Integrated Safety And Regulatory Control

Addressing functional safety and regulatory control in a single system has been a challenge for many years – even more so when systems are destined for use in a hazardous area.

A technical solution from Siemens is said to offer these combined capabilities delivering benefits such as a simplified safety verification process, tangible cost savings and scalability Ian Curtis, safety consultant for Siemens Industry Automation, explains.

The functional safety and hazardous area protection world’s are often closely associated. However, when it comes to meeting the requirements of these two complementary yet distinct disciplines in a distributed I/O system, there are many technical challenges to overcome.

A range of SIL 3 capable failsafe I/O modules for the Siemens ET200iSP hazardous area remote I/O station gives users the potential for new safety system architectures which boast simplified engineering and a reduction in the total lifecycle cost for automation and safety.

Early process automation systems were typically distributed but, ironically, with the advent of the Distributed Control System (DCS), system architectures actually became much more centralised. In recent years, there has been a shift back toward a more distributed approach. This same trend has been reflected, albeit to a lesser extent, in distributed safety within the process industry but the recent addition of capability for integrated failsafe I/O in the hazardous area looks set to accelerate this trend.

Given the conservative nature of the industry there are still many users who prefer to stick to a centralised approach, particularly when intrinsic safety requirements are involved. The traditional practice of putting the controllers and I/O in the safe area and using IS barriers, is well understood and still in common use. However the tough economic climate of the last few years has increasingly prompted end users and OEMs to assess and adopt new concepts such as distributed failsafe systems which can actually solve many problems.

The scalability of these distributed systems, particularly those that combine control and safety in the same infrastructure, means they can also be used cost effectively for small process units, OEM skids or rotating equipment with smaller I/O counts.

The distributed approach reduces the need for multi-core cables carrying I/O signals; this means reduced installation effort; reduced risk of wiring errors and simplified bus connection of I/O stations.

SIL3 capability in a Zone 1 hazardous area is a step change that will strengthen the success of distributed I/O systems and really open up new possibilities. Users from the oil and gas industry, chemical industry, and other major hazard industries will look to benefit from the ability to combine configurations that include non-fail-safe modules, such as standard inputs/outputs and relay modules, alongside failsafe modules. Another key benefit is the potential for cost saving through the elimination the ex-barriers, less wiring and space optimisation.

Many OEM suppliers are also exploiting the possibilities of distributed automation in hazardous areas, particularly when they market their products to target emerging markets. If the end customer's employees lack expertise, the use of a centralised configuration often leads to wiring errors - and a lengthy commissioning phase.

When the ET200 iSP remote I/O station is located directly at the machine, or process skid, commissioning is straightforward and the space savings are considerable. As complicated and space-consuming as the earlier approach was – with remote I/O cables, terminals, and ex-barriers – this marshalling effort can now be completely eliminated. It is also easier to achieve the redundancy required in many applications: The ET 200iSP is connected via RS485-iS in hazardous areas. The path from the CPU in the control room to the field can also be redundant. Digital and high availability requirements are covered thanks to bus use.

Because of an increasing popularity with the OEM market, if an end user doesn't start out with distributed safety as a strategy for their plant they often “inherit” it as process skids and OEM type equipment come equipped with their own safety systems.

The first large customers for the ET200 iSP F-modules have been from the oil and gas industry. They have used the fail-safe modules in water-oil separating equipment and tank farms. Other early adopters have come from the chemical industry. Offshore projects generally also lend themselves to distributed safety and the combination of failsafe and hazardous area capability afforded by these new modules will be attractive for such applications.

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Wireless Level Switch

Emerson process Management reports that intelligence inside its switches are now also able to distinguish between material build-up on the fork and a high product level, reducing the need for inspection in the field. Electronic Device Description Language (EDDL) is used to enable the level switches to be configured and monitored from the same device management software as a plant’s other intelligent devices such as pressure and temperature transmitters.

Adding hardwired level switches into an existing plant can be costly due to the cost of laying and connecting new cabling, as well as possibly additional cable trays, system input cards, and system tag license costs.

Many tanks around the plant will not originally have been fitted with instrumentation connected to the control system. Similarly, coolant and lubricant level in various assets have not been monitored continuously. Using wireless technology this type of information can now be better utilised.

