The road to Wireless – which wireless standard suits you best?

17/08/2015

WiFi, Bluetooth or Zigbee? Tom McKinney of HMS Industrial Networks offers a review of the available short range wireless standards for industrial applications.

Tom McKinney, Business Development Manager at HMS Industrial Networks

Tom McKinney, Business Development Manager at HMS Industrial Networks

Recently the buzz around Industrial IoT has grown to a deafening roar. The market for IIoT devices is projected to grow exponentially over the next several years as businesses start to capture more data regarding their operations. That data will be used to monitor and optimize processes, and as companies learn to use the data they capture to improve processes, the result will be increased productivity. Beyond internal productivity, this data may lead to improved company-to-company operations benefiting both the producer and the customer.

Multiple technology advancements have converged to make large-scale Industrial IIoT deployments possible. These advancements include reduced cost of data storage, lower power RF solutions and higher levels of network accessibility. Another important enabler for Industrial IoT is wireless standardization.

Wireless is nothing new
Wireless networks have been used for over 30 years in the industrial market. In the past, these networks were typically sub 1GHz proprietary systems. The solutions used simple modulation techniques like amplitude-shift keying (ASK) or frequency-shift keying (FSK). Radios that supported these types of modulation could be created easily with a handful of discrete parts. The drawback of these solutions were a complete lack of security and limited bandwidth.

Over the last twenty years, several standards have been developed to define robust radio solutions. The most recent standards are secure enough for broad deployment. In addition, several new free-to-use frequency bands where introduced in the 80s including the 2.4GHz and 5GHz bands. Deploying a standardized radio solution today is a cost-effective secure way to both monitor and control devices in the field or factory. Given the number of wireless standards to choose from, the question becomes which standard is the right standard to deploy.

Summary
1) WiFi
a. Pros
i. Highest Bandwidth up to 600Mbits/s with 802.11n
ii. Fixed 25 MHz or larger Channels
iii. Support for 2.4 and 5GHz channels
iv. Extensive security features
b. Cons
i. Range is lower with higher data rates and 5GHz
ii. Not a good match for battery powered sensors
2) Bluetooth/BLE
a. Pros
i. Very low power
ii. Massive deployed
iii. Very good performance in congested or noisy wireless environments
iv. Ease of use, no frequency planning or site map requirements
b. Cons
i. Max data rate of 2Mbits/s
ii. No automated roaming standard
3) Zigbee
a. Pros
i. Very low power
ii. Fixed channels between WiFi channels in 2.4 GHz band
iii. Support for sub 1GHz bands
b. Cons
i. Complicated mesh network
ii. Max bandwidth of 250Kbits/s

So let´s take a look at the three most common wireless standards deployed in the 2.4GHz band: Bluetooth, WiFi and Zigbee.

WiFi
WiFi or IEEE 802.11a/b/g/n is the widest deployed consumer and enterprise wireless TCP/IP network solution. WiFi is short for Wireless Fidelity and is a standard used to identify Wireless Local Area Network (WLAN) devices. The committee managing this standard is aims to create the best possible wired TCP/IP network replacement. The committee prioritizes security and speed over all other tradeoffs. As a result, 802.11n has the highest bandwidth of any short range wireless standard. The drawback is power consumption and processing power required to effectively manage the 802.11 stack. These drawbacks created a gap in the market and several standards have emerged to address the very low power wireless market.

Bluetooth
Bluetooth and Zigbee were both introduced to address markets not serviced well by WiFi. The Bluetooth standard addressed the needs for a low power Personal Area Network (PAN). A PAN is defined as the network that surrounds a person or a smart device. The requirements include fast association, simple human-to-machine interfaces and low power. In a PAN, multiple transmitters can be placed very close together – Bluetooth includes timing to ensure device transmitters don´t overlap. Bluetooth was also designed under the assumption it would have to co-exist with WiFi and includes a frequency hopping algorithm to ensure Bluetooth messages can get through even when multiple WiFi channels are active. Finally, because Bluetooth uses a very low power transmitter, it is less sensitive to multi-path compared to WiFi. As a result, Bluetooth can be deployed successfully without extensive RF site reviews and planning. The system is very resistant to noise and interference.

Zigbee
Zigbee is based on IEEE 802.15.4 which is a general-purpose, low-power wireless radio standard that allows different protocols to be built on top of the standard radio. Zigbee set out to support low power sensor networks capable of covering a large area. Zigbee uses meshing networking and a very aggressive power profile to meet the needs of this niche market. Zigbee´s protocol is designed for quick turn-on and turn-off, thereby saving power. Several other protocols have been built on top of 802.15.4 including ISA100, WirelessHART and 6LoWPAN.

Bluetooth Low Energy
Bluetooth Low Energy (BLE) was introduced as an update to the Bluetooth standard. Leveraging some of the techniques used in 802.15.4, BLE was able to achieve even lower power points when compared to Zigbee and support many of the features originally created by the Zigbee standards effort.

Selecting the standard for you
So which standard is the right standard to deploy? That depends on the system requirements. In summary, WiFi has the highest bandwidth and most comprehensive stack but Bluetooth, BLE and Zigbee offer features ideal for particular applications. For example, if monitoring battery-powered sensors over a very large area, Zigbee would be the ideal standard. Bluetooth/BLE works well as a cable replacement point-to-point technology or for monitoring sensors over a smaller area. BLE has a huge installed base of tablets and phones making it an excellent choice for human-to-machine interfaces.

Although technology standards may vary, there is no doubt that more and more applications will be wirelessly connected in the near future. With the advent of Industrial IoT, billions of devices will need to hook up to the Internet, and many of these connections will undoubtedly be wireless.


Foundation & Hart to merge?

26/09/2013

It has finally been formally acknowledged. After many years of co-operation Fieldbus Foundation and HART are strongly considering pooling their resources. Where the proposed merger leaves other standards, particularly ProfiBus remains to be seen.

The Fieldbus Foundation and the HART Communication Foundation have entered into discussions on the potential for merging the two organizations into a single industry foundation dedicated to the needs of intelligent device communications in the world of process automation.

fartThe chairmen of the two organizations—Dr. Gunther Kegel of the Fieldbus Foundation and Mr. Mark Schumacher of the HART Communication Foundation—issued the following statement on behalf of their Boards of Directors:

“We believe combining the resources and capabilities of each foundation into a single organization will provide significant benefits to both end users and suppliers. For end users, a single organization that combines the power of both Fieldbus Foundation and HART Communication Foundation would provide a full solution that addresses every conceivable aspect of field communications and intelligent device management for the process industries. For suppliers, a single organization would create efficiencies in resource utilization, consistency of processes and procedures, and would deliver significant improvements in member services and support.”

The Fieldbus Foundation and HART Communication Foundation have worked extensively together in the past and have a long history of cooperation. For example, the two organizations worked together on the development of common international standards such as Electronic Device Description Language (EDDL) and, most recently, the development of the Field Device Integration (FDI) specification. The merger offers significant potential to harmonize many aspects of the two protocols, making it easier for end users and suppliers to implement the technology and obtain the full benefits of each technology in plant operations and maintenance.

In preliminary discussions, the presidents of the two organizations, Richard J. Timoney of the Fieldbus Foundation and Ted Masters of the HART Communication Foundation, added that many synergies already exist and closed by commenting:

“We are both confident that today’s decision to investigate the merger of these two organizations provides momentum for a major step forward in the evolution of intelligent devices and the world of industrial communications.”

More details are given in this Question & Answer paper published with this announcement!

The Fieldbus Foundation and HART Communication Foundation have signed a memorandum of understanding for a possible merger of the two organizations. This proposed merger is still in the exploratory phase and is not yet guaranteed. Here are some answers to frequently asked questions about the merger.

Q: Is the merger a foregone conclusion, with an agreement to merge the two organizations that has been approved by the Boards of Directors?
A: No. What has been agreed is that each organization will appoint a study team to review the possibility of merging the organizations based on an increased value of a single organization, as well as significant benefits to their respective memberships and the automation industry in general.

Q: Would this be a true merger or an acquisition of one organization by another?
A: The merger would be a true merger of equals and not an acquisition of any one organization by another. A combined organization of Fieldbus Foundation and HART technologies could better leverage the complementary benefits of the technologies. The new combined organization would create more cooperation and collaboration. In addition, improved economies of scale would be realized through merging training and education; seminars; testing and registration; participation at trade shows, conferences, and events; online presence; and social media strategies.

Q: I am a member of only one of the Foundations. How would a merger affect my future membership?
A: Membership in either one of the existing foundations would carry over into the new proposed organization with the same rights and benefits that members enjoy today.

Q: If I were a member of both Foundations, how would this affect my membership costs?
A: While we have begun an analysis of our respective memberships, we have not yet defined the membership model as it relates to membership dues. Members of both foundations should see increased efficiencies and reduced total costs as more and more standards, processes and procedures are harmonized. Over time, we anticipate suppliers recognizing more efficiency compared to membership in both organizations.

Q: If the investigation were successful, when would a merger likely happen?
A: There is still a lot of exploratory work to do in regard to due diligence in the financial and legal arenas. Everything we do must meet strict criteria in terms of benefitting our membership and the broader automation market, including our mutual end users. Once that is done, there are board and membership votes and, if successful, legal filings. Our target is to have everything completed by mid-2014.

Q: Who will decide if the merger is to proceed?
A: The decision to proceed with the merger will flow through three steps. First, the study team will prepare a report and recommendation for each board of directors. Once that is completed, the boards will individually vote to proceed or not. Finally, if both boards vote to proceed with the merger, the proposal will go to a member vote in both organizations.

Q: What are some of the goals of the proposed new merged organization?
A: There are a number of goals:

• Collaboration on new and existing technologies.
• Fully integrated marketing strategy to advance the extensive use of digital
devices.
• Improved products and services.
• Increased market share of digital field devices in total device market.

Q: Would the technologies and protocols of both Foundations continue to exist
and evolve on their own?
A: Both the FOUNDATION fieldbus and HART specifications would continue to exist
separately and evolve. Each protocol would retain and maintain its own brand name, trademarks, patents and copyrights. The proposed organization would continue to seek areas of logical harmonization just as we have with EDDL and FDI.

Q: How would the proposed organization deal with the different wireless
strategies that exist?
A: The proposed organization would continue to support the wireless strategies that exist today within each organization.

Q: How would the proposed merger affect the current activities regarding FDI?
A: Both organizations are totally committed to the FDI project and would continue to support FDI as the sole integration technique for smart devices.

Q: Would the two organizations move to a single location?
A: Pending approval of the merger, the plan is to co-locate both organizations into a
single facility as soon as it is practical.

Q: How would the merger affect host system, and device testing and registration?
A: Both the Fieldbus Foundation and HART Communication Foundation are currently working on common device and host testing procedures under the FDI Cooperation initiative. That is one of the major benefits of the FDI project. Although elements of those tests may differ based on the structure of the protocols, there are many elements that the two organizations share in common. We anticipate that we will move toward a common set of procedures for both device and host testing, and a common registration process.


PROFINET – broadly positioned

22/11/2012

Discussion on PROFINET in the context of Process Automation

Dr. Peter Wenzel, PI (PROFIBUS & PROFINET International)

Market penetration of PROFINET

The move to Ethernet-based communication systems is in full swing. This is true especially for PROFINET as proven by the latest figures on installed PROFINET devices. With 1.3 million new PROFINET devices sold on the market in 2011, the total installed base has now risen to 4.3 million devices. Factory automation projects account for almost all of these figures. It is the goal of PROFIBUS & PROFINET International (PI) to make PROFINET up the task for the full range of industrial automation applications.

In order to optimize PROFINET for the wide range of requirements of factory and process automation applications, the new PROFINET V2.3 version has been supplemented in two respects. First, advanced functions for integration and parameter assignment of devices (for Configuration in Run), scalable redundancy, and time stamping (for determining Sequences of Events) have been added that open up the market for PROFINET to process automation applications. Second, a performance upgrade has been implemented with the addition of the Fast Forwarding, Dynamic Frame Packing, and Fragmentation functions that extends the market for PROFINET all the way to high-end motion control applications, while still ensuring its coexistence of with IT applications.

Innovation of PROFINET for process automation

Innovations of PROFINET

In its quest to make PROFINET fit for use in process automation, PI collaborated with users to develop a set of requirements. In addition to user-friendly operation, protection of investment for the end user is an essential requirement because instrumentation in a process control system typically has a life cycle of several decades. This ensures that plant owners using PROFIBUS today can rely on a future-proof system and can change to PROFINET at any time.

The requirements that apply to PROFINET for process automation mainly include the functions for cyclic and acyclic data exchange, integration of fieldbuses, integration and parameter assignment of devices (Configuration in Run), diagnostics and maintenance, redundancy, and time stamping (Sequence of Events).

Fieldbus integration in PROFINET

For two-wire conductor systems used both in standard applications and in applications involving energy-limited bus feed of devices in hazardous areas, PI is continuing to rely on its thoroughly proven PROFIBUS PA solution. The question then arises as to the optimal gateway from PROFIBUS PA to PROFINET. A proxy concept for the integration of fieldbuses in PROFINET, which was specified several years ago, is available for this. This concept can be used to integrate the three communication systems used in the process industry, namely PROFIBUS PA, HART, and Foundation Fieldbus. It is based on standardized mechanisms for mapping the fieldbus-specific properties onto PROFINET. The bus systems are integrated using gateways (proxies) that link the higher-level PROFINET network to the fieldbus system to be integrated. The proxy becomes responsible for implementing the physics and protocol and ensures the exchange of all I/O and diagnostic data as well as alarms with the field devices.

The availability of automation systems is of critical importance in continuous processes in particular because, for reasons that are known, plant operation often must not be interrupted under any circumstances. To avoid automation failures caused by wire breaks, short circuits, and the like in these types of plants, a scalable redundancy concept was developed for PROFINET, in which the redundancy solution can be structured optimally to meet the specific requirements of the application.

Some applications require a time stamp for digital and analog measured values and alarms that is accurate to the millisecond. A precondition for this is an exact time synchronisation of the components involved. The purpose of this is to ensure that I/O devices can provide real-time information about alarms and other important events with a time stamp that is based on a network-wide standardized time of day. The time recording of events is the basis for determining the Sequence of Events, thereby enabling an exact description and analysis of a possible error case, for example.

Like redundancy, uninterrupted plant operation – including when reconfiguring devices and networks and when inserting, removing, or replacing devices or individual modules while the plant is operating – plays an important role (Configuration in Run). The actions are performed in PROFINET without causing any interruption or adversely affecting network communication. This ensures that plant repairs, modifications, or expansions can be performed without a plant shutdown in continuous production processes, as well.

Fieldbus and Ethernet systems provide extensive possibilities for diagnostics, e.g., for maintenance. These include, for example, the provision and transmission of identification and maintenance (I&M) data, as is familiar from PROFIBUS and PROFINET applications, or the communication of events and transmission of device status according to NAMUR Recommendation 107. Manual changes made directly on the device or via external parameter assignment tools are signaled to the control system via PROFINET as parameter change events. This allows the control system to detect deviations from the central data management, notify the user, and perform updates, if necessary.

Performance upgrade for machine building
With the latest PROFINET V2.3 specification, a performance upgrade is available to users. This was made possible by the incorporation of intelligent functions in the new version of the specification, namely Dynamic Frame Packing, Fast Forwarding, and Fragmentation.

Functionality of Dynamic Frame Packing

PROFINET real-time communication (RT) uses the prioritization methods of Ethernet and can therefore be implemented on standard Ethernet controllers. The accuracy of the firmware implementation determines the jitter of the transmitter clock, just like on other Ethernet systems. With a data rate of 100 Mbps and full-duplex transmission, bus update times that are faster by several factors compared to today’s fieldbuses are possible. As a result, RT is usually fully sufficient for typical factory automation applications. For applications whose requirements include the need to synchronize nodes to within 100 µs or less or to form a highly dynamic control loop via the bus, additional measures become necessary. The highly accurate isochronous real-time (IRT) synchronization process of PROFINET eliminates Ethernet transmission delay times of differing and fluctuating lengths.

PROFINET enables parallel TCP/IP communication for standard data, diagnostics, or parameter assignment purposes alongside both RT and IRT communication, without the need for additional modules or firmware measures. This is made possible by a free time slot in the update cycle. Data access, diagnostics, and parameter assignment are the same with RT and IRT communication. The user only has to specify when configuring whether RT or IRT communication will be used.

PROFINET V2.2 meets the real-time requirements of more than 95% of applications. Only applications involving specific configurations in which many nodes with few bytes are connected in a line topology may have more stringent performance requirements. For example, the possible bandwidth utilization is not optimal when padding is used, i.e., filling of frames to the minimum 64 byte length in compliance with standards. Additional measures have been taken in the PROFINET V2.3 specification for this case. These measures at different starting points produce high-performance communication with exact deterministic behavior at update rates as fast as 31.25 μs, without affecting the openness for TCP/IP communication.

The decision whether to forward a frame in the integrated switch of a device requires address information in the frame header. With Fast Forwarding, the FrameID (FID) address information is integrated once at the start of the frame header so that instead of having to wait for a large number of bytes it is possible for forwarding to take place early on. As a result, the current standard delay times of 3-6 µs per node can be reduced to 1.2 µs.

To optimise the ratio of frame to user data, the Dynamic Frame Packing function was defined. For this, improvements were made to the summation frame method already used in several fieldbuses in which the I/O data for several nodes on the network are integrated in one frame, thus requiring only one frame header and trailer (FCS). In contrast to ring bus systems, PROFINET uses the full-duplex principle of data transmission common in Ethernet systems. Here, input and output data are sent simultaneously on the 2-pair cable. When a single summation frame is used, this complete frame is sent, received, and checked all the way to the last node, including the checksums. With Dynamic Frame Packing, the data of the first nodes in the line, which are not relevant for the nodes placed further at the end, are removed during the passage. As a result the frame becomes shorter when passing through each node.

Time scheduling ensures the unlimited openness of PROFINET for TCP/IP frame transmission alongside IRT communication. Specifically, it ensures that the network is reserved for TCP/IP frames rather than user data during a defined time phase. With Fast Ethernet, the transmission of one TCP/IP frame can take up to 125 μs, which defines the minimum cycle time. The Fragmentation function defined in PROFINET V2.3 takes large TCP/IP frames in the individual nodes and, if necessary, divides them into smaller individual parts prior to sending. These fragments are then sent in consecutive cycles. The counterpart then reassembles the fragments into a complete TCP/IP frame. In this way, it is possible to configure bus cycles of 31.25 μs with shared user data and TCP/IP communication.

Summary
With Version V2.3, PROFINET now meets all requirements for automation applications, ranging from process automation and factory automation to high-performance motion control applications. This technology development paves the way for developing cost-optimized automation solutions and is especially important for meeting the demand for investment protection, both for existing plants and expansions to existing plants. PROFIBUS and PROFINET are not competing solutions but rather are complementary solutions. While PROFIBUS is used in continuous processes and hazardous areas, PROFINET is primarily of interest in applications requiring integration all the way to the corporate management level or whose real-time communication requirements cannot be met by conventional fieldbuses.


The bar is set!

22/10/2012
PROFINET’s remarkable achievement of 31.25 µs cycle time and how this impacts on the future of data transmission:

What are the factors for successful automation?
Factors like speed or the excellent performance capability of a particular sensor are often mentioned. Nevertheless, the outstanding features of an individual component can only be taken advantage of if the design of the overall system is compatible. In practical terms, this means that high-precision sensors are of little use without a fast synchronous network, and vice versa.

The Chairman speaks!

Karsten Schneider

For many users, a cycle time of 31,25 µs is almost unimaginable. Karsten Schneider, PI Chairman, explains the tools used to demonstrate this fast cycle time and the significance it has for real-world applications:
Read-out: Mr. Schneider, just how fast is a cycle time of 31.25 µs?
K.S: In fact, it is difficult to grasp just how fast this cycle time is, which is why we constructed a live model. Because LEDs react too slowly, we used an oscilloscope to visualize the cycle time of 31.25 µs as well as the slight jitter over the entire system. In addition, an analog signal was sampled, transmitted via PROFINET, and output at another station in our model.
Read-out: Which applications will benefit of this cycle?
K.S: It is of interest to highly dynamic measuring equipment applica-tions, since sampling rates up to 32 kHz over the network are possible. It could be used, for example, to record torque characteristics in test stands.
Read-out: Why will isochronous operation play an even more important role in the future?
K.S: The processes of the future will have to be tuned to each another with even greater precision. A typical example is the multi-axis closed-loop control process in printing machines. A more precise isochronous operation will not only increase the productivity of the overall printing machine but will also allow production of printed products with higher-resolution and thus sharper images. Another industry sector with stringent requirements for isochronous operation is the packaging industry. While the material filling process runs relatively slowly, the primary packaging process requires a very high speed. Both processes must be precisely tuned to each another to avoid disruptions in the overall process.
Read-out: And how have you demonstrated this feature with the model?
K.S: Isochronous operation was demonstrated with a traditional stroboscope test. For this, we aimed a stroboscope at a variable-speed disk in such a way that a permanent image of a written text is produced.
Read-out: Your are always emphasizing openness as a highlight of PROFINET. Does this also apply to the short cycle time of 31.25 µs?
K.S: We have placed a high value on this during development. Even with the short cycle time, standard data can be transmitted without limitation via TCP/IP. We have a full HD video taken in our test setup that demonstrates undisturbed transmission of these data all the way through the PROFINET system. The ability to transmit standard data is necessary in order, for example, to transfer new parameters, quality assurance data, or images for production monitoring. An example of this is the transmission of data from high bay storage systems via a camera. In addition, there is a trend in assembly lines toward recording and storing torque characteristics of screws for quality control purposes. These data can also be transmitted without any problems.

Whenever performance is discussed, the overall system often takes a back seat. The result: the overall speed of the system is only as fast as the slowest link. In other words, you may have fast communication, but it is of little use if your controller or I/O system do not have compatible cycle times. One must always bear in mind that the terminal-terminal response time depends heavily on the bus update time. The critical factors are therefore the overall system accuracy as well as the synchronization of controller, communication, and inputs/outputs. The basis for achieving such a high-performance overall system is the use of a fast synchronous network.This is just one of the reasons for the unbridled popularity of the PROFINET technology. The communication system, which reflects all facet of automation, is enjoying success across all industry sectors throughout the factory automation, motion control, and process automation markets. Regardless of the industry sector, it is not just the system’s speed that is playing a critical role but also its real-world diagnostics, integration, safety, and wireless solutions. In 2011, for example, 1.3 million new PROFINET devices were sold on the market, bringing the total installed base to 4.3 million devices.

In automation, the challenge lies in not knowing what the future holds in terms of requirements. For example, an end user may be completely satisfied at the moment with its automation and communication systems. But what happens 5 years later when that user’s Quality Assurance Department requires certain production procedures to be transmitted over the communication system in realtime?

In order to be equipped for future tasks, PROFINET Specification V2.3 defined mechanisms that will further speed up communication with PROFINET. An important step of this definition is the performance upgrade of PROFINET to achieve cycle times of 31.25 µs. This upgrade is for applications that have more stringent demands on communication while also requiring isochronous operation. The key thing here is that the system remains scalable. Regardless of which level of performance will be required in the future, the user can rely on a single communication system without system gaps.

Faster to the goal
Three mechanisms make this possible: Fast Forwarding, Dynamic Frame Packing, and Fragmentation. As a result, short cycle times of as little as 31,25 µs can be achieved together with high-precision isochronous operation. To maintain compatibility with the previous specification, three main tricks have been used. To optimize the IO bandwidth, the transmission time of messages was shortened from 6.3 µs to 1.2 µs by forcing an earlier forwarding decision (Fast Forwarding) during switching. Previously, a standard Profinet frame could only be forwarded in the switch when the complete Ethernet header was received.

Like other communication systems, PROFINET uses the summation frame method for optimizing the ratio of frame to user data, thereby opening up further potential for optimization. In contrast to ring bus systems, PROFINET relies on the performance advantages of a full duplex system, i.e., input and output data are sent simultaneously on the 2-pair cable. When a single summation frame is used, this would have to be sent, received, and checked completely down to the last node, including the checksums. This is where Dynamic Frame Packing comes in. Because the data of the first nodes in the line are not relevant for the nodes placed further at the end, these are removed during the passage. This shorts the frame in its passage through the network. The time-determining arrival of the frame at the last node is thus much sooner, thereby significantly reducing the overall update time for all nodes.

A proven and important advantage of PROFINET is its unlimited TCP/IP communication even when isochronous realtime communication is occurring simultaneously. For this, the architecture of PROFINET provides for time scheduling in addition to synchronization. The network is not loaded with I/O frames during a defined time phase but instead is free for any TCP/IP frames, which can take up a duration of up to 125 µs with Fast Ethernet and thus define the minimum cycle time.
Next, the fragmentation defined with PROFINET V2.3 takes large TCP/IP frames in the individual nodes and, prior to sending, divides them into smaller fragments, which are sent in consecutive cycles. The counterpart then re-assembles them so that the upper-level application layer receives an unaltered TCP/IP frame. This allows users to realize bus cycles of 31.25 µs with shared I/O and TCP/IP communication, without having to reduce the available bandwidth for the TCP/IP communication.

Outlook
Applications exist today that can benefit from a cycle time of 31,25 µs, such as high-speed closed-loop motion control applications and applications in the measuring equipment sector.

A key aspect for the user is the compatible expansion options that allow it to update an individual controller or field device and still retain existing functions. Only when the user wants to make use of the new functions, e.g., for performance optimization, is it necessary to fully update controllers and field devices to the latest version. The user protects its investment, while remaining free to access the reserved performance at any time.

The resulting new generation of PROFINET modules will implement all these new functions in hardware. Accordingly, various technology suppliers will offer easy-to-integrate solutions in the form of ASICs, network controllers, or FPGAs and thus provide device manufacturers with the basis for producing high-performance solutions that meet customer requirements. As a result, users can rely on a coherent approach that uses both a fast, high-performance network as well as fast devices. A system designed with both in mind is essential for realizing the benefits of increased performance in practice – today and in future applications.


#SPS 2012: Successful if not quite hitting secure note!

01/12/2011

“Arriving at #SPS/IPC/DRIVES. Looking forward to a great show”

Busy entrance area! (IE Book)

This was one of the first tweets we saw on this, possibly the biggest automation exhibition in the world this year. The SPS/IPC/Drives show is held annually in the Northern Bavarian city of Nuremberg. This year the dates were the 27 to 29th of November, As last year we were unable to make it this time, however there were some excellent reports which we have used (and linked to) in compiling this brief impression.

As might be expected the automation industry presented its capabilities in full force at the exhibition. There was a record number of 1.429 exhibitors which attracted more visitors than in the past, as 56.321 trade visitors filled the 12 halls to gather information about the latest products and solutions in electric automation. Well may it be said that SPS IPC Drives 2011 set a clearly positive sign for the future despite the gale-force winds blowing in financial circles for the last three years.

The conference which took place in parallel to the exhibition also recorded an increase this year with an attendance of 349 delegates. For three days the conference provided a platform for intensive discussions between product developers, suppliers and users. The opportunities for users to exchange information and knowledge were at the heart of the newly introduced user sessions.

Attendance: 2011 (2010)
Exhibitors: 1,429 (1,323)
Visitors: 56,321 (52.028)
Conference delegates: 349 (302))

Like a lot of European events there was not a small number of tweets from various sources and in various languages, but those that did tweet helped form an impression of how things were. One of the most prolific of these was Leo Ploner of the IE Book who gave us a sort of running commentary on his day interspersed with twitpics of stands and products which impressed him. This comprehensive collection of pictures have been added to the IE Book Facebook Page and we recommend that you pay a visit and see who you know and what products impressed him. “#SPS/IPC/Drives very busy on the first day of the show. Big crowds at all the stand” he reported after day one.

Put on those cans!
Also present on the first day was Control’s Walt Boyes, who gave up his Thanksgiving to be in Europe for the show. This is an interesting account in that it gives an American take on how things are done in Europe, simultaneous translations and the non-English keyboards (Now he knows how Europeans might feel in the U.S!)

Gary Mintchel of Automation World also found himself in Nuremberg during this week. His blog, Feed Forward,  provides us with “a roundup of various announcements that I gathered during my sprint around the halls and press conferences.” He managed to squeeze in a visit to the Siemens plant in Amberg on the day before the show opened!

The Control Engineering Europe team attended the show in force, collecting a great deal of feature ideas, as well as details about some of the most innovative launches at the show. They promise that further details of the most exciting product launches from the event will be presented in the February issue of the magazine.

ARC Reports
ARC Advisory also discuss day one in an article by Florian Gueldnerwhich looks at the Automation Outlook for 2012.  He bases this report on that of the ZVEI, as well as companies interviewed at the event. Their David Humphrey reports on The big trends in a further report on day two.

A busy corner at the show!

Come hither!
Of course exhibitors tweeted on their own stands and new products. Heading the posse was Siemens, who were on their home ground and virtually occupied one complete hall (There were twelve halls in all!). They mounted an impressive press conference on the first day. Their “big” announcement was the naming of their full motor range, now called “Simotics”. They also introduced some extensions to their TIA (Totally Integrated Automation) portal. Jochun Koch’s blog features some video presentations with English voice-over – Automation and IT (their Scalance range) – take a look and remember to click for the English translation if needed!

Phoenix Contact have a video tour of their stand – as it was being set-up – which they entitle “Solutions for the future – Phoenix Contact.” There are in fact a number of other videos from Phoenix Contact on theie YouTube site. Their final tweet from the show as they rolled up the tent was, “What innovation! More than 3,000 visitors @ Phoenix Contact.”

The Pilz Stand!

Also using video to press their message is Beckhoff who have produced reports for each day. This is Day One.  They exhibited their complete range of PC- and EtherCAT-based control technology and a large number of new products in all technological areas (IPC, I/O, Automation and Motion). The focus was on their new generation of controllers from the CX2000 series, the new proprietary-developed AM8000 servomotors and the release of the TwinCAT 3 software.

News of PROFINET and PROFIBUS at SPS/IPC/Drives is trickling out  said Carl Henning of his ProfiBlog reports.

Suzanne Gill of Control Engineering Europe reports here on some of the latest innovations that were introduced, which evidenced consumer technology moving into the industrial space and multi product combinations continuing to gain momentum.

We give some more releases from exhibitors on our Conf/Exhibitors pages.

Eric & Joann Byres at the show!

No security!
Another American braving the Bavarian winter was Eric Byres of Byres Technology, recently acquired by Belden (see our article Major acquisition strengthens war on Stuxnet and other malware Sept20’11). It is I suppose unusual that a supplier reports on an exhibition so his viewpoint is welcome. Obviously he has a certain slant on things viewing the exhibits from the security standpoint. He advises that SCADA Security Solutions were scarce at show. “What concerned me was the lack of booth space dedicated to security of any type. Of the 1,429 exhibitors, only 16 reported supplying ‘Industrial security’ technologies or services according to the show guide. This is a hopelessly small number.” He was proud to report however that their “Tofino Security technology accounted for nearly 25% of that total!” More alarmingly he reports that many vendors stated that security wasn’t a concern for them, while users were very concerned and indeed did not quite know what to do about it! Not a pretty picture! He concludes “If the automation world is going to adopt industrial Ethernet with such enthusiasm (which I support), it might want to consider securing it too!”

We referred to the excellent tweeting by Leo Ploner of the IE Book earlier and his very comprehensive report Industrial networking still looking good  tells in great detail what he saw as he moved through the halls. We’ve referred to their pictures above and here is a video which he took of an exhibit at the Sercos Stand.

Re-inventing the electric guitar

Equipped with an MLP industrial control from Bosch Rexroth, the robot guitar can read and play MIDI files. Bus terminals from Phoenix Contact are used to actuate lifting solenoids. Six to pluck the strings and 24 to operate the finger board. The automation bus from Sercos ensures the optimum operation of all components.

One final tweet from KUHNKE Automation sums up one impression “SPS/IPC/DRIVES was a complete success for us! Thank you for coming and the great constructive high-level talks!”

Next year’s automation filled show is scheduled for  Nov. 27. – 29 2012. Will you be there?


 Releases received at the Read-out Offices!

#SPS11: Cybersecurity, certification, safety & other highlights from Wind River – Wind River made several exciting announcements at this year’s faire. On day one of the event, they announced a strategic partnership with ISaGRAF, headquartered in Canada and part of the Rockwell Automation Company, a global leading automation software partner. Together, Wind … Continue reading →

#SPS11 Test drive industry’s first virtual target for software development on SoC FPGAs – Altera Corporation demonstrated its latest industrial embedded solutions for energy-efficient and safety-integrated drive systems. They highlighted how its Cyclone® series of FPGAs enables integrated, high-performance industrial systems such as drive systems with a high-performance control loop in floating point. Visitors … Continue reading →

#SPS11: Industrial Networking and Motor Control Systems from Xilinx – New capabilities for boosting design productivity and using Spartan-6 FPGAs for better system performance and lower bill-of-materials Xilinx announced new Ethernet protocol support and motor control building blocks for its Industrial Targeted Design Platforms, including new EtherCAT, Ethernet POWERLINK, PROFINET … Continue reading →

#SPS11: Hydrostatic actuation desifn concept from Moog – Reliable hybrid technology used in a new energy-saving solution for a variety of industrial applications Moog Industrial Group featured a prototype for a new Electro Hydrostatic Actuator (EHA). Combining hydraulic and electric technology in a self-contained system, Moog’s innovative EHA … Continue reading →

#SPS11: Minicarrier board! – congatec AG presented the conga-QMCB, a new mini carrier baseboard for space-critical applications based on the Qseven standard. The baseboard is ideal for fast prototype design and compact, mobile applications. Measuring just 145×95 mm, the easy-to-integrate mini carrier board is … Continue reading →

#SPS11: TE Connectivity solutions – TE Connectivity showcases its Hybrid Connectivity Solutions Both the Power4Net and the Motorman hybrid connectors integrate several functions into a single compactly designed connector. The flexible Power4Net hybrid connector has space for up to eight power and four Ethernet contacts … Continue reading →

#SPS11: Siemens extends TIA and unveils Simotics as full motor range – Siemens showcased the latest extension to its TIA (Totally Integrated Automation) Portal and unveiled the new name of its full motor range which will be called “Simotics” from now on. In advancing its automation and drives portfolio, Siemens is placing … Continue reading →

#SPS11 Dynamic reporting in process or energy management – COPA-DATA is to present their zenon Analyzer to the public for the first time COPA-DATA will present its new product for dynamic reporting, the zenon Analyzer, for the first time at the SPS/IPC/DRIVES 2011 trade fair. The software is designed … Continue reading →

#SPS11 Green automation initiative

Industrial communication technology facilitates plant-wide energy management within automation systems. HMS Industrial Networks presented a number of solutions targeting energy management in automation systems. Recent research from the AIDA group of German automobile manufacturers (Audi, BMW, Daimler, Porsche, VW) and … Continue reading →


Energy savings potential for production plants

14/07/2011

Prof. Dr. Frithjof Klasen presents the results of a PROFIenergy study

Energy-efficient production means more than just the use of variable-speed drives and efficient motors with low energy consumption. The question going forward is how to selectively place complete production lines or portions thereof into an energy saving mode during unproductive times.

PROFIenergy
The high cost of energy and compliance with legal obligations are compelling industry to engage in energy conservation. Recent trends toward the use of efficient drives and optimized production processes have been accompanied by significant energy savings. One area that has received too little attention in this regard is the handling of production idle times. During idle times in plants and production units today, it is common for numerous energy consuming loads to continue running. It was exactly this problem that a group of automobile manufacturers asked PI to address by defining an energy savings profile using PROFINET infrastructure and communication. The result was the specification of the vendor-neutral PROFIenergy energy savings profile.
PROFIenergy enables an active and effective energy management. During idle times in plants and production units today, it is common for numerous energy consuming loads to continue running. By purposefully switching off unneeded consumers and/or adapting parameters such as clock rates to the production rate, energy demand and, thus, energy costs can be drastically reduced. In doing so, the power consumption of automation components such as robots and laser cutting machines or other subsystems used in production industries is controlled using PROFIenergy commands. PROFINET nodes in which PROFIenergy functionality is implemented can use the commands to react flexibly to idle times. In this way, individual devices or unneeded portions of a machine can be shut down during short pauses, while a whole plant can be shut down in an orderly manner during long pauses. In addition, PROFIenergy can help optimize a plant’s production on the basis of its energy consumption.

It has long been a matter of course in every notebook computer that the hard drive, screen, or notebook as a whole will be placed in standby mode, depending on the operating situation. This function is a device feature and only requires parameter assignment. This is exactly the approach taken in the PROFIenergy concept, in which standardized control commands are used to place devices and machines into energy saving mode via PROFINET.

The initial situation

In 2009 the PI (PROFIBUS & PROFINET International) began work on developing the basic technology of PROFIenergy – the communication profile for operating energy-efficient production plants.

The specification was finished in record time, and the first PROFIenergy devices reached the market in 2010. Since then companies have indicated a strong demand for PROFIenergy products.

PROFIenergy enables use of smart energy management over existing network infrastructures in production. However, the actual energy savings that can be achieved depends primarily on how equipment manufacturers and operators implement the opportunities provided by the technology into their equipment and operating concepts. This requires knowledge of the technical and economical tradeoffs between energy consumption and equipment operating modes.

Since up to now only limited empirical data and hardly any actual data have been available on the relationship between energy consumption and equipment operating modes, a detailed measurement study was needed to provide actual quantitative data and analyses that would support the now-familiar qualitative assertions. The Institute for Automation & Industrial IT (GoogleTranslated!), Cologne University of Applied Sciences, was commissioned to perform this study. The institute is a member of the PI Working Group that developed the PROFIenergy specification and also serves as a PROFINET Competence Center, among other things. It specializes in PROFINET diagnostics and in performing energy consumption measurements and analyses for production plants.

The Study

The goal of the PROFIenergy study is to show the user benefits that will result from using PROFIenergy. These include both the direct benefits associated with improved energy efficiency (electric, pneumatic, thermal energy) as well as the indirect benefits, e.g., resulting from extended service life of operating equipment.

The main tasks of the study include:

  • Performing measurements for recording typical load curves
  • Analyzing load curves
  • Determining the relevance of idle times for energy savings
  • Identifying the potential savings from use of PROFIenergy

To achieve representative results, the study included applications and industry sectors in which PROFINET is used and benefits from PROFIenergy are particularly relevant.

Typical measuring setup of PROFIenergy study in a production plant

The task

Initial analyses and measurements for the PROFIenergy study have been completed on production lines in Germany at Daimler’s Sindelfingen plant and at Volkswagen Commercial Vehicles in Hanover (Panamera production). The behavior of the overall plants and their components were analyzed with respect to load curve, load distribution, and pauses. In addition, the influence of operating modes on energy consumption was analyzed, and pauses were analyzed with respect to frequency and duration.

The measurement concept

Typical arrangement of current transformers flexible current transducers for high power ratings (background); split-core current transformers for lower power ratings (foreground)

The measurements conducted in October 2010 involved long-term recordings on production equipment in order to capture both planned pauses and idle times as well as unplanned pauses and to determine their relevance. The power measurements were taken at up to 15 different measuring points within a plant. As a result, it was possible to record typical load curves and determine characteristic values at different levels, ranging from the main incoming supply down to individual consumers.

Line-side analyzers capable of simultaneous measurement and recording of values were used to measure the power and all characteristic values of the supply system, including voltage, harmonics, and phase offsets. Up to 15 measuring devices were used in parallel for the long-term recordings. Continuous recordings of voltage, current, and power parameters were made over a 7-day period at 1 second measurement intervals. At the same time, synchronous data on equipment status and operating mode were acquired from PLC log data. The synchronization of the measuring devices and the PLC ensured that the measured values at the individual measuring points could be attributed explicitly for subsequent analysis.

Example of the recording of operating mode (PLC signal, top) and load curve (bottom) for a robot system in a production plant

Based on these measurements it was possible to perform a detailed analysis of operating modes and the related energy consumption of plant units. This analysis covered the following points:

  • Typical energy consumption of individual plant units
  • Typical reduction of energy consumption during idle times
  • Characteristic duration of idle times
  • Relevance of pauses (planned, unplanned, operational, model-related)
  • Relevance of plant concept (effect on energy savings potential)

Typical arrangement of measuring points in a production plant

Results

The load curves in the analyzed production plants typically exhibit regularly recurring load profiles that are the direct result of the discrete production steps occurring in production plants. Yet, not all production equipment is active at every point in time. The load curves therefore have typical profiles that are the result of chronological overlapping of individual devices and plant components. However, due to material stores in the infeed or between plant units, there are often no rigid process sequences. The load profiles can thus vary – particularly during the transition to a temporary equipment standstill, in which not all plant components are necessarily affected at the same time (due to run-on, idling of certain stations, additional filling of intermediate stores, etc.).

A noticeable feature of the load curves in the analyzed production plants is the high load peaks, which can be seen in the example measurement results in below, which were obtained over 24 hours in a typical plant segment. While the load level during operation is around 80 kW, the base load is only around 17 kW. At first glance, this does not seem particularly relevant to the search for potential savings by reducing energy consumption during idle times. After all, the base load appears to be less than 20% of the upper load level – a misinterpretation that is easy to make. Here, however, one must not allow the high peak load to conceal the fact that the actual consumption value (that is, what is actually paid for) is the mean value of the load profile, which in this example is around 32 kW.  The base load during a standstill is thus more than 50% of the energy consumption during productive operation and provides significant opportunity for savings if handled appropriately.

In addition to this relative evaluation, attention must also be paid to the order of magnitude of the energy consumption range.

If one compares the energy consumption of the plant segment chosen in this example to the typical energy consumption figures of a private household, the order of magnitude is quickly apparent: the base load measured during a standstill is equivalent to the average energy consumption of approximately 50 households (based on 350 watts/household).

Load distribution and energy flow within the plants

An important aspect of the study was the analysis of the load distribution within the different plants. Due to the structured distribution of the measuring points – extending from the incoming supply to the terminal level – it was possible to analyze the energy consumers separately and to identify their typical characteristics during production and idle times

Power distribution and energy flow using a Sankey diagram

Robot systems are a prominent feature in automotive production. A large proportion of the energy consumed, i.e., on the order of 30 to 60 percent, is typically used for operating the robots (Figure xx). Robot systems are also predominant energy consumers during idle times. A robot typically consumes up to 300 watts during idle times.

On the other hand, controllers typically account for 2-3% of the overall energy demand.

Analysis of idle times

Idle times occur for different reasons (planned, unplanned, operational, model-related) and provide important clues to the operating behavior of a plant. Brief standstills are often an indicator of opportunities for optimization with respect to equipment synchronization and/or the material store; longer standstills occur during planned pauses and planned shutdowns and when problems occur.

Based on the results of the study, not only planned but also unplanned idle times are relevant for the use of PROFIenergy. Special attention was therefore given to analyzing the duration of the idle period. The idle times were classified according to their duration, and the cumulative duration of all the individual events was calculated (total time of all standstills occurring in one class) to produce the analysis of idle times shown in Figure xx.

Idle times of short duration occur relatively frequently, but are typically not candidates for switchover to energy saving mode because of the time required to restart the equipment from standby mode.

Based on previous estimations, it can be assumed that for many plant components, a transition to energy saving modes is appropriate for idle times lasting 5 minutes or more. If this approach is taken, one can conclude for the plant example in Figure 7 that 64% of the cumulative idle times last more than 5 minutes and thus offer significant potential for the use of PROFIenergy.

An even more pronounced result can be seen in the curve for another plant example in Figure 8 in which the relevant portion of the exploitable idle times accounts for 90% of the cumulative idle times.

Figure 7

Figure 8

The potential for energy and cost savings

Most of today’s production plants have only a ‘hard switch’ on/off option.

Experience dictates that problems will occur when restarting switched-off equipment. Out of fear of startup problems, operators often do not switch off production equipment even during extended standstills, e.g., overnight and on weekends. These planned idle times account for a significant portion of the operating hours, depending on the shift model. Unplanned idle times contribute even further to this. Based on the results of the study, it can be assumed for typical automotive production plants engaged in body construction and assembly that a production plant with 2-shift operation will consume about half (47%) of its total energy consumption during idle times. Only 53% of the energy consumption is used for productive operation.

As a result, the use of PROFIenergy offers significant potential for savings. It must be noted, however, that all of the energy consumed during idle times cannot be saved. For one thing, the PROFIenergy concept does not switch-off equipment completely but rather places it in an energy-saving mode; this mode can differ depending on the equipment component. In addition, it only makes use of idle times of sufficient duration.

PROFIenergy applications
PROFIenergy differentiates the following four main applications
Application 1: Energy savings during brief standstills
Examples of brief standstills are breakfast and lunch breaks. The standstills range from a few minutes to an hour. For these brief standstills, energy can be saved by placing unneeded consumers in energy saving modes. The energy savings are not as high in this application as in application 2, in order to allow a fast restart.
Application 2: Energy savings during extended standstills
Nights and weekends are typical examples of these idle times. The duration of the standstill is significantly longer so that more consumers can typically be switched to more stringent energy saving modes, thus maximizing the possible energy savings.
Application 3: Energy savings during unplanned standstills
Because in this case the duration of the standstill cannot be predicted, it is first classified as application 1, i.e., a limited number of consumers are placed in energy-saving modes, to avoid interfering with a fast switchover to production. If the standstill turns out to last longer, a switch can be made to application 2 in order to achieve greater energy savings.
Application 4: Measurement and representation of power consumption
PROFIenergy allows acquisition and representation of consumption data of devices during operation. These consumption values can be visualized on an HMI device, for example.

Based on the previous results, it can be assumed that the use of PROFIenergy can save approximately 70% of the energy during exploitable idle times. The result is a savings of 33% of the total energy consumption of a plant.

In summary:

• Half of the total energy consumption occurs during idle times

• One-third of the total energy consumption can be saved by using PROFIenergy

Based on the energy consumption of a typical production line of 210,000 kWh per year, this yields a potential savings on the order of 7,000 € per year (based on 0.10 € per kWh).

The new opportunities made possible by PROFIenergy will change how plants are operated, assuming that these opportunities are considered during plant engineering, i.e., during development of plants and plant concepts.

PROFIenergy is both the basis for and the driver behind this development work.

The prerequisites

To fully exploit the savings potential, the use of PROFIenergy-capable control components alone is not enough. In addition, changes to plant concepts are needed to enable devices or plant units to be placed selectively in energy-saving modes. In so doing, there must not be any impairment of safety-related functions in standby mode for safety-related applications.

For machine and plant manufacturers, this opens up new opportunities for gaining a competitive advantage. But this will only be the case, if purchase decisions for new equipment take into account energy consumption costs in addition to investment costs. Plant owners must clearly define their requirements to plant manufacturers so that PROFIenergy can be included in the design plans for equipment from the outset.

Summary

The current results of the PROFIenergy study confirm significant potential energy savings during pauses and idle periods of up to 50% or more and a savings potential on the order of 33% of the total energy demand. In addition to planned pauses, e.g., on the weekend, unplanned idle periods of a plant represent another significant potential candidate for use of PROFIenergy.

To optimize these potential savings, however, corresponding plant concepts are required, for example, to allow plant units to be selectively placed in energy-saving mode and, if necessary, to be switched off selectively.


Open to new ways!

01/04/2011

New prospects with PROFINET for the process industry

by Dr. Peter Wenzel, PI (PROFIBUS & PROFINET International) Support Center

With over three million installed nodes, PROFINET has long since become a familiar feature of production automation and drive engineering applications. But what about the process automation sector? Although this sector traditionally reacts cautiously to new technologies, users have expressed heightened interest in PROFINET.

Food and beverage industry sector

In particular, the food and beverage industry sector is interested in PROFINET because of its large number of upstream and downstream processes. The chemical, oil and gas, and pharmaceutical industries have recently expressed considerable interest in the technology, as well. PROFIBUS PA is already widely used by facilities in these industry sectors. However, an integrated communication system such as PROFINET is essential to enable complete integration of centralized process-related operations of a plant with downstream applications involving mostly discrete processes, such as filling and packaging.

For this reason, PI (PROFIBUS & PROFINET International) established a working group of manufacturing companies (ABB, Emerson, Endress+Hauser, Pepperl+Fuchs, Siemens, Softing, Stahl, and Yokogawa) whose initial task was to define the particular characteristics of process industries. Additional consideration was given to the requirements of NAMUR (an international user association of automation technology in process industries). Besides the extended cycle times, continuous plant operation, and complex actuators and sensors, another major challenge is the sheer quantity of devices (up to 100,000 I/O signals). Moreover, life cycles in the process industry are often very long. It is not unusual to find 20-year old control systems, and many plants are even older than that.

These specific characteristics have always been an impediment to the introduction of new technologies in the past. In spite of this, PROFINET holds interesting prospects for process-related applications and the process industry sector, based in large part on its flexibility. In order to establish PROFINET on a widespread basis, however, the specific requirements of this sector had to be implemented. This effort focused on four main areas:
Investment protection

In order to protect investments, seamless integration into existing fieldbuses must be possible. Many process industry plants have been in operation for several decades and have a large installed base of field devices, controllers, and communication systems. Continued use of this installed base is the aim. How can this be ensured? By means of a proxy concept, the three communication systems encountered in process industries – PROFIBUS PA, Hart, and Foundation Fieldbus – can be integrated into the higher-level PROFINET network. The proxy assumes responsibility for implementing the physics and protocol and ensures the exchange of all I/O, diagnostic, and parameter assignment data as well as alarms with the field devices.

Configuration in Run

Chemical industry

The chemical industry, whose plants operate continuously in most cases, places top priority on plant availability. It is inconceivable that a column would have to be shut down before making a parameter change or replacing a device. It must be possible to reconfigure devices and networks and to add, remove, or replace devices or individual modules during operation. Thanks to the auto-sense and topology detection features, devices are identified automatically and their locations pinpointed. This enables convenient, reliable solutions to be developed for device/spare part replacement scenarios, in which the replacement device parameters are assigned automatically by the control system. All of these “Configuration in Run” measures (CiR) are carried out in PROFINET without any interruption and without adversely affecting network communication. This ensures that plant repairs, modifications, or expansions can be performed without a plant shutdown in continuous production processes, as well.

Time synchronization and time stamping

Power plant

In power plant automation, an especially high value is placed on time-correct tracking of individual process signals. This is especially critical when it comes to malfunctions in individual automation areas. Afterwards, the plant operator wants accurate information on the order in which signals were sent and at what time. He is then able to perform a detailed “root cause” analysis. An accuracy of 1 ms is critical for this purpose.

This requires a time stamp for digital and analog measured values and alarms that is accurate to the millisecond. A precondition for this is an exact time synchronization of the components involved: By means of a central system master clock (e.g., based on GPS or DCF77), a master selected specifically for this purpose transmits a cyclic equidistant clock signal to all bus nodes, thereby synchronizing them. This ensures that I/O devices can provide real-time information about alarms and other important events with a time stamp that is based on a network-wide standardized time of day. By acquiring events at a comparable time, an exact description and analysis of a possible fault can occur. Because not every field device has such a time stamp, a hybrid operation must also be possible. This is guaranteed.

Scalable redundancy
To avoid automation failures caused by conditions such as wire breaks or short circuits, redundancy concepts were developed for PROFINET, which can be structured differently depending on the application (“scalable redundancy”). The basis for these concepts is the automatic switchover of communication paths to intact paths in the event of a fault, along with communication of status information regarding the cause of the communication interruption. The user can decide whether he wants to use controller redundancy, network redundancy, device redundancy, or device interface redundancy. Moreover, the recovery time of a communication system must be fast enough to prevent process disturbances. All redundant elements must have a diagnostic capability so that faults can be detected and faulty elements replaced.

Uniform concept
Many users express the desire for an integrated communication system down to the field level. PROFINET enables a direct path to MES and ERP systems, while at the same time facilitating the use of Internet services for things like remote maintenance, integration of wireless communication, or intelligent network management. New architectures can be realized with PROFINET. The flexible signal allocation allows signals to be assigned to controllers in the PROFINET network without any rewiring. This aids in future plant expansions, even when continuous processes are involved. Over the long-term, this could also make planning of automation systems easier since individual lines can still be expanded even during the commissioning phase. Entirely new paths are also possible: if, up to now, architectures have been based on the layer model of the conventional automation pyramid, flatter and thus more cost-effective architectures are now conceivable, especially for smaller applications.

Outlook
With completion of the “PROFINET for Process Automation” application profile, PI (PROFIBUS & PROFINET International) has taken an important step towards a uniform communication concept for process and production industries. The preconditions for this have been put in place with the implementation of process-specific requirements. What remains now are a few housekeeping tasks, such as the review of security concepts, coordination with FDI, development of test specifications for devices, and certification of devices that meet the PROFINET requirements. Starting in 2011 work can commence on implementing PROFINET products for process automation, thereby opening up whole new prospects for this industry sector.