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Contents A6 Ensuring SCADA/HMI cybersecurity Critical industries, such as chemical, energy, transportation, and water/ wastewater depend on supervisory control and data acquisition (SCADA) systems for daily operations. Strengthening weaknesses in these systems must be a priority and is a shared responsibility.

A10 Optimize manufacturing value in real time If you have the engineering resources and the business commitment to improve your value-add to the business, then real-time process optimization (RPO) may be right for your organization.

A6

A14 Simplifying drive-based and controller-based automation Powerful drive- and controller-based innovations for kinematic application development and integration offer motion control choices.

A18 Tracking HMI advances In addition to holding on to past advances, HMIs continue to evolve.

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A21 Evaluating servo system performance Servo system selection criteria involves more than just wattage and price.

C OMMENT A new niche for AppliedAutomation

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why industrial networks are so vulnerable, eginning in the February 2017 issue, where to turn for cybersecurity guidance, best AppliedAutomation is focusing its coverpractices, and steps to take to protect SCADA age on application stories and case studand HMI. ies. We will examine how you apply autoReal-time process optimization (RPO) mation, instrumentation, and control theo- 20 06 1 6 0 is the focus of the second article in this ries and techniques to help your facilities issue. RPO is commonly confused increase capacity, enhance design with advanced process control and production, improve efficiency, (APC), but they are complemenincrease profitability, and avoid reguyear N tary functions, not equivalent. The third latory consequences—every day.

A I V E R S article is a motion control feature that The cover story in this issue of compares drive-based and controller-based Applied-Automation explains risks associated automation. According to the author, “Machine with cybersecurity for supervisory control and control topography dictates how a motor or data acquisition (SCADA) and human-machine motors move an axis or multiple axes.” interface (HMI) systems. The author explains

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ON THE COVER Industrial firewalls are essential on any network to monitor and restrict data. They must be secure and IT-friendly. Additional features, such as metal housings, a wide temperature range, and Class I, Division 2 approval make them even more suitable for use in factories or in the field. Courtesy: Phoenix Contact USA

Applied Automation December 2016

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C o v e r s t o ry

Ensuring SCADA/HMI cybersecurity Critical industries, such as chemical, energy, transportation, and water/wastewater depend on supervisory control and data acquisition (sCADA) systems for daily operations. strengthening weaknesses in these systems must be a priority and is a shared responsibility.

Mariam Coladonato Phoenix Contact USA

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he U.S. Dept. of Homeland Security (DHS) has identified 16 critical infrastructure sectors that are “so vital to the United States that their incapacitation or destruction would have a debilitating effect on security, national economic security, national public health or safety, or any combination thereof.” These include the chemical, critical manufacturing, energy, nuclear, transportation systems, and water/ wastewater sectors.

According to a DHS report from the National Cybersecurity and Communications Integration Center and Industrial Control Systems Cyber Emergency Response

Team (ICS-CERT), the ICS-CERT team responded to 295 cyber incidents in U.S. fiscal year 2015, a 20% increase over the previous fiscal year. This included 95 incidents within critical manufacturing, 46 within the energy sector, and 25 within the water and wastewater systems sector.

These industries rely heavily on supervisory control and data acquisition (SCADA) networks for day-to-day operations. If national security is only as strong as its weakest link, the SCADA networks in our critical infrastructure might be that weak point. Strengthening the weaknesses in these systems must be a priority and is a shared responsibility.

The U.S. government has issued several guidelines and recommendations to help secure these critical industries, but most are vague and unenforceable. More than 85% of U.S. critical infrastructure is privately owned or operated, so it is largely up to the infrastructure operators to prepare action plans of prevention, mitigation, incident management, and response.

Why industrial networks are so vulnerable

Figure 1: Industrial firewalls are essential on any network to monitor and restrict data. They must be secure and IT-friendly.

Additional features, such as metal housings, a wide temperature range, and Class I, Division 2 approval make them even more suitable for use in factories or in the field. All images courtesy: Phoenix Contact USA

A6 • December 2016

Applied Automation

Many of these SCADA systems have been running for decades. This legacy equipment was designed for the needs of the operational technology (OT) department, rather than the information technology (IT) department. IT and OT traditionally have had different priorities when it comes to security. IT is tasked with protecting a company’s data, so confidentiality is the main concern. The OT world was designed for ease of use, data availability and integrity, and uptime, but not necessarily for security.

When programmable logic controllers (PLCs) were introduced to the market decades ago, they solved a specific set of problems: easy maintenance in the field, high uptime, and a life span of 20 to 30 years.

In the past, this was fine, because PLCs in the field were typically air-gapped, or isolated from other zones.

However, in today’s connected world, this isolation is no longer the case. Even an air-gapped, stand-alone system is vulnerable to infection from a universal serial bus (USB) device.

Industrial protocols also present risks because they were not designed with security in mind. Because many of these protocols have been in use for decades, it would be a daunting task to add security at this point. It would require coordinating updates with hun-

dreds of vendors who manufacture products for those protocols and ensuring interoperability of the devices installed around the world.

The growing use of industrial PCs (IPCs) and other humanmachine interfaces (HMIs) leads to more vulnerability. While the IPC is built to withstand industrial conditions, it still might be running a commercial version of Windows, so it is susceptible to all of the vulnerabilities that come with that operating system. At least one out of three devices is still running Windows XP, which Microsoft no longer supports. Running antivirus software is difficult and expensive to maintain in an industrial environment, so if a virus infects an IPC, it could affect an entire system.

Where to turn for cybersecurity guidance Both the public and private sectors understand how important it is to increase the security of these systems. In February 2016, the White House established a commission on enhancing national cybersecurity with the goal of strengthening cybersecurity in both the public and private sectors. In addition, many industries have formed cybersecurity awareFigure 2: A demilitarized zone (DMZ) separates two networks in this diagram. If, for ness groups to share experiences example, the office network is infected, the DMZ firewall will prevent that infection from about the importance of cyberspreading to the control side. security, develop recommended practices, and create guidelines to n The International Society of Automation (ISA) show asset owners how and where to start taking respontogether with the International Electrotechnical sibility for security in their networks.

Commission (IEC) developed the ISA99/IEC62443 standard for manufacturing and control systems Examples include: cybersecurity. n The North American Electric Reliability Corporation n The American Public Transportation Association (NERC), a not-for-profit international regulatory (APTA) is currently working on Part 3 in its authority whose mission is to assure the reliabilRecommended Practice for Securing Control and ity of the bulk power system in North America, Communications Systems in Transit Environments. created and regularly update a series of Critical Infrastructure Protection (CIP) standards. It is imporn The Chemical Facility Anti-Terrorism Standards tant to note that 11 of the NERC guidelines are sub(CFATS) under DHS is dedicated to chemical infraject to enforcement, making this the only regulated structure cybersecurity. cybersecurity standard today.

Applied Automation December 2016 • A7

C o v e r s t o ry These guidelines rely heavily on Recommended Practice: Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies, a report from DHS, originally released in October 2009 and updated in September 2016.

Steps to take to protect SCADA and HMI

added security, stateful firewalls are still available at a cost-effective price point and do not add significant latency to the network. n Deep packet inspection (DPI) firewalls examine each packet at the application layer and provide the highest level of security. They add latency and are difficult to configure and maintain, so they should be used only in strategic points within an industrial network. They are more common in IT networks, where latency is not as much of a concern.

A defense-in-depth methodology recommends taking a layered approach to cybersecurity. If there is only a single layer of defense, an intruder who knows how to get around that level can easily breach the entire system. For example, if Security information the only level of defense and event monitoris antivirus software, a ing (SIEM) technolonew piece of malware that gies: SIEM technologies has not been detected can streamline the review of slip through the cracks logs, simple network manbecause the software does agement protocol (SNMP) not recognize it. Adding traps, and event managemultiple layers of defense ment. SIEM technologies to a control system will provide a central console minimize the risk of a serifor security personnel to ous incident. review logs from intruConsider the following sion detection systems, best practices for adding firewalls, and other cyberdefensive layers to a consecurity devices. This can trol system: Figure 3: The diagram shows how common internet file system help users comply with Firewall manage(CIFS) integrity monitoring can detect a change on a Windowsmonitoring, logging, and ment: Firewalls should be based system on day zero, which can mitigate damage caused by review requirements. deployed throughout the an infection at a later date.

Demilitarized zones control system network, (DMZs): A DMZ is a proincluding device-level firetected subnetwork between two other networks (see walls at the remote terminal unit (RTU)/PLC/distributed Figure 2). It can be set up between an untrusted network control system (DCS) level (see Figure 1). The potential (e.g., the office network) and a trusted network (the condownsides of this practice are added latency and capitrol network). There are several ways to create a DMZ tal costs, but device-level firewalls will help isolate the network, but the purpose is to make data from the trusted infected or disrupted system if an attacker is able to gain network available to those who need it and who don’t access. For key access points, it is also smart to install necessarily need direct access to the network. multiple firewalls from different manufacturers. If an Patch management: As mentioned earlier, security attacker manages to break through one firewall, there still patch management is difficult within legacy industrial is an additional layer of protection and additional time to control systems, but performing it can fix bugs and close patch vulnerabilities. vulnerabilities. Test these patches on a regular basis—at There are several different types of firewalls, and each least once a year but more often in some cases—in a has its pros and cons. controlled environment, before applying the updates to all individual devices. After patches are tested, verify those n Packet filtering firewalls check the address informaresults with the appropriate vendors. tion in each packet of data against a set of criteria Authentication and authorization: Authentication is before forwarding the packet. While they have low a verification process to ensure that only those people, latency and cost the least, they also offer the lowest devices, systems, or other entities with the proper crelevel of security. dentials can access the network. It is often used along with authorization, which specifies who has rights to n Stateful inspection firewalls track active sessions access data. Technologies and practices to enable and use that information to determine if packets authentication and authorization include: should be forwarded or blocked. Even with the

A8 • December 2016

Applied Automation

n n n n

Role-based access control Challenge/response authentication Physical token/smart-card authorization Biometric authentication.

Malicious code prevention: There are several ways to detect, deter, and mitigate malicious code from infecting a network:

Encryption technologies: The ISA 99 standard recommends the use of virtual private networks (VPNs) to secure remote connectivity. A VPN allows private networks to communicate over a public infrastructure. It encrypts data across untrusted networks and authenticates access into trusted networks.

Common-sense best practices: Technology is critical in securing control systems but doesn’t overlook the human level. SCADA and plant managers need to cultivate a security culture, similar to the safety culture that has become more common over the past decade. Managers should look at the logs and audit them regularly. Set a policy that requires strong passwords and teach employees how to create them. Never use the day, reports device’s default password.

n Antivirus software can be a valuable tool that can detect many viruses, but at the rate malware is being introduced, it is difficult to keep up-to-date, especially in an industrial setting. Another downside is that every IPC must have a unique license Nearly every per operating system, so the costs can add up quickly. are published

that prove how fragile and vulnerable networks are, including SCADA and the operating systems running in ICS.

n Common internet file system (CIFS) integrity monitoring supplements antivirus programs in Windows-based systems and can detect malware on day zero. CIFS integrity monitoring examines file systems to take a baseline snapshot of what the system looks like when it’s clean. Most OT devices are static and have little change. CIFS integrity monitoring goes back on a regular basis to monitor whether anything has been modified. If it detects a change, it notifies the appropriate user. It also prevents installation of third-party software (see Figure 3). n Whitelisting allows the administrator to ensure that only trusted applications can run on the system. To work properly, it requires some administration, but it can prevent malicious files from running.

Virtual LANs: Another technology that can be deployed in networks is virtual LANs, or VLANs. VLANs physically divide networks into smaller, more logical networks to help increase performance and simplify management of the network. A VLAN is actually a network management tool and not designed to detect network security or vulnerabilities. A properly designed VLAN can help mitigate broadcast storms that may occur from hardware failures or cyber incidents.

Data diodes: Data diodes are another access control technology that can be deployed in control system networks. For traffic that needs to be only unidirectional (e.g., operational data being sent to a backup location), a data diode can ensure that no return traffic is allowed back into the protected system. A data diode is a system in which a pair of devices works together; one device has only a physical transmitter while the other has only a physical receiver.

Software within the system handles the generation of transmission control protocol (TCP) acknowledgments that are required for many communication protocols.

Securing the future

Nearly every day, reports are published that prove how fragile and vulnerable networks are, including SCADA and the operating systems running in ICS. These reports explain new cyber-attacks, viruses, vulnerabilities, and even zero days in detail, which can either push the vendor to fix the problem by pushing out security updates or allow attackers to exploit them. ICS cybersecurity is very important, as we count on these systems to bring electricity, clean water, communication, entertainment, and more to our homes.

The implementation of the methods mentioned above, like a multitiered, defense-in-depth approach, addresses the cybersecurity gap in our critical infrastructure, but there is no single entity responsible for the entire process. Other than the energy industry, no other industry regulations are mandatory, therefore the level of protection depends largely on budgetary restrictions in the organization.

An IT administrator’s goal is to maintain the highest level of protection possible in his or her network and systems without interfering with everyday business in which OT engineers must keep the ICS process available and running. At the same time, because both groups must comply with corporate policies, a centralized way to monitor security and manage the network and OS can make their jobs easier and more flexible and efficient. OT, IT, company management, government, and others must play on the same team to ensure that our networks stay secure, available, and accurate.

Mariam Coladonato is the product marketing specialist for networking and security at Phoenix Contact USA. She has worked at Phoenix Contact, supporting the FL mGuard product family, since 2012. Coladonato has a degree in electrical engineering from West Virginia University Institute of Technology, and she is currently pursuing a master’s degree in cybersecurity.

Applied Automation

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R E A L - T I M E P R O C E S S O P T I M I Z AT I O N

Optimize manufacturing value in real time If you have the engineering resources and the business commitment to improve your value-add to the business, then real-time process optimization (RPO) may be right for your organization.

Dennis Brandl BR&L Consulting

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eal-time process optimization (RPO) defines functions that optimize the economic value of manufacturing production processes, such as the minimal cost of production, energy used, or time of production. RPO is commonly confused with advanced process control (APC), but they are complementary functions, not equivalent.

APC is a technique designed to provide control strategies that minimize the difference between process setpoints and actual values; for example, minimizing overshoot in a process change or minimizing the time

to return to a steady state after a process upset. RPO is used to define the target process values for APC, based on optimizing one or more business goals. RPO is used to set target values for many different forms of process control—from basic on/off control, to proportional, integral, and derivative (PID) control, up to the APC techniques of model predictive control (MPC), model-based control (MBC), and dynamic matrix control (DMC). Figure 1 shows how RPO interacts with other aspects of process control and how it fits into the commonly used International Society of Automation (ISA) 95 hierarchy of control. RPO sits above real-time control loops and APC and uses information from many sources to determine the optimal targets to meet economic business goals.

Basic control handles single control loops or sometimes cascaded control loops. APC handles multiple control loops that have interdependencies—a change in one will have an impact on others.

RPO usually spans several units, entire production lines, and sometimes entire sites, setting targets for APC or basic control that meet a global optimum. The broader the scope of RPO, the better the opportunity there is to reach a globally optimal solution, but RPO has been effectively applied to collections of units where economic value can be obtained Figure 1: This diagram shows how real-time process optimization (RPO) interacts with other aspects of process control and how it fits into the commonly used International Society of Automation (ISA) 95 hierarchy of control. All images courtesy: BR&L Consulting

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Applied Automation

using just the bottleneck or production-limiting units. The book, The Goal: A Process of Ongoing Improvement by Eli Goldratt, is a great reference to help understand where and when to apply optimization and should be a required part of every control engineer’s library.

RPO algorithms require multiple sources of information to be effective: Business-defined key performance indicators (KPIs)— these define the economic goals to be maximized or minimized. In most systems, RPO algorithms may need to find solutions that simultaneously optimize several KPIs. For example, there may be a KPI that defines the minimum use of energy to make product, balanced against the amount of material used for production, balanced against the safe operating limits of the equipment. Production KPIs typically involve minimal use of time, energy, or material, or they involve maximizing quality or throughput. The optimization KPIs are set by higher level business functions and can be influenced by economic and market factors, such as customer commitments, spot market prices, sales campaigns, and inventory capabilities.

Process model—a process model describes, in formal mathematical terms, how the system will react to different operating conditions. In the refining industry, a process model may define how well the fractionation columns will split different grades of crude oil. In discrete manufacturing, the model may define the relationship between quality and production line speed. RPO process models are often similar to the process models used in APC, but they include inter-unit dependencies.

Capability model—a capability model describes the capability of the system to handle different raw materials and different products. For example, in processed food production, the difference between different lots of corn in moisture and sweetness can influence processing time, product quality, and energy used. The capability model can be a simple relationship in many manufacturing facilities, but where many different products can be manufactured on the same lines, with varying throughput, quality, material, equipment, and personnel use, then a capability model can be a complex association of materials and resources.

Constraints—define the various limits to determining an optimal solution. The limits may include safety limits for equipment, storage limitations for intermediates or final products, transportation limits for final products, raw material availability and price, or final product price/quantity sensitivity. Each constraint defines one dimension on an optimization multidimensional solution.

Figure 2: This graph shows an example with two variables, five constraints represented as linear equations, and one KPI relationship.

The shape in yellow indicates possible solutions that fit into the constraints. The solutions are at the corners of the shape, and the optimal solution is the one that either maximizes or minimizes the optimization KPIs.

Current conditions—the final element that a real-time process optimization algorithm needs is the current operating conditions. The current condition is used to calculate the cost of changing to a different set of targets. Sometimes it’s better to run below optimal conditions because the cost of switching is too high.

Historical values also are used to see the current rate of change of the system because changing direction can be costly and take significant time.

Optimization methods Optimization is a difficult process when there are dozens of KPIs, hundreds to thousands of variables, and hundreds to thousands of constraints. Multiple techniques have been developed to solve these kinds of problems, and it has been a serious field of study by mathematicians for centuries. There are two ways to look at optimization problems, as linear or nonlinear problems.

Linear problems using linear equations to find optimal solutions is a branch of mathematics called linear programming (LP). If all of the relationships can be represented through a set of linear equations, then LP techniques can be used to find an optimal solution. Figure 2 illustrates a simple example with two variables, five constraints represented as linear equations, and one KPI relationship.

Applied Automation December 2016 • A11

R E A L - T I M E P R O C E S S O P T I M I Z AT I O N Figure 3: This diagram shows a typical lifecycle of a real-time process optimization (RPO) project, where regular model validation and tuning are used to ensure valid targets are generated.

nonlinear, the most you can hope for is “almost optimal,” but usually that can be within tenths of a percent of a true optimal.

Model verification

Effective RPO can bring significant economic benefits to companies, often adding percentage points of profits to the bottom line.

The shape in yellow indicates possible solutions that fit into the constraints. The solutions are at the corners of the shape, and the optimal solution is the one that either maximizes or minimizes the optimization KPIs. LPs that have tens of thousands of variables and thousands of constraints have been built for refinery and chemical plant optimization, while a typical discrete manufacturing facility will often have hundreds of variables and dozens of constraints.

The key to using LPs to discover optimal solutions is the discovery of the linear relationships. Unfortunately, real life is often not linear. For nonlinear situations, there are two approaches; one is to assume that the relationships are linear within the expected solution set and accept that the answer is approximate, but close. Often this is combined with checks to see if the solution is near a nonlinear region and then rerunning the algorithm with a different set of relationships.

The second solution is to run hundreds to thousands of different scenarios, using a strategy called “peak hunting,” in which scenarios are used to “walk” to a local optimal in the multidimensional solution space. Many refineries and chemical plants use the peak hunting method to determine optimal solutions because of the complexity and nonlinearity of the process models. Often, this is combined with checks to ensure that global optimums are found and not just local peaks. When problems are

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Applied Automation

Development of the RPO models can be very time consuming and require a lot of engineering and manufacturing knowledge.

Effective RPO can bring significant economic benefits to companies, often adding percentage points of profits to the bottom line. However, the best models won’t provide the benefits unless they are valid. One of the worst things to happen on an ROP project is to generate targets that clearly won’t work, such as being not safe or not using knowledge of actual current capacities and capabilities. When targets are wrong, the operational staff will quickly start to ignore them, because they will no longer trust the RPO system. It is important to develop a process that is used to regularly validate the models by comparing expected results against measure results. Figure 3 illustrates a typical lifecycle of an RPO project, where regular model validation and tuning are used to ensure valid targets are generated. Most successful RPO projects use data historians to collect data and regularly run analysis programs to determine the actual performance, and they have dedicated resources to validate the models and correct them when needed.

How often to run RPO and validation Real-time process optimization is real time, but real time usually is measured in hours and days rather than seconds and milliseconds. There is little use to run RPO faster than the system can respond to changes in the targets. Often, because the targets are defined by business economics, they will change on the daily, weekly, or even monthly basis. Some industries have faster changes, such as the electric power industry, but most run slower because of the lag in their supply chain. There also is little need to run faster than changes to the demand, constraints, or capabilities. If the plant is running with constant demand, constant prices, and no changes in capabilities, then RPO should find that no changes to process targets are needed.

Validation should be run on a regular schedule or when there are major changes to process capabili-

can be easily distributed, allowing all ties or constraints. For example, if a IIoT is envisioned to devices to participate in discovering the bottleneck machine is replaced with a faster machine, then the model should bring extensive sensing optimal business state.

RPO can be used in companies that be updated with the new capability.

Equipment also breaks or performs and computing capability have a good understanding of their production processes, their dependencies, less well over time, so validation every to manufacturing sites. capabilities, and sensitivities. RPO is quarter, 6 months, or a year is generally best applied to processes where you are a reasonable schedule. Remember, an continually discovering better production schedules and setunvalidated model will quickly become untrusted and not points, and you know that you are not at the best business used, so don’t forget regular validations. use of the facility. If you have the engineering resources Looking to the future and the business commitment to improve your value-add to the business, then RPO may be right for your organization.

A question that often comes up is, how does RPO fit into the new Industrial Internet of Things (IIoT) world? IIoT Dennis Brandl is the founder and president of BR&L is envisioned to bring extensive sensing and computing Consulting in Cary, N.C. He is an active member of capability to manufacturing sites. A manufacturing system the ISA 95 Enterprise/Control System Integration comwill be made up of hundreds or thousands of smart IIoT mittee, a co-author of the MESA B2MML standards, a devices, each communicating and coordinating work with member of the ISA 99 Industrial Cybersecurity Standards other devices. In this world, RPO still has a large benefit.

Committee, former chairman of the ISA 88 Batch System RPO sets the targets for local actions, eventually directing Control Committee, and has participated in the develthe actions of thousands of devices to reach the optimal opment of OPC and other industrial standards. Brandl process state. RPO algorithms will undoubtedly be develwrites a monthly column on Manufacturing IT in Control oped to take advantage of the immense computing capaEngineering magazine. bility of an IIoT cloud. Peak hunting for optimal solutions

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MOTION CONTROL

Simplifying drive-based and controller-based automation Powerful drive- and controller-based innovations for kinematic application development and integration offer motion control choices.

Craig Dahlquist Lenze Americas

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he digital era has been referred to by some as a revolution. However, the long history of manufacturing automation reveals a technological evolution. Within the context of the continually evolving landscape, the requirements for electric motor drive speed control, precision, safety, scalability, and efficiency remain constant. They are hallmarks of innovative machines and robotics.

The rate of adoption for industrial control and automation has been extraordinary, with nearly every factory now leveraging motion control robotics and machine technologies to gain efficiency. Projections show the global robotics industry expanding to more than $200 billion by 2020 (Source: MarketsandMarkets, 2016). Dynamic global markets and supply chain models with shorter production cycles require greater agility to reduce machine development time and turnkey system integration.

Machines with parametric programming, self-optimization, and motion control systems using built-in intelligence Figure 1: This illustration of a controller-based, flow-packer machine shows a delta-type robot picking products from an incoming belt conveyor and organizing them on an outgoing belt conveyor. All graphics courtesy: Lenze Americas

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and software modules are making automation more flexible and efficient. A recent study (Quest Technomarketing, Germany) reports that half of all mechatronic engineers now rely on modular, intelligent machines.

The best innovations simplify work. Managing complexity is a top priority for machine builders, integrators, and operators. Comprehensive tools exist to overcome complexities of automation and motion control. Agile and scalable drive technologies power efficient motion control and enable precise speed control, safety, diagnostics, and maintenance. Human-machine interface (HMI) systems, network connectivity, and other advanced features give machine builders the freedom to design, commission, program, and connect machines more quickly.

Machine control topography dictates how a motor or motors move an axis or multiple axes. In every application, there will be variations in motion control requirements. Choosing between a controller-based versus drive-based machine control is a key design decision.

Essentially, the choice comes down to whether speed and positioning of each axis are controlled by the drive or a main controller making those decisions. While the choice may be obvious for some applications, there may

Both centralized and decentralized drives with built-in intelligence can run independently with internal controls or via digital controls or other inputs.

be multiple options. No litmus test exists. Therefore, it is important to carefully consider the strengths and limitations of both centralized and decentralized automation control.

Controller-based automation A typical controller-based automation system would consist of a main controller and motor drive components connected via a real-time fieldbus. In this scheme, the intelligence resides in the main controller, which constantly conveys, to multiple drives, precisely what position to be in at any given time.

A main motion controller typically controls multiple drives at a 1-millisecond scan rate, whereas a drivebased scheme is normally given logical information at a much slower rate by a master programmable logic controller (PLC). Smaller packaging or food and beverage processing machines are generally controller-based because the drives require relatively low power for the predominantly high dynamic axes. As a machine exceeds four controller-based axes, the cost per axis decreases. Therefore, controller-based machines can have a cost advantage with multiple axes.

A powerful controller-based scheme also offers greater flexibility for running multiple axes applications—from four axes up to an entire factory with 100 axes or more with multiple controllers. In most cases, controller-based applications run between four and 20 axes using a single controller. Robotic and machine applications with three or more axes can run off of a main controller to provide precise coordinated movement. Coordinated motion for robotics using more than two axes may be controllerbased to assure precision in a packaging operation.

For example, a delta type robot might have three outer axes and a fourth axis for picking up products from an incoming belt conveyor and organizing them in some fashion on an outgoing belt conveyor. The main controller would operate all six axes simultaneously for smooth product flow (see Figure 1). In another scenario, a controller-based scheme can operate a four-axis rolling metal machine producing metal downspouts. The single machine can perform all tasks needed to roll and shape flat metal before turning the spout multiple times and positioning it precisely to create offset “S”-shaped crimp-

Figure 2: Modular systems for device-based control combine hardware and software in a high-definition operating system to simplify machine integration and automation. Short setup times can be achieved when machines operate as easily as possible.

ing at the top and “C”-shaped crimping at the bottom.

In another example, a controller-based 10-axis machine could be used to manufacture plastic irrigation pipe, where pipe material is fed repeatedly—indexing and positioning within an area containing blades on either side to cut drainage holes into the material at specified intervals.

Centralized versus decentralized drive-based automation Unlike controller-based drives that cannot operate without controller direction, a drive-based scheme provides intelligence within the drive itself. Both centralized and decentralized drives with built-in intelligence can run independently with internal controls or via digital controls or other inputs.

A centralized drive-based scheme would be a likely choice for synchronous applications, such as winding, camming, positioning/indexing, and electronic gearing.

Drives with enhanced built-in intelligence are capable of making complex calculations and logic-based decisions, as well as communicating from drive-to-drive to perform synchronous functions. In these cases, the physical proximity of the motors to the main control cabinet offers an advantage because all the controls and power distribution are in one central location and can be easily monitored and maintained.

Drive-based control is often preferable to operate larger machinery requiring higher horsepower, such as print-

Applied Automation December 2016 • A15

Motion control Control integration tools ing and other converting applications requiring multiple steps. Electronic gearing must occur between printing Application software tools exist that provide modular, units, so it is critical that the drives are able to communiready-made motion control functions using customizable cate to run at the correct speeds relative to each other. standardized interfaces. Standard machine tasks, such as Synchronous device-based control is a common cross-cutting and winding, and complete robotics modules choice for processing continuous materials, such as can be quickly implemented. Robotic applications, such paper, film, foil, or textiles. There still may be a PLC as pick-and-place movements, are programmed by simple communicating basic start-stop and speed control. parameter settings without requiring knowledge of robotIntelligence in a drive-based system can even migrate ics, which substantially reduces demands on engineering between the drive and a PLC. However, it takes drives and design resources. with built-in intelligence providing logic and the drive-toSolutions built on parameterized programming technoldrive communications to run synchronously. In electronic ogy greatly simplify motion control and machine develgearing, a master drive conveys its position to all other opment from concept to deployment. Parameterization programming allows easier commisdrives, which follow the master drive’s position. sioning than traditional programming.

Synchronous device-based Replacing complex programming with Other applications also can uniform machine-configuration softbenefit from built-in drive intelcontrol is a common choice ware tools significantly reduces engiligence. Winding and unwinding neering time and technical requireby calendering or corrugating for processing continuous machines require constant tenments and eliminates redundancies that can drive up costs. Bringing a sion control and line speed. materials, such as paper, Excess tension or too much slack smart drive online no longer requires can cause defects and even special training, thanks to modular film, foil, or textiles. material deformation. Tension components and engineering tools. control requires slight incremental changes in the speed That gives machine builders the freedom to focus on eleof material winding and unwinding—accounting for ments unique to their projects—differentiators to make changes in the decreasing diameter of the rolled material their products more competitive. on both ends. A drive with built-in intelligence uses an Modular automation systems for device-based control internal drive calculator to continuously track in real time can greatly simplify machine integration and automation. the speed versus diameter to adjust the winding and The increasing individualization of machine control brings challenges to reconcile design lead-times and set-up cycles unwinding speeds accordingly.

Camming is another application requiring precise coor- with productivity. Short setup times can be achieved when machines operate as easily as possible, which requires simdination between axes. For a device to cut accurately, ple operating concepts for machine operators (see Figure 2). the surface material and cutting device must be traveling at exactly the same speed when they contact. Otherwise, No one-size-fits-all some materials will crinkle or tear. Achieving precise coordination between a rotary cutting rod knife and The manufacturing industry stands to gain enormous material, for example, both rotating at variable speeds, benefits from advances in automation. Developing an endcan be tricky. For example, when the circumference to-end automation solution requires a holistic and motionof the knife roll is larger than the cut length, the cutter centric approach. Ultimately, the machine tasks dictate would generally need to speed up while rotating around the drive and control architecture. In terms of drive control and slow down in the cutting zone to match the speed of complexity, the motto should be “no more and no less than material while making the cut. The logic and coordinais needed.” This starts with knowing your options. tion must be constantly occurring between drives in the Choices made during the planning phase will influence drive-based or controller-based architecture. performance throughout a machine’s lifecycle. The design In some cases, machine size may necessitate use of process needs to begin by examining the intended motion decentralized drive-based control. Long motor cables control tasks, forming initial ideas, and taking strategic from a central control cabinet can be eliminated by bring- steps to select the right tools to develop an intelligent and ing power to the decentralized drives in a daisy chain, sustainable concept aligned with the application tasks. drive-to-drive fashion or by feeding power from a source There is no one-size-fits-all motor drive control scheme to other than a central control cabinet. Decentralized drivefit every machine. However, advanced technologies have based inverters can allow for motor-proximity installation. yielded more intelligent and powerful solutions, which Decentralized inverters can enable even large and comtranslate into better choices. plex machines to be more clearly structured, which can be particularly beneficial in applications in the automoCraig Dahlquist is an application engineer at Lenze tive, intralogistics, and other industries.

Americas. He has worked for Lenze since 2003.

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H M I U p d at e

Tracking HMI advances In addition to holding on to past advances, HMIs continue to evolve.

By Clark Kromenaker Omron Automation and Safety

T

he typical application for a human-machine interface (HMI) is anywhere a human needs to interact with a machine or process. We humans are either pushing information into a machine or process and/or pulling or reading the information back. The genesis of the HMI began when it became clear that it was less expensive to program an HMI-type display than to have an electrician wire individual push-buttons and display devices on a machine panel for every machine produced. Early HMI devices were thought of as just that: push-button replacers. They had an object toolbox to match that thought. At that time, basic pushbuttons and indicator lights were the core of the configuring object toolkit.

In the world of control systems, the HMI has progressed with advances in technology and with the rest

Figure 1: Analog touchscreens can respond accurately to input from operators wearing gloves and were used in industrial HMIs much earlier than they were in mobile devices. All graphics courtesy: Omron Automation and Safety

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of the control-system world. The technological trend is to adopt hardware designs that follow the development of commercial computer technologies, such as PCs, laptops, and mobile devices.

There was a time when the processors, memory, and peripheral hardware used in HMI devices were fairly esoteric. Because commercial-grade hardware was relatively fragile at the time, many manufacturers selected military-grade components for the HMI and the rest of the control system. This tended to keep prices high and limit supplies. With the advent of the PC and mobile devices, the durability of hardware components has increased significantly. Not only has the durability of the components improved, but because PCs, cell phones, and tablets have driven volume manufacturing of compact durable components, prices have decreased. Here’s an interesting technology reversal: touchscreens were in use in industrial HMIs far sooner than they appeared in mobile devices (see Figure 1).

On the HMI software and firmware development front, the same tools used to develop the firmware and software that drives the hardware in the HMI has gone through similar changes. Instead of assembly code and X86-type processors, designers can use the latest reduced instruction set computing (RISC) architecture and devices like ARM or ATOM processors, akin to what is used in current mobile devices. The operating systems have evolved as well. Early HMI devices had proprietary operating systems with specific tools and limited familiarity, reusability, and function growth that come with closed systems. Today, the trend is clearly to standardize more open systems, such as Microsoft Windows Embedded 7 (WEC7), where common reusable tools can be used over generations of hardware and where design talent is much more available.

The types of microprocessors used in HMIs have often followed the lead of the PC market. Processors used in the PC market are more easily available at reasonable prices. The same is true of memory and peripheral hardware.

It wasn’t until later that more advanced tools were added. Some of the more advanced tools are graphing objects, trending objects, recipe tools, all the way to more advanced standalone programming languages, such as C++ and VB.Net. The current trend is to automate the HMI screen design process. That process is aided by templates set up with the typical tools and objects for

applications that include logic, motion, vision, safety, robotics, and networks. HMIs are becoming so powerful that we get to where we are today: the possibilities of offloading some PLC functionality into the HMI to allow the PLC to do other things.

What’s hot today?

In the absence of a paradigm-shifting development, what is hot today in HMI technology? Remote-screen viewing of an HMI on mobile devices has caught on with users as well as manufacturers. This function is seen as a way for supervisory personnel to check on what the operator is viewing as well as to collect quick information, such as machine status and production quantities, at any time. For example, a supervisor in a meeting can view the operator’s screen on his mobile device to confirm production status or how a particular process is progressing.

The ability to display media in popular formats on the HMI during runtime is a becoming a must-have capability.

PDF, Xcel, Word, and video format viewers allow the HMI program to display information that can train an operator, help an operator run the machine, or solve a machine issue. For example, a machine jam can log an alarm and then display a video on how to clear the jam and how to get the machine going again.

Being able to share a design or parts of a design is becoming important with the impetus being to standardize the way the same or similar machines, or machine processes, operate within a manufacturing entity. Screens or groups of control objects can be packaged into a file that can be shared with other HMI designers such that standard ways of interfacing with a machine or process can be established that can lead to standardized operator training—even at a global level.

Wide-screen, high-resolution displays are finding their way into many new HMI models. Wide screens have the advantages of allowing more control objects to be placed on the screen and of reducing the number of screen changes, where in a particular process or operation, changing screens would be cumbersome (see Figure 2). However, there can also be the opposite problem when too many control objects are placed on one screen without much forethought. Some may argue that high-resolution displays are not needed in a manufacturing environment. However, for machine builders in a competitive market, a high-resolution HMI control panel can impart higher value to a machine. Either way, with the consumer market driving the volume of displays in the direction of high-resolution, wide screens, these may someday become the most economical and perhaps the only option.

Arguably, the majority of the current crop of programming software for HMI devices is not really programming

Figure 2: High-resolution work displays make interactions more intuitive, allow more control objects to be placed on the screen, and reduce the number of screen changes.

software at all, but more of a configuration package with functionality limited to features the HMI supplier offers in the configuration package. Many HMI providers are now offering the ability to more deeply control the HMI to create custom controls and functionality with more advanced language support. VB.Net and C++ are options in some models. Using these languages allows HMI designers a more direct tie to the underlying hardware of the HMI for faster operating and sometimes more efficient, custom functionality.

Integrated development environments for the HMI, controller, and control peripheral devices are making more sense to design engineers. Separate development/configuration environments where the tags and/or other configuration data must be imported or exported from a variety of configuration or programming packages are being frowned upon. Environments with shared-tag databases and integrated configuration/programming environments are becoming more preferred. For automation suppliers who can provide the entire automation solution, the question is becoming, “Why are there so many programming packages to maintain to use your full solution?” This question becomes tough to answer for automation suppliers who partner with peripheral device vendors to present a complete automation solution as they may need to integrate their own proprietary environment into a completely different one.

Because most of us use mobile devices, the familiarity we have with those devices, the ability to enlarge or shrink an image, and the ability to switch screens with the swoosh of a finger is starting to find its way into HMI devices.

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H M I U p d at e What’s ahead?

stay local to the machine would be control-centric data. The cloud could be used to minimize the information technology (IT) work a controls engineer has to deal with. Today, controls engineers straddle the controls world and IT world with responsibility for rack-mounted servers and switches in cabinets or closets close to the manufacturing area. If it is important to a manufacturing organization to keep manufacturing communications and enterprise data separate, the cloud could assist in this as well.

The cloud might also be a way to ensure that remote locations for a global manufacturing entity that should be running the same control and HMI programs are doing just that. Systems can be designed to periodically refresh their programming or do control program validity testing from a cloud-based master.

Other interesting developments are the continuing miniaturization and improved power efficiency of electronics.

We may see the HMI mounted on the surface of the enclosure for the machine with only small holes in the panel for power and communications, instead of having to cut a rectangular opening in a panel to mount the HMI device. If power-over-Ethernet continues to grow, there would only need to be one electrical connection to the HMI instead of the current two connections of power and communications.

Mounting the HMI on the outside surface of the enclosure would reduce heat buildup in the enclosure, make the HMI easier to install, and would also make it The cloud is introducing easier to meet hazardous location requireentirely new concepts into the ments because cutouts into the enclosure would world of industrial control. be minimized. The next step beyond this may be an on-machine HMI, where the HMI no longer has an enclosure, is mounted directly to the machine wherever needed, and connects to an on-machine communications block nearby or perhaps operates wirelessly (see Figure 3). Further out, with flexible OLED displays on the way and flexible circuit boards already here, we may see HMI displays that are flexible to some degree and can mount on uneven surfaces or displays with improved durability when used in vibration-prone environments.

Concepts are being developed that use eye movements in conjunction with a display to indicate an object or function that needs to be modified. Hand gestures in an active field in front of the display could be used to make changes.

One thing we can be sure of, the ways we interface with machines will continually evolve.

Predicting the future is a touchy topic, but here it goes.

One direction may be the unbundling of features. This market, like many others, is driven by the wants and needs of the end user. Ultimately, the trend of users is to only want and pay for features that they will use. Possibly, at some point, a model could evolve where tools and features are selected for an application, and end users are charged only for what they use.

The cloud is introducing entirely new concepts into the world of industrial control. At some point, we may see some parts of the HMI and control system residing in a private or public cloud. Models may evolve where the HMI or other control hardware itself is either purchased or perhaps leased and based on the functionality needed. Those features would be downloaded to the hardware from the cloud based on unique Internet of Things (IoT) identifier (MAC ID or IP address) or serial number associated with what has been purchased or leased for the device.

The cloud may also be a way to store information that is not directly needed for machine control. Information, such as collected data; required compliance data; operator login, logout, and activity information; security records; product traceability information; predictive maintenance information; recipe information; and alarm histories could be stored in the cloud as a service. The only data that really needs to

Figure 3: In this labeling machine example, the operator interface is mounted directly on the machine.

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Clark Kromenaker is the product marketing manager for HMI, IPC, and RFID at Omron Automation and Safety.

He has more than 15 years of experience in engineering, applications, and marketing for industrial controls and high-technology products.

SERVO SYSTEMS

Evaluating servo system performance Servo system selection criteria involves more than just wattage and price.

By Jerry Tyson and Michael Miller

A test was conducted on an end user’s machine between two different brands of servos with roughly the same outer dimensions (see Figure 2). Although their physical sizes were almost identical, their power ratings differed—one was rated at 750 W and the other at 860 here is common belief that two servos with the W. After multiple tests of the machine’s operation, it was same power range from different manufacturers are roughly equivalent and that the only other sig- concluded that the 750-W motor clearly performed better for this application. This result seems counterintuitive until nificant comparison point is price. This article will you understand that rated torque values are not measured debunk that belief. Important features you can’t at the same speeds for all servos. The equation for the afford to ignore when comparing servos include: power of a motor is expressed in terms of both torque and speed, Rated torque Typical torque-speed curve and neither have standard rated Rated speed 3,500 values for servos in the motion con Overload time trol industry. It is therefore critical to Torque-to-inertia ratio 3,000 select a motor that has the required Resolution 2,500 torque at the machine’s operat Frequency response ing speed and to not fixate on the Network-based solutions 2,000 power rating. A servomotor’s stator Physical size 1,500 windings can be wound to provide Quality and reliability.

B A 1,000 more speed and less torque or Servo torque more torque and less speed at the 500 same wattage.

A servo system’s range is divided 0 into two categories: continuous and 0 2 4 6 8 10 12 14 16 Servo inertia intermittent duty (see Figure 1). The Torque (N·m) continuous duty range represents So far, only torque, speed, the torque the servo can deliver and power have been discussed.

Figure 1: This graph shows a typical torque24/7 without overheating or othInertia is another very important speed curve that compares continuous (A) and erwise damaging the motor. The specification to consider when intermittent (B) duty zones. All graphics courtesy: intermittent duty range refers to selecting a servo. The ratio Yaskawa America Inc. the set of torque values the servo between the servomotor’s rotor can deliver for only short bursts of time. These bursts are inertia and the inertia of the load (the load coupled to typically used for acceleration, deceleration, and dealing the motor’s shaft) is critical. By definition, a servo is a with brief load disturbances. closed-loop system, and its control algorithms are conUnfortunately, torque and speed ratings are not consistent stantly changing the current in the motor. The current throughout the motion control market. The amount of time a sent to the motor is based on complex calculations that servo can continue to deliver torque in the intermittent range involve the differences between its feedback and its com(sometimes referred to as the overload time) varies widely manded values for position, speed, and torque. The ineramong servo manufacturers and is not always clearly specitia ratio between the motor and the load will significantly fied. This feature alone can make a significant difference in affect the servo system’s ability to accurately control the the types of tasks a servo system can perform. When sizing motor. If the ratio is too high, the motor will overshoot its a servo, remember that the RMS (or roughly speaking, the target and cause oscillations. These oscillations can be average) torque requirements must be in the continuous duty minor, such as a slight wiggle when the motor stops, or range for the servo to operate without overheating. The duty major, such as violent and loud vibrations that can damcycle of a servomotor is limited by the heat it can dissipate. age the machine. High-performance servomotors availYa s k a w a A m e r i c a I n c .

Motor speed (min-1)

T

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S e r v o S y St e m S able today have low-inertia, permanent-magnet rotors and can provide a large amount of torque in a small package. It is important to select the proper mechanical transmission (i.e., gearbox, ball-screw, or belt-and-pulley) to achieve a load-to-rotor inertia ratio within an acceptable range: n 10:1 average performance n 5:1 high performance n 1:1 highest performance.

Servo system resolution Another important factor is the resolution of the feedback device.

Encoder resolution is constantly rising. It is not uncommon for encoders to have 20-bit—or greater—resolution. A 20-bit encoder has more than 1 million pulses per revolution (220 = 1,048,576). Remember, the purpose of a servo is to determine the difference between commanded and actual positions and to drive that error value to zero. The higher the resolution, the faster the servo system can detect the movement and make a correction, resulting in more stiffness and tighter control of the load.

Servo system frequency response, bandwidth The servo system’s ability to calculate and deliver current—and therefore torque—in real time can be another area where servos vary greatly. The frequency response of a servo is a measure of its ability to follow changes in the command signal.

A servo’s bandwidth is defined when a sinusoidal signal is commanded into its speed loop, and the frequency of the sine wave is raised until the servo cannot change the shaft speed to match the commanded signal. When the actual speed falls to 70.7% (-3 dB) of the command signal, that frequency is measured as the bandwidth. Over the last 24 years, the speed loop bandwidths of high-performance servos have increased tenfold from levels below 100 Hz to those now exceeding 1 kHz.

Servo system controls Along with advances in power, there have been many improvements in servo system controls. Most modern servo systems have network-based architectures, which lower implemen-

Figure 2: Test stands, such as the one in this photo, are used to measure performance and compare servo system characteristics.

A22 • December 2016 Applied Automation

tation costs and improve diagnostic capabilities. The reduction in wiring also increases the speed at which OEMs can commission multi-axis systems, resulting in higher profits and greater throughput.

Network connectivity for both servo system control and for handling information between the factory manufacturing execution system (MES) and SCADA system is an absolute must in this age of increased communication. The added diagnostic capabilities can reduce downtime and allow for remote resources to quickly troubleshoot problems.

As servo performance has increased, the size of the electronics in the amplifier and controller has decreased.

Thermally efficient designs require less space between amplifiers. These advances help shrink the footprint of the electronics, which results in significant cost savings for the overall system. Smaller control cabinets and the resulting real estate savings can be used to create a more efficient use of the factory floor.

Servo system quality Of course, the aforementioned features are of little benefit if the system suffers from inferior quality. It is important to choose a manufacturer that has a track record of great quality and the data to support those claims. Mean time between failures is a statistical measurement of the quality and reliability of a product. Asking for this information before you purchase can help you choose a motion control partner whose product offering provides a lower total cost of ownership.

There are many factors to consider before purchasing a servo system. The next time you are comparing servos, remember that the criteria for determining true value goes far beyond wattage and price.

Jerry Tyson is the southeast regional motion engineer for Yaskawa America Inc. He has 26 years of experience in the motion control industry and has worked for Yaskawa for 25 years.

Michael Miller is the regional motion engineering manager at Yaskawa America Inc. where he has worked for 16 years.

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Less does mean more!

To learn more, visit www.Lenze.com.

As easy as that.