Wireless level switches overcome the limitations of hardwiring. They can communicate using the IEC 62591 (WirelessHART) protocol and can be deployed without running cable or using up spare wires and system input cards. Because there are no wiring connections to be made, commissioning is also easier.

A wireless level switch will share the same network infrastructure as other wireless transmitters, with information transmitted via the same gateway. One gateway can support up to 100 IEC 62591 transmitters. Once a gateway is in place, plant personnel can expand the network at will, enabling level switches to be installed on points previously not monitored by the control system, to enhance operation and worker safety.

Because IEC 62591 devices all use the same common application protocol, devices and gateways from different manufacturers should work together seamlessly, self-organising to form a mesh network where each device maintains communication with multiple neighbours – establishing multiple communication paths and relaying data even from the most remote devices all the way to the gateway. If devices are added or removed, the network is able to automatically adjust its communication path, without interrupting data flow.

Modern DCS will have native support for wireless. However, older control systems can also make use of wireless level switches, or other IEC 62591 transmitters, using a wireless gateway that converts the signal to Modbus/RTU, Modbus/TCP, or OPC. Wireless support on the control system engineering console is not required as the network setup is done through a web server embedded in the gateway and devices are configured through intelligent device management software. No additional software needs to be loaded onto the control system or other PC for operations or security. All that is required are the existing HART configuration tools, including asset managers and hand-held configurators, to bring the network online.

A vibrating fork level switch operates on the principle of a tuning fork. An internal piezo-electric crystal oscillates the external fork at its natural frequency. The frequency changes depending on the medium in which it is immersed and these changes can be monitored. Unlike many other level switch technologies, the vibrating fork technology does not have parts that can get stuck and therefore is less prone to failure.

With a simple on/off signal from a hardwired float level switch it was not possible to tell the difference between a stuck switch and an actual high-level condition. Similarly, it was not possible to tell if the level switch was damaged or had failed and the signal was therefore invalid. For this reason, technicians are periodically required to go to the field to perform checks just to be sure, often to find nothing wrong.

With intelligent devices, however, changes in frequency are used to detect high or low level, as well as media build-up on the fork, external damage to the fork, internal damage to the piezo, and excessive corrosion.

Having such intelligence in the field can reduce the necessary trips to the field for inspection purposes, as many suspected problems can be remotely verified from the control room, and cleaning or service scheduled accordingly.

Remote set up
Remote setup is a relatively new development in level switches. Manufacturers can now use EDDL to define how a device is to be displayed in the system. This technology is used for continuous devices such as transmitters and positioners as well as with discrete devices such as level switches, on/off valves, and electric actuators.

The use of EDDL enables IEC 62591 level switches to be set up and checked using the same intelligent device management software as the other devices in the plant. The information from level switches can be displayed side-by-side with information from wireless transmitters for pressure, temperature, and other process parameters. They are displayed the same way as FOUNDATION fieldbus and PROFIBUS devices.

Systems based on EDDL are said to make managing the mix of devices easier, eliminating the errors and learning curve associated with using different software or different driver for each one. Manufacturer know-how, in the form of text and illustrations, is brought into the system through the EDDL file.

A device overview page will clearly indicate the process state as ‘wet’ or ‘dry’ and this is accompanied by device health status, which will indicate the validity of the information. Because the operator is able to tell the difference between media build-up on the fork and an actual high level they can act accordingly.

Material build-upon the fork can be detected in its early stages and flagged as an advisory alarm, so that cleaning can be scheduled before build-up accumulates to the point where it causes a false process state indication. As a supporting troubleshooting tool, the fork’s frequency is also displayed as a dynamic needle gauge with a colour band on the scale to distinguish normal from abnormal operation. The health of the internal power module is also indicated.

EDDL is key to interoperability, providing complete access to all device functionality through a hierarchical menu structure. The EDDL file from the device manufacturer is copied onto the system to tell it how to interface with the device. Unlike other device integration technologies, no software installation skills or license key management are required.

Each version of each device from every manufacturer has a unique EDDL file. There are no shared files, ensuring that the addition of a new device will not overwrite another. Because EDDL is a compressed text file, independent of the Windows operating system, existing device files are not made obsolete by new Windows versions. Conversely, new device files do not force a Windows upgrade for the system.

Time delay can be configured to minimise false switching due to turbulence or splashing, such as in the presence of agitators. To set the delay time on traditional level switches they must be opened up and a potentiometer adjusted by screwdriver. This is inconvenient in the field and exposes electronics to potentially harsh environments. With a WirelessHART vibrating fork level switch, the delay time and other settings can be checked and adjusted remotely from the control room, with the EDDL technology enabling the device management software to maintain a single audit trail for all devices, including level switches where configuration changes are logged.

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SCADA Virtualisation

Virtualisation for SCADA systems brings many benefits such as time and cost savings, greater levels of security and operational efficiency advantages. Tony Chapman from Siemens Industry Automation highlights some of the key areas where SCADA virtualisation can add real value.

As automation solutions become increasingly complex, it follows that the effort required to maintain both hardware and software will also increase. PCs must be provided with suitable specification and operating systems to support the applications. Whilein operation, these systems must be constantly reviewed and updated normally through the application of security patches, updates and service packs. This will apply to every installed system and application program during the lifetime of the system.

To reduce the amount of ongoing administration and maintenance effort associated with update issues, the automation world is turning increasingly to virtualisation and the opportunity it provides to decouple applications from hardware.

This creates the ability to centrally manage the application and simplify back up and restoration of the system environment. Client environments can be installed just once and distributed among one or two virtualisation servers using virtual sessions (instances). It is also easier to implement IT security solutions on central virtualisation servers than via numerous client stations. Virtualisation also eliminates the restriction of target devices to a particular hardware, allowing more complex applications to run on simple, low-cost, and robust thin clients.

Virtualisation
A new service pack for Siemens’ Simatic WinCC Version 7 SCADA system promises owners of automation solutions, the means to reduce hardware, administration, and maintenance costs. One of the innovations of the system is the virtualisation option for both WinCC clients and WinCC servers on various hardware platforms. Through this option, owners of medium and large automation solutions, as well as smaller multiple station and single station systems can reduce hardware, administration, and maintenance costs.

The virtualisation is based on VMware ESX(i) 4.1 - one of VMware's globally-established hypervisor applications for virtualisation. It is installed on central (and ideally redundant) virtualisation servers with adequate performance in order to ensure appropriate background allocation of available system resources (CPUs, work memory, storage media, communication, etc.) among the virtual client and server applications.

This type of virtual server can accommodate up to 25 virtual client sessions of different types without these sessions affecting each other – all on a single hardware platform. Access to these virtual client sessions is via Ethernet using a standard Remote Desktop Protocol (RDP) session. This means that there is no longer a need for powerful client side hardware, which opens the door for the use of simple, compact, and low-cost thin clients, such as robust PDAs or panels without rotating parts, e.g., with Solid State Disk (SSD), for operator control and monitoring in the field.

As a result, it is much easier to choose a client and to use clients in harsh industrial environments, including hazardous areas. If a failure occurs, it is possible to use a thin client with higher or lower screen resolution without making any additional settings, which minimises downtimes.


Consolidation reduces costs
The ability to operate several WinCC servers and/or client sessions on a central platform (also away from the field level) reduces PC hardware and network components, as well as acquisition costs and ongoing operating costs for power/maintenance/spare part considerations. The number of client sessions is limited only by the performance capability of the virtualisation server and not by the SCADA system.

One advantage of virtualisation is that the operating system and automation application no longer has to be individually installed and maintained on every client. Virtualisation reduces this to a one-time installation or a central updating of the VMware and of a small number of different client sessions on the server. The latter can be easily replicated so that the benefits increase with the number of clients. Backups and systems restores are made centrally and in a short time. In addition, it is possible to migrate existing, completely configured systems to a new hardware platform without a time-consuming installation process.


Protection from malicious software
Every inadequately protected operator control station having a USB port, floppy disk drive, or hard disk drive is potentially vulnerable to a certain degree to malicious software and requires more effort in this regard than a virtual system solution. This is because the lack of interfaces in simple thin clients makes them generally less vulnerable to malware than "fully-fledged" PCs. