for implementation.
The software components are created by the manufacturer of the
machine or plant. The component
design has had a major impact on
the lowering of engineering and
hardware costs and on the timerelated characteristics of the automation system. During definition of
Figure 9: Component generation is standardized with PROFInet
PROFInet Technology and Application, November 2003
a component, the granularity may
stretch from an individual device
through to a complete machine
with a multitude of devices.
3.3 PROFInet Engineering
A vendor-independent engineering
concept was created for the userfriendly configuration of a PROFInet system. On the one hand the
engineering concept can be used
to develop configuration tools able
to use multi-vendor components,
on the other hand it permits the
vendor- or user-specific expansion
of functions.
The engineering model distinguishes between programming the
control logic of the individual technological modules and the technological configuration of the complete system. A system-wide application is created in three stages.
Creating the components
The components are created as an
image of the technological modules
by the builder of the plant or installation. Programming and configuration of the devices is implemented
as before with the respective
manufacturer-specific tools. This
Figure 10: The connection information is downloaded to
the field devices after configuration
5
allows continued use of existing
application programs and utilization
of programmer and service personnel expertise.
Finally, the application software is
encapsulated in the form of a
PROFInet component, whereby a
component
description
PCD
(PROFInet Component Description) is created and imported to the
library of the Connection Editor.
Connecting the components
Using the PROFInet Connection
Editor, the created PROFInet components are taken from a library
and connected to form an application with simple clicks of the
mouse.
This connection with simple
graphical configuration replaces
the previous, labor-intensive programming of communication relationships. Programming requires
detailed knowledge of the integration and sequencing of communication functions in the device.
When programming, it must already be clear which devices will
communicate with each other,
when communication will take
place and over which bus system.
However, no knowledge of the
communication functions is necessary during configuration as these
are run automatically in the devices.
The connection editor draws together the individual applications
that are distributed throughout the
system. It works independently of
manufacturer, i.e. it configures
PROFInet components from different vendors.
Download
After connection of the components, the connection information
and the code and configuration
data of the components are
ables, such as their technological name, data type, and
direction (input or output)
•
Component libraries are formed to
support re-usability.
Figure 11: Communication is configured using the Connection Editor
downloaded to the PROFInet devices with a simple mouse-click.
Thus, each device knows all its
communication partners, communication relationships and exchangeable information. The distributed application can be implemented.
3.4 Component description
(PCD)
The PROFInet Component Description (PCD) is an XML file. It is
created using vendor-specific tools
assuming that these have a Component Generator. Alternatively,
you can create the PCD file using a
multi-vendor PROFInet Component
Editor, which can be downloaded
from the PROFIBUS website
www.profibus.com
The PCD file contains information
about the function and objects of
the PROFInet components. These
include the following:
•
description of components as
library elements: component
ID, component name
•
description of hardware: IP
address, access to diagnostic
data, download of connections
•
description of software functionality: assignment of software to hardware, component
interface, properties of vari-
Figure 12: The system view in the Connection Editor displays the connected components
6
buffer for component project
3.5 Connection Editor
A Connection Editor usually offers
two views: the system and the network view.
In the system view, the necessary
components are imported from the
library and placed on the screen,
and the various connections are
established. This creates the technological structure and its logical
relations within the system.
The topological structure of the
automation system is created in the
network view. In this case, the field
devices and programmable controllers are assigned to a bus system
and the device addresses are fixed
in accordance with the rules of the
underlying bus system.
3.6 PROFInet Runtime
The PROFInet runtime model defines functions and utilities that require cooperating automation components to fulfill an automation
task. It establishes and monitors
the connections between the PROFInet components configured by
the engineering tool. It sets up a
provider-consumer model in which
the provider generates and sends
data that the consumer receives
and processes.
Figure 13: The network view in the Connection Editor
shows the connected field devices
PROFInet Technology and Application, November 2003
4. PROFInet
communication
The Ethernet-based communication at PROFInet can be scaled. It
has three performance levels:
1. TCP, UDP and IP for non-timecritical data, such as parameter assignment and configuration,
2. Soft Real Time (SRT) for timecritical process data used in the
field of factory automation and
3. Isochronous Real Time (IRT) for
particularly sophisticated demands,
as for Motion Control applications.
These three performance levels of
PROFInet communication cover
the entire spectrum of automation
applications. Key features of the
PROFInet communication standard
include the following:
•
Coexistent use of real-time
and TCP-based IT communication on a single line
•
Standardized real-time protocol for all applications, for
communication between components in distributed systems
as well as between the controller and the decentralized field
devices
•
Scaleable real-time communication from performant to highperformant and time synchronized
The characteristics of the scaleable
and standardized communication
basis are one of the key strengths
of PROFInet. They ensure consistency right through to corporate
management level and fast response times in the automation
process.
Figure 14: The Ethernet-based communication for PROFInet can be scaled.
4.1 Standard communication
with TCP/UDP
PROFInet uses Ethernet and
TCP/IP as its basis for communication. As far as communication protocols are concerned, TCP/IP is a
de-facto standard in the IT landscape. However, with regard to the
interoperability of different applications, it is not enough to establish a
common TCP or UDP based communication channel (Layer 4) on
the field devices. The fact is, that
TCP/IP only provides the basis for
enabling Ethernet devices to exchange data through a transport
channel in local and distributed
networks. Additional specifications
and protocols, so-called application
protocols, are therefore required at
a higher level than TCP or UDP. Interoperability is only ensured if the
same application protocol is used
for all devices. Typical application
protocols are, for example, SMTP
(used for e-mail), FTP (used for file
transfer) and HTTP (used on the
Internet).
4.2 Real Time communication
of 5-10ms. The update time is the
time which passes when a variable
is created in a device application,
then sent to a partner device
through the communication systems, and is subsequently made
available to the application again at
this partner device.
Implementation of real-time communication should result in only
minimal loading of the processor
for the devices in order to ensure
that the processing of the application program continues to have priority.
Experience has shown that the
transmission time along the line
with Fast Ethernet (100 Mbps
Ethernet) or higher is negligible in
comparison to the execution time in
the devices. The time taken to
make the data available in the provider's application is not affected
by the communication. This also
applies to the processing of the received data in the consumer. This
means that any notable improvements in the update time, and
hence in the real-time response,
are to be achieved primarily
through suitable optimization of the
communication stack in the provider and the consumer.
In the field of factory automation,
real-time applications require update/response times within a range
Ethernet
Ethernet is standardized in IEEE 802.3. Specifications include access
technology, transmission procedures and transmission media for
Ethernet (10 Mbps), for Fast Ethernet (100 Mbps) and for Gigabit
Ethernet (1Gbps). PROFInet uses Fast Ethernet and Gigabit Ethernet.
Fast Ethernet for 100 Mbps is a compatible expansion of the 10 Mbps
Ethernet. Full duplex mode and switching are integrated and standardized in Fast Ethernet.
PROFInet Technology and Application, November 2003
Figure 15: Communication channels with
PROFInet
7
IP
Figure 16: Scheduling of communication system for IRT
Soft Real Time (SRT)
In order to satisfy real-time requirements in automation, PROFInet has an optimized real-time
communication channel – the Soft
Real Time channel.
This channel is Ethernet-based
(Layer 2). This solution minimizes
run times in the communication
stack appreciably and increases
performance with regard to the update rate of process data. Firstly,
the elimination of several protocol
levels reduces the message length,
and secondly, it takes less time before the transmission data are ready for sending i.e. are ready for
processing by the application. At
the same time the processor power
needed in the device for communication is greatly reduced.
Optimized data transmission
through prioritization
In PROFInet there is not only a minimized communication stack in
the programmable controllers; the
transmission of data in the network
is also optimized. In order to optimize results in these cases too, the
packets are prioritized in PROFInet
in accordance with IEEE 802.1Q.
Data flow between the devices is
then controlled by the network
components on the basis of this
prioritization. Priority 6 is the standard priority for real-time data. This
ensures priority handling over other
applications, such as Internet telephony with Priority 5.
Isochronous Real Time (IRT)
However, the aforementioned solutions are not sufficient for Motion
Control applications. These require
update rates of around 1 ms with a
jitter accuracy for the consecutive
TCP
TCP ensures that data transmission from sender to receiver is errorfree, in the correct sequence and complete. TCP is connectionorientated, i.e. a connection is established between two stations prior
to transmission of the data blocks and is disconnected again after
transmission. TCP has mechanisms for continuous monitoring of the
established connection.
Data transmission with the Internet Protocol (IP) represents a
non-secure package transmission (datagrams) between an IP
source and an IP destination.
Datagrams may be lost due to
interference on the transmission
channel or overloading of the
network, and they may arrive
several times or in a different
order than the one in which they
were sent. It can be assumed,
however, that any datagram received is correct. Due to the 32bit checksum of the Ethernet
packet, it is highly unlikely for
errors in the packet to go undetected.
cycles of 1µs for up to 100 nodes.
To meet these demands, PROFInet has defined the time-slotcontrolled transmission method IRT
on the Layer 2 Protocol for Fast
Ethernet.
Through the time synchronization
of participating devices (network
components and PROFInet devices) with the aforementioned accuracy, a time slot can be specified
in the network during which the key
data needed for the automation
task are transmitted. The communication cycle is broken down into a
deterministic part and an open part.
The cyclic real-time telegrams are
transported in the deterministic
channel, while the TCP/IP telegrams are transported in the open
channel. The process is comparable with the traffic on a freeway, of
which the left lane is reserved for
time-critical traffic (real-time traffic)
and prevents the other road users
(TCP/IP traffic) from switching to
this lane. Even congestion in the
right lane does not affect the timecritical traffic.
UDP
Like TCP, UDP ensures that data transmission from sender to receiver
is error-free, in the correct sequence and complete. However, in contrast to TCP, UDP is connectionless, i.e. each data packet is treated
as a single message and there is no transport acknowledgement. Because there is no timeout monitoring or connection buildup/cleardown,
UDP is better suited to time-critical applications than TCP. With UDP,
the data blocking and communication monitoring, which is implicit with
TCP, can be carried out at the application level e.g. over RPC (Remote Procedure Call).
8
PROFInet Technology and Application, November 2003
Implementation of the isochronous
data transmission is hardwarebased. An ASIC with this functionality covers the cycle synchronization and time slot reservation function for real-time data. The hardware-based implementation enables the required accuracy in the
required order of magnitude and
also relieves the processor in the
PROFInet device of communication
tasks. This frees up computing time
that can be made available for
automation task solutions.
4.3 Communication
with PROFInet IO
With PROFInet IO the UDP/IPbased RPC is used at startup for
the initiation of data exchange between the devices, parameter assignment of the distributed field devices and diagnostics. Due to the
open and standardized RPC protocol, HMI stations and engineering
systems (IO-Supervisors) can also
access PROFInet IO-Ddevices.
The PROFInet real-time channel is
then used for the transmission of
IO and alarms.
In a typical IO configuration, an IOController exchanges cyclic IO with
several decentralized field devices
(IO-Devices) via communication relationships. In each scan cycle, the
input data are sent from the assigned field devices to the IOController and, in reaction to this,
the output data are sent back to the
corresponding field devices. The
communication relationships are
monitored through the monitoring
of received cyclic messages. For
example, if the input frames fail to
arrive for 3 cycles, the IOController detects that the respective IO-Device has failed.
The data transmission layer of
PROFInet is defined in IEEE 802.3,
which describes the configuration
of the protocols and fault monitoring. A user data telegram comprises a minimum of 64 bytes and
a maximum of 1500 bytes. The
overall protocol overhead for realtime data is 28 bytes.
4.4 Communication between
components
In the PROFInet component view,
DCOM (Distributed COM) is specified as the shared TCP/IP-based
application protocol between PROFInet components. DCOM is the
expansion of COM (Component
Object Model) for the distribution of
objects and their interoperability in
a network. DCOM is based on the
standardized protocol RPC. As well
as accessing the engineering system, e.g. loading connections,
reading diagnostic data, device parameterization and configuration,
PROFInet also uses DCOM to establish connections and exchange
user data.
user configures whether user data
is exchanged over DCOM or the
real-time channel in the engineering system. While devices are setting up a communication they can
then agree if necessary to use a
real-time-capable protocol, because communication between
such plant/machine modules may
require real-time conditions which
cannot be satisfied by TCP/IP and
UDP.
TCP/IP and DCOM form the common "language" that can definitely
be used to start communication between the devices. The PROFInet
real-time channel is then used for
real-time communication between
the individual nodes in time-critical
applications. In the configuring tool,
the user can decide the quality of
service by setting the change rate,
i.e. whether the values are transmitted between the components
cyclically during runtime or only in
the case of change. Cyclic transmission is better in the case of high
change rates because the checks
for change and acknowledgment
result in a higher processor load
than sending in cyclic mode.
However, it is not necessary to use
DCOM for user data exchange between PROFInet components. The
Figure 17: PROFInet communication between PROFInet components and
PROFInet IO-Devices
PROFInet Technology and Application, November 2003
9
5. Network installation
The international standard ISO/IEC
11801 and its European equivalent
EN 50173 define an applicationneutral, standard IT network for a
building complex. The two standards are largely identical in content. Both assume that the buildings are put to office-like use and
claim to be application-neutral.
Neither standard takes account of
the specific requirements that need
to be met by Ethernet networks in
an industrial environment, e.g.,
•
Installation-specific cable routing
•
An individual level of networking for each machine/plant
•
Line network topologies
•
Rugged, industry-compatible
cables and connectors designed to meet special requirements with regard to
EMC, temperature, moisture,
dust and vibration
For this reason, the "PROFInet Installation Guideline" defines industry-standard cabling for Fast
Ethernet based on the specifications of IEC 11801.
Figure 18: Ethernet networks in the office world usually use a tree topology
5.1 Network topologies
Network topologies are orientated
to the requirements of the units to
be networked. The most frequently
used network topologies are star,
line, tree and ring structures. In
practice, a system tends to consist
of a mixture of these structures,
which are described below in
greater detail. These structures can
be implemented with either copper
or fiber-optic cables and can also
be used with PROFInet.
Tree
The tree topology results from joining together several stars to form a
network; a mixture of fiber-optic
and twisted pair cabling is possible
where necessary. It is used for dividing complex installations into
sub-installations.
Line
Star
The star structure is characterized
by a central signal distributor
(switch) with individual connections
to all the network's terminals. Ap-
Bürobereich
Office
sector
plications for star-shaped network
structures are areas of high device
density and short radius of expansion, e.g., small manufacturing
cells or a single production machine.
Fertigungs -and
Production
undfieldsector
Feldbereich
The line structure is implemented
by means of a switch near the connecting terminal or a switch integrated in the terminal.
It is primarily used in systems with
extensive structures, e.g., conveyor
systems, and for joining together
manufacturing cells.
feste basic
fixed
Grundinstallation
installation in
imthe
Gebäude
building
stark anlagenabhängige
cabling
extremely dependent
Verkabelung
on plant
Verlegung
Cable
laid in
in false
Zwischenböden
floors
anlagenspezifische
plant-specific
cable Kabelführung
routing
variablerdevice
variable
Geräteanschluss
connection am
at the
Arbeitsplatz
workplace
connection points are rarely changed
Ring (redundancy)
Vorkonfektionierte
Pre-assembled
device
Geräteanschlusskabel
connection cables
device connections are assembled locally
baumförmige
Networks
use Netzstrukturen
tree topology
networks
häufig
linienförmige
usually useNetzstrukturen
line topologies
und (redundant)
and
(redundante)ring
Ringstrukturen
topologies
Closing the ends of a line with an
additional connection produces a
ring structure.
großedata
large
Datenpakete
packages(z.B.
(e.g.Bilder)
images)
kleinedata
small
Datenpakete
packages(Messwerte)
(measured values)
mittlere Netzverfügbarkeit
medium
network availability
sehr hohe high
extremely
Netzverfügbarkeit
network availability
moderate Temperaturen
temperatures
extreme temperatures
Temperaturen
keine
no
moisture
Feuchtigkeit
Feuchtigkeit
possible
moisture
möglich
(IP65)
(IP65)
kaum Erschütterungen
virtually
no vibration
vibrierende
vibrating
machines
Maschinen
geringe
low
EMCEMV
load-Belastung
hoheEMC
high
EMVload
-Belastung
geringe
low
mechanical
mechanische
risk Gefährdung
risk of mechanical damage
kaum chemische
virtually
no chemical
Gefährdung
hazards
chemical load
chemische
Belastungen
due to
durch
öligeoroder
oily
aggressive
aggressive
atmospheres
Atmosphären
Ring topologies are used in systems with high availability requirements in order to protect against
broken lines or faulty network components.
Table 1: Differences between office and automation technology
10
PROFInet Technology and Application, November 2003
All the devices are connected
through an active network component. PROFInet uses switched network components. The specification of the network components
ensures simple installation. Transmission cables are equipped with
the same connectors at both ends
and are pre-assembled with the
same assignments. The maximum
segment length is 100m.
PROFInet cabling with
fiber-optic conductors
Figure 19: Ethernet networks in an industrial environment usually
use a line topology
5.2 PROFInet cabling
Industry-standard cables can be
subject to extreme mechanical
stress and are specially manufactured to meet these demands. PI
has defined a range of different cable types that are optimally designed to suit the respective industrial boundary conditions. Thanks
to sufficient system reserves, the
transmission length of an industrystandard installation can be created without restrictions.
Connectors and cables form a perfectly coordinated system. Only
components whose compatibility
has been tried and tested receive
the designation PROFInet component.
The requirements to be met by cabling at field level are similar to
those in PROFIBUS. Because stations are supplied not only with
data but also with 24 V, a hybrid
cabling structure is ideal. Hybrid
cables contain conductors for the
transmission of both signals and
power. Hybrid cables are available
as: Cu/FOC cable (2 optical fibers
for data transmission / 4 wires for
power transmission) as well as
Cu/Cu cable (4 wires for data
transmission / 4 wires for power
transmission).
Fiber-optic conductors are insensitive to electromagnetic interference
and usually permit more extensive
networks than symmetric copper
cables.
PROFInet cabling with symmetrical copper cables
Signal transmission over symmetrical copper cables (twisted pairs) is
performed in accordance with
100BASE-TX at a transmission
speed of 100 Mbps (FastEthernet). Two shielded copper
cables twisted in pairs (STP=
Shielded Twisted Pair) are defined
as the transmission medium.
Only shielded cables and connecting elements are allowed. The individual components have to satisfy
the requirements of Category 5 in
accordance with IEC 11801. The
entire transmission path has to
meet the requirements of Class D
in accordance with IEC 11801. Furthermore, PROFInet cables have a
cable cross-section of AWG 22 in
order to enable even complex cabling structures through minimum
damping. For this reason, the
specification of the PROFInet cables supports a modular setup,
which ensures an IEC 11801compliant structure on adherence
to simple installation rules.
Detachable connections are made
using an RJ45 or M12 connector
system. Device connections take
the form of jacks. The connecting
cables (device connection cables,
terminal cables) are equipped accordingly with connectors at both
ends, which can be pre-assembled
with the specified AWG 22 cable.
PROFInet can be operated using
multimode or single mode fiberoptic conductor lines. Signal
transmission is performed over
2 fiber-optic conductors in accordance with 100BASE-FX at a
transmission rate of 100 Mbps. The
optical interfaces are compliant
with
the
specifications
ISO/IEC 9314-3 (multimode) and
ISO/IEC 9314-4 (single mode).
For applications outside the
switchgear cabinet, the outer
sheath has to meet the requirements
(mechanical,
chemical,
thermal) imposed at the specific
point of use.
For multimode lines the maximum
segment length is 2 km, for single
mode lines it is 14 km.
5.3 Connectors
A major criterion for use in industry
is the handling of local connection
systems. Connectors for M12 as
well as RJ 45 are available for this
purpose. Local assembly of these
connectors is easy using standard
tools.
With PROFInet, the RJ45 with IP20
is used in switchgear cabinets. It is
compatible with the office connector. Connectors outside the switchgear cabinet need to take special
account of industrial requirements.
Types RJ45 with IP65 or IP67 or
type M12 are used in these cases.
Figure 20: Example of a RJ45 connector for IP20
PROFInet Technology and Application, November 2003
11
The RJ45 with IP65 / IP67 is enclosed in a rugged case with a
push-pull lock. Special models also
offer up to IP68 protection rating.
The hybrid connector is used where distributed field modules are
connected through a combined
connector with data and supply voltage. The RJ45 with IP67 has a
2-pair, shielded data line for communication and 4 copper conductors for the voltage supply.
A fully shock-hazard-protected
connector enables the use of identical connectors at both ends as the
pin-socket changeover is no longer
necessary due to the integrated
protection.
10BASE-TX (10 Mbps, CSMA/CD)
is also supported in order to ensure
compatibility with old systems or
single, old terminals or hubs.
Switches suitable for PROFInet
also support prioritized telegrams
according to IEEE 802.1Q, standardized diagnostic paths as well
as Auto Polarity Exchange, Autonegotiation Mode and Auto-CrossOver-Function. Port mirroring for
diagnostic purposes is optional.
Figure 21: Example of a RJ45 connector for IP 67
The RJ 45 connectors for PROFInet are versions 4 and 5 specified
in the draft of IEC 61076-3-106.
The M12 connector used for PROFInet is the shielded D-coded version specified in the draft IEC
61076-2-101.
The duplex DC connector system
in accordance with ISO/IEC 11801
is primarily used in the field of fiberoptics. The latter is described in
IEC 60874-14. Devices are equipped with the socket and the connection cable with the plug. It is
also possible to use BFOC/2.5 fiber-optic connectors in accordance
with IEC 60874-10.
12
Switches suitable for PROFInet are
designed
for
Fast-Ethernet
(100 Mbps, IEEE 802.3u) and full
duplex transmission. A switch
working in full duplex mode receives and sends data simultaneously at the same port. The use of
switches prevents collisions during
transmission. Hence there is no
loss of bandwidth due to the
Ethernet collision procedure. Network configuration is greatly simplified because there is no checking
of section lengths within a collision
domain.
Figure 22: Example of a RJ45 hybrid
connector for IP 67
5.4 Switches
PROFInet always uses switches as
network components. Switches are
devices positioned along the
transmission path between the
terminals to regenerate and selectively relay incoming signals. They
serve the structuring of networks.
They are based on the specifications of the ISO/IEC 15802-3.
Even if they comply with the aforementioned functionality, it is usually not possible to use switches
from the office sector. Special
switches are used for applications
in industrial environments. This is
firstly due to the fact that their design, both mechanical (IP degree of
protection, …) and electrical (24
Volt power supply, …), has been
specially developed for rugged industrial use. And secondly, they
need to meet the EMC demands of
machines in an industrial environment in order to ensure safe operation.
PROFInet Technology and Application, November 2003
for PROFInet. It enables assignment of IP parameters with
manufacturer-specific configuration/programming tools or in
cross-system engineering, e.g.,
in the PROFInet Connection
Editor. DCP is mandatory for
PROFInet devices, thus ensuring the uniform behavior of all
PROFInet devices.
6. IT integration
By using Ethernet as the communication medium, IT functions can also be integrated in PROFInet as
well as the automation functionalities described.
In conjunction with TCP/UDP and
IP, with Ethernet and Switching
technology comes an increased
demand for network management
than is the case in the fieldbus
world. A concept was therefore
specified for network management
in PROFInet in order to regulate all
technical aspects of the integration
of PROFInet devices in such networks. This concept covers the following main subject fields: network
infrastructure, IP management,
network diagnosis and time synchronization. The network management simplifies the administration and management of Ethernet
by using standard protocols from
the IT sector.
A further aspect is the use of Internet technologies in automation
technology. Within the framework
of Web Integration, PROFInet
specifies a concept that enables
access to PROFInet components.
This is implemented via web services based on standard Internet
technologies, such as HTTP, XML
and HTML.
6.1 Network management
Network management covers all
the functions required for the administration of a network, such as
configuration (assignment of IP addresses), error monitoring (diagnostics) or performance optimization.
IP management
PROFInet's use of TCP/UDP and
IP means it is necessary to assign
an IP address to network users,
i.e., PROFInet devices.
•
Address
assignment
with
manufacturer-specific configuration systems: This alternative
is required in case there is no
network management system
available. The DCP protocol
(Discovery and Basic Configuration) is specified
•
Automatic address assignment
with DHCP: the Dynamic Host
Configuration Protocol (DHCP)
is today the de-facto standard
for the assignment and management of IP addresses in
networks with network management systems in an office
environment. PROFInet has
elected to use these standards
and describes optimum use of
DHCP in a PROFInet environment. The implementation of
DHCP in PROFInet devices is
optional.
Diagnostics management
The reliability of network operations
takes very high priority in the network management. In existing networks, the Simple Network Management Protocol (SNMP) is now
the de-facto standard for the maintenance and monitoring of network
components and their functions.
SNMP is also ideal for monitoring
PROFInet devices with established
management systems. SNMP provides for both reading access
(monitoring, diagnostics) and writing access (administration) to a device.
Initially, only reading access of
device parameters was specified in
PROFInet. As with the IP management functions, SNMP is optional. When SNMP is implemented
in components, only standard
SNMP
data
is
accessed
(MIB 2).
Specific diagnosis of PROFInet
components is possible through the
mechanisms described in the
PROFInet specification. SNMP is
not intended to open up any further
diagnostic route in this connection
but should enable integration in
network management systems
which normally do not process
PROFInet-specific data.
PROFInet Technology and Application, November 2003
6.2 Web services
PROFInet does not just support the
use of modern Ethernet-based
technologies. PROFInet components can also be accessed by
web clients based on standard Internet technologies, such as HTTP,
XML, HTML or scripting.
In this case, data are transmitted in
a standardized form (HTML, XML)
and visualized using standardized
front ends (browsers such as Netscape, MS Internet Explorer, Opera, etc.). This enables integration
of data from PROFInet components in modern, multimediasupported information systems,
thus allowing PROFInet components to reap the benefits of Web
Integration in an IT landscape, e.g.,
the use of browsers as a uniform
user interface, flexible access to information from any number of clients, platform-independence of clients and reduced outlay for the installation and maintenance of client
software.
Functional properties
The design of PROFInet Web Integration focuses on commissioning
and diagnostics. Web-based concepts can be used particularly effectively within these fields of application:
•
No special tools are necessary
to access the components; established standard tools can be
used.
•
Global access makes it easy
for component manufacturers
to support users during commissioning.
•
The self-description of components enables access using
standard tools; no need for
configuration information.
Possible scenarios for Web Integration in the commissioning and
maintenance sector include: testing
and commissioning, overview of
device master data, device diagnostics, and system and device
documentation.
13
Information should be made available in both man-readable form
(e.g. with a browser) and machinereadable form (e.g. as an XML file).
With PROFInet Web Integration,
both options are consistently available. PROFInet Web Integration
also makes standardized XML
schemes available for certain information.
Daten
Data
in HTML
HTML-Seiten
pages
and
und over
über applets
Applets
Komponente: Füllen
Komponente: rinsing
Components:
Spülen
Technical properties
The basic component of Web Integration is the web server. It forms
the interface between the PROFInet object model and the basic
technologies for Web Integration.
Using PROFInet, Web Integration
can be scaled through the performance level and properties of
the web server. This means that
even simple PROFInet devices,
with only an "embedded web
server", can participate in the Web
Integration alongside a PROFInet
device via an "MS Internet Information Server" or "Apache Web
Server".
Web integration for PROFInet is
designed so that it can be made
optionally available on each device.
Certain functions are optional and
can be added depending on the
performance level of the device. It
is thus possible to implement
scaleable solutions that are optimized for the particular application.
The PROFInet-specific elements
can be seamlessly integrated in a
component's web implementation.
Using uniform interfaces and access mechanisms, creators of
technological components make
their technological data available
over the web. The namespace and
addressing concept specified in
PROFInet Web Integration enables
the addressing of PROFInet component model elements over the
web server. This supports creation
of dynamic web pages using current data from the component.
Scope
Web Integration is optional with
PROFInet, as it is arranged as an
independent element alongside the
PROFInet object model and neither
interferes with the other.
14
Figure 23: Web integration enables web access to PROFInet components
As far as the system architecture of
an automation system with PROFInet is concerned, it supports all architectural forms, particularly the
use of proxies for linking to any
fieldbuses. The specification includes corresponding models that
describe the relationships between
the PROFInet components, existing web components and the elements of PROFInet Web Integration.
Security
The specification of PROFInet Web
Integration is designed so that access to the PROFInet devices is
identical from the Intranet or Internet. This enables utilization of all
the advantages of Web Integration,
even if the device itself is not networked to the Internet. With this
type of local access, the risk of unauthorized access is extremely
small and comparable with modern
HMI systems.
For networking within larger factory
premises or over the Internet,
PROFInet Web Integration relies
on a graded security concept. It
recommends a security concept
optimized for concrete applications
with one or more upstream security
zones. This means that no structural restrictions are made to the
Web Integration concept, as the
security measures are always located externally to the PROFInet
devices. This not only relieves the
PROFInet devices, but also allows
the security concept to be optimally
modified to meet changing safety
demands while offering a constant
automation solution.
The best practice suggestions of
PROFInet Web Integration contain
scenarios and examples showing
how demand-dependent security
mechanisms can be implemented
for all PROFInet devices.
For example, it is possible to implement security mechanisms in
the transport protocols (TCP/UDP
and HTTP). The encoding, authentication and access management of
the web servers used are also scalable. Further-reaching security
elements such as application
gateways can be added for web
services if required.
6.3 OPC
The PROFInet component model
and OPC have the same technological basis in DCOM. This offers
user-friendly options for data communication between various parts
of the system.
OPC is a widely used interface for
exchanging data between applications in automation technology.
OPC supports the flexible selection
of multi-vendor devices and data
exchange between devices without
the need for programming.
OPC DX is not object-oriented like
PROFInet but tag-oriented, i.e. the
automation
objects
are
not
COM objects but names (tags).
PROFInet Technology and Application, November 2003
OPC DA (Data Access)
PROFInet
OPC DA (Data Access) is an industrial standard that defines a set
of application interfaces. This standardizes access to the data of
measuring and control devices, the
locating of OPC servers and simple
browsing in the name spaces of the
OPC server.
is an open system which specifies the runtime communication and engineering worlds within a PROFInet system and to lower-level PROFIBUS systems and other fieldbus systems. PROFInet offers the necessary real-time capability for automation applications through to highperformance and time synchronized Motion Control applications.
OPC DX
enables an additional, open data transfer between PROFInet and other
Ethernet-based communication systems, whereby OPC DX places low
demands on real-time communication.
OPC DX (Data Exchange)
OPC DX defines a communication
standard for the higher-level exchange of non-time-critical user
data at system levels between different makes and types of control
systems, e.g., between PROFInet
and Ethernet/IP. However, OPC
DX does not permit direct access
to the field level of a different system.
OPC DX is an extension of the
OPC DA specification and defines
a set of standard interfaces for the
interoperable exchange of data and
server-to-server communication in
Ethernet networks.
OPC DX is extremely useful for:
•
Users and system integrators
who want to integrate manufacturer-independent devices,
control systems and software
and implement access to
shared data in multi-vendor
systems, and
•
Manufacturers who want to offer products that build on an
open industry standard for interoperability and data exchange.
OPC DX and PROFInet
OPC DX was developed with the
aim of enabling at least a minimum
of interoperability between different
fieldbus systems and Ethernetbased communication protocols
without compromising the integrity
of the various technologies.
OPC DX was integrated in PROFInet in order to obtain an open link
to other system worlds. Integration
is achieved as follows:
•
Each PROFInet node can be
addressed as an OPC server
because the basic capabilities
already exist in the form of the
PROFInet Runtime implementation.
•
Each OPC server can be operated as a PROFInet node
through a standard adapter.
This is achieved through the
OPC Objectizer, a software
component that implements a
PROFInet device on the basis
of an OPC server in a PC. This
software component need only
be implemented once and can
then be used for all OPC servers.
The functionality and performance
of PROFInet is far greater than that
of OPC. In addition, PROFInet offers the required real-time capability for automation solutions. On the
other hand, OPC provides a higher
degree of interoperability.
Figure 24: Cross-system data exchange with OPC DA and OPC DX
PROFInet Technology and Application, November 2003
15
7. Integration of fieldbus systems
PROFInet offers a model for incorporating existing PROFIBUS and
other fieldbus systems in PROFInet. This means you can build up a
system consisting of a random mixture of fieldbus and Ethernet-based
subsystems. This enables the continuous transfer of technology from
fieldbus-based systems to PROFInet.
Engineering, HMI
Ethernet
Proxy
Intelligent
Field Device
Fieldbus X
•
User-owners want simple integration of their existing installations in a new PROFInet system.
•
Plant and machine manufacturers want to be able to use
their field-tested and documented device range in PROFInet
automation
projects
without the need for modification.
•
•
Integration of fieldbus devices
through proxies
•
Integration of fieldbus applications
7.2 Integration with proxies
The PROFInet proxy concept supports integration of existing fieldbus
systems that is simple and offers a
high degree of transparency.
Field Device
Drive
Figure 25: PROFIBUS and other fieldbus systems can be integrated in an automation device via a proxy or as a fieldbus application
On Ethernet, the proxy is the representative for one or more fieldbus
devices (e.g., on PROFIBUS). This
representative ensures transparent
communication between networks
(no tunneling of protocols). For example, it ensures transparent forwarding of cyclic data to the fieldbus devices.
Within the framework of PROFInet
IO, the DP slaves on PROFIBUS
are treated as IO devices. In the
component view, the intelligent DP
slaves are used as autonomous
PROFInet components. Within the
PROFInet connection editor, such
components cannot be distinguished from components directly
on Ethernet. The proxies support
transparent communication between devices on different bus systems.
7.3 Integration of fieldbus
applications
Device manufacturers want to
be able to integrate their field
devices in PROFInet systems
without any further outlay for
modifications.
PROFInet offers two methods for
connecting fieldbus systems:
PROFIBUS
Engineering,
HMI
7.1 Migration strategies
The high number of existing PROFIBUS systems means that for
reasons of investment protection it
is essential to support simple integration of these systems in PROFInet (migration), whereby the following distinctions can be made:
Controller
Figure 26: The principle of integrating
individual fieldbus devices using a
proxy
An entire fieldbus application can
be mapped as a PROFInet component within the framework of the
component model. This is important if an existing running plant is to
be expanded with PROFInet, whereby it does not matter which fieldbus is used to automate the plant
section.
In the case of PROFIBUS DP, the
proxy on the one side is the
PROFIBUS master, which coordinates the data exchange of the
PROFIBUS nodes and is the
Ethernet device with PROFInet
communication on the other. Proxies can be implemented, e.g., as
PLC, as PC-based control or as a
simple gateway.
Figure 27: The principle of integration of fieldbus applications
16
PROFInet Technology and Application, November 2003
In order for the existing plant to be
able to communicate with PROFInet, it is necessary for the fieldbus
master in the PROFInet component
to be PROFInet-capable. This
means that existing fieldbus mechanisms (e.g., PROFIBUS DP)
are used within the component and
PROFInet mechanisms are used
outside the component.
This migration option protects any
user investment in existing systems
and wiring (this may be the plant
operator/owner or plant manufacturer). It also safeguards any expertise already in user programs.
Thus PROFInet enables a smooth
transition to new system sections.
7.4 PROFInet and other fieldbus systems
Using the aforementioned integration methods, PROFInet therefore
supports integration of not only
PROFIBUS, but also of other fieldbus systems such as Foundation
Fieldbus, DeviceNet, Interbus, CCLink, etc. This is done by defining a
bus-specific image of the component interfaces for the data transmission options of the respective
bus and by saving it in the proxy.
This allows connection of any fieldbus to PROFInet in one fell swoop.
7.5 Example of a modular
machine
Figure 28 shows an example of a
modular machine from the food industry. The bottle-filling machine
consists of four modules. All essential steps of the overall application,
i.e., rinsing, filling, capping and
packaging are accommodated by
these four modules. On the one
hand this example demonstrates
the independent coexistence of
PROFIBUS and PROFInet in the
overall system. On the other hand
it highlights the simple integration
of existing machine sections.
In this example it is assumed that
the PROFIBUS system (rinsing and
filling) continues to be used, whereas the capping and packaging
units are to be renewed and extended on the basis of PROFInet.
The independence of communication procedures and the use of
proxy technology enable the existing PROFIBUS system to remain in
use fully unchanged. It is only necessary to connect the communication relationships between the
components in the engineering of
the new machine configuration.
The controller responsible for the
PROFIBUS system only needs to
be extended by an Ethernet module (hardware and software) and
the proxy functionality (software).
The proxy function ensures that the
PROFInet-specific view remains
encapsulated in the control system
as a technological module. All operations upstream from PROFIBUS
continue to run as before.
Figure 28: PROFIBUS DP can be integrated in PROFInet using proxy technology.
PROFInet Technology and Application, November 2003
17
8. Services offered by
PI
Optimum support from PROFIBUS
International is important if PROFInet is to become established on the
market as quickly as possible. A
powerful package of services and
products has been established to
achieve this goal.
8.1 Technology development
PROFInet IO
A specification is available for
PROFInet IO. This specification
contains a detailed description of
the device model and the behavior
of a field device in the form of protocols and communication operations (so-called state machines).
This type of description has already
proven effective with PROFIBUS
DP. The degree of detail in the
PROFInet IO specification enables
the software creation of a standard
stack of different stack suppliers.
It must be assumed that different
implementations will be offered by
a number of firms. For example,
Siemens offers an implementation
in the form of a development package.
Component model
As with PROFInet IO, the PROFInet component technology is available as a detailed specification.
The specification covers the aspects
communication,
device
model, engineering, network management, Web Integration and
fieldbus connection.
In addition to the specification,
PROFIBUS International also offers PROFInet software for the
component technology in the form
of source code.
The PROFInet software covers all
runtime
communications.
This
combination of specification and
operating
system-independent
software as source code enables
the simple and low-cost integration
of PROFInet in the broadest range
of device operating system environments.
18
Figure 29: The PROFIBUS International range of services
The PROFInet Runtime software is
configured so that it supports the
simple integration of existing application software in the runtime object model.
PROFInet already offers sample
portings for Win32, Linux, and
VxWorks.
The PROFInet Runtime software is
of modular design and consists of
various layers, each of which has
to be adapted to the system environment. The adaptations are limited to the porting interfaces leading to the various functional parts
of the environment, to the operating system (e.g., Win32) and to the
device application (e.g. PLC). A
porting manual is available to support porting operations. It is then
easier for the device developer to
understand the various steps required for porting.
8.2 Quality measures
In the development of PROFInet,
PROFIBUS International has ensured from the outset that the entire life cycle – from the specification of PROFInet to the systems
engineering stage – is supported
by measures which guarantee a
high level of quality in the various
phases.
QM of the specification and
implementation process
The PROFInet specification and
software are developed in a crosscompany working group, the
"PROFInet Core Team". The entire
development process from the first
registering of demands through to
the release of the PROFInet Runtime software is covered by a quality management system (QM).
The quality measures are set out in
a Quality Manual which is adapted
to the boundary conditions of the
cross-company development team.
This ensures that the source code
complies with the currently valid
rules of Quality Management.
The Quality Manual describes the
process model to be used and defines the terms, methods and tools
to be employed in the quality
measures. It also specifies the assigned areas of responsibility
throughout the quality process. An
important element in this respect is
Error Management. It includes an
unequivocal classification of errors
and a traceable error information
system.
PROFInet Technology and Application, November 2003
Figure 30: PROFInet Component Editor
Figure 31: The PROFInet Test Tool
Testing and certification
In order to ensure the correct interaction of all PROFInet devices and
a high product-quality, a certification system has been set up along
the lines of the proven system for
PROFIBUS products from the outset. At the heart of this process are
certification tests carried out by test
laboratories
authorized
by
PROFIBUS International. The test
for obtaining a certificate from one
of these test laboratories ensures
that the products comply with
specifications and are error-free.
Error information book
An error information book has been
set up at PROFIBUS International
so that errors and requests from
end-users and device manufacturers are systematically treated in the
runtime software. An error database for recording all errors and
their status has been made available for this purpose. The data
base entries are made in accordance with the rules of the quality
process.
8.3 Technical support
For PROFInet to be successful, it is
important to ensure rapid market
availability of a sufficient number of
PROFInet products from various
manufacturers.
Competence Centers
PROFInet Competence Centers
were established to support the
product development process. This
ensures optimum implementation
of the porting to the different operating systems and adaptation to
product-specific boundary conditions. The Competence Centers
help all interested companies to
build up know-how so that further
product developments can be expertly tackled in their own development departments without additional support.
PROFInet Technology and Application, November 2003
Other services offered by the
PROFInet Competence Centers include a telephone hotline and the
organization
of
target-grouporientated workshops.
Tools
Device manufacturers need a tool
for creating a component description of Ethernet devices in the form
of an XML file. PROFIBUS International offers the PROFInet Component Editor – similar to the GSD
Editor for PROFIBUS DP – on its
website www.profibus.com ready
to download.
To prepare newly developed products for certification, PROFIBUS International also offers a PROFInet
Test Tool that can be downloaded
from its website. The device manufacturer can use the PROFInet
Test Tool to carry out static tests
prior to certification.
19
9. Glossary
The network user that establishes a connection is called the
client. The user to which the connection is established is
called the server.
Component Object Model/
COM is a basic object model. It allows objects to make their
COM/DCOM Distributed Component Object
functionality available to other components. DCOM is an
Model
extension of COM for communicating through a network.
Functional extension of a vendor-specific configuration tool
Component
to generate an XML based PROFInet Component Description
Generator
(PCD).
Vendor-independent enginnering tool to configure plant wide
Connection
applications. The connection editor draws together the indiEditor
vidual applications that are distributed throughout the system.
Carrier Sense Multiple
A procedure for controlling access to the bus by various
CSMA/CD
Access/Collision Detection
users
Defines the assignment of IP parameters using vendorspecific configuration/programming tools or a by means of
DCP
Discovery and Basic Configuration
plant-wide Engineering, e.g. of a PROFInet Connection Editor.
Dynamic Host Configuration
De-facto standard for the dynamic issuing and management
DHCP
Protocol
of IP addresses from a pre-defined area
ERP
Enterprise Resource Planning
Protected trade mark of the Xerox Ethernet is standardized and serves to describe the physical
Ethernet
company (introduced in 1975)
and Data Link level of a network.
FTP
File Transfer Protocol
Protocol for the transmission of files; based on TCP/IP
Interconnects two or more networks with even different
physical layers. Provides the necessary translation, both in
Gateway
terms of hardware and software.
A GSD (General Station Description) contains an XML-based
description of IO-Device’ properties like communication paGSD
General Station Description
rameter as well as number, type, configurations data, parameter and diagnostic information of modules.
The visible face of a system on the control and monitoring
HMI
Human Machine Interface
platform
HTML
Hypertext Markup Language
Document description language
HTTP
Hypertext Transfer Protocol
Application protocol that is used in Internet.
Controller at PROFInet IO on which the automation program
IO-Controller
is run.
Remotely assigned field device, which is assigned to an IOIO-Device
Controller.
Programming device/PC with commissioning and diagnostics
IO-Supervisor
functions at PROFInet IO
Connectionless protocol for the transmission of data
IP
Internet Protocol
messages; IP is often used in conjunction with TCP in order
to ensure safe data transmission.
Isochronous Real Time channel for particularly sophisticated
demands, as for Motion Control applications (time synchroIRT
Isochronous Real Time
nized applications). The realization as hardware allows clock
rates of 1 ms and lower at a jitter accuracy of 1 µs.
MES
Manufacturing Execution System
A data carrier that has a time-variable status and whose
Object
responses to incoming messages are defined
A mechanism for the creation and editing of documents
containing objects which were created by various
OLE
Object Linking and Embedding
applications.
Introduced in 1996; the generally recognized interface for
OPC
OLE for Process Control
exchanging data between Windows-based applications in
automation technology.
Industrial standard that defines access to the data of
measuring and control devices, the locating of OPC servers
OPC DA
OPS Data Access
and simple browsing in the name spaces of OPC servers
based on client/server communication.
Client/Server
20
Principle of establishing
connections
PROFInet Technology and Application, November 2003
OPC-DX
PCD
PROFInet
Component
Editor
Proxy
RPC
Runtime
SNMP
SRT
Switch Technology
TCP
UDP
XML
Standard for the Ethernet-based exchange of non-timecritical user data between multi-vendor automation systems
based on server-to-server communication
XML-based file containing information about functions and
PROFInet Component Description
objects of PROFInet components.
Stand alone tool to generate XML-based PROFInet Component Description (PCD) files; available for download from the
website www.profibus.com.
Representative of an object in the object model; it makes the
PROFInet view available on a field device or field device
group. On Ethernet, the proxy is the representative for one or
more PROFIBUS devices.
Defined call interface for calling up programs in remote
Remote Procedure Call
devices.
Designation for the status of a system "operation mode" as
Runtime
opposed to the system status "in the engineering phase"
Simple Network Management
A TCP/IP based communications protocol for the
Protocol
maintenance and monitoring of networking components
Real-time channel for time-critical process data used in the
field of factory automation. It is implemented as software
Soft Real Time
based on available controllers.
Technology for dividing an Ethernet network into different
sub-networks; serves to prevent collisions and improve
utilization of the bandwidth.
Communications protocols for transferring data between local
Transmission Control Protonetworks. TCP is connection-orientated and is used for
col/Internet Protocol
communication on the Internet. TCP is usually used in
conjunction with IP (TCP/IP)
Transport protocol with broadcast properties. Ideal for the
User Datagram Protocol
transmission of time-critical I/O data
Extensible Markup Language
Definition of a structured data description
OPC Data Exchange
More information as well as PROFIBUS and PROFInet guidelines, profiles and the PROFInet
Runtime Software are available on www.profibus.com
PROFInet Technology and Application, November 2003
21
PROFInet
System Description
Version November 2003
Order number 4.132
Publisher
PROFIBUS Nutzerorganisation e. V.
Haid-und-Neu-Str. 7
D-76313 Karlsruhe
Germany
Tel. : +49 (0) 721 / 96 58 590
Fax : +49 (0) 721 / 96 58 589
[email protected]
PROFIBUS Trade Organization PTO
16101 N. 82nd Street, Suite 3B
AZ 85260 Scottsdale
USA
Tel. : ++1 480 483 2456
Fax : ++1 480 483 7202
[email protected]
Liability exclusion
PNO / PTO has elaborated the contents of this brochure carefully. Nevertheless, errors can not be excluded. Liability of PNO / PTO is excluded, regardless of its reason. The data in this brochure is checked periodically, however. Necessary corrections will be contained in subsequent versions. We gratefully accept suggestions for improvement.
Terms used in this brochure may be trademarks, their use by third parties for any purposes may violate the rights
of the owner.
This brochure is not a substitute for standards IEC 61158 and IEC 61784 and the PROFIBUS and PROFInet
guidelines, profiles as well as the PROFInet Runtime Software. In case of doubt, please refer to these publications which take precedence.
Copyright by PROFIBUS Nutzerorganisation e.V. 2003. All rights reserved.
22
PROFInet Technology and Application, November 2003
PROFIBUS International
Support Center
Haid-und Neu-Straße 7
D-76131 Karlsruhe
Phone ++49 721 96 58 590
Fax ++49 721 96 58 589
Email: [email protected]
www.profibus.com
© Copyright by PNO 11/03
all rights reserved
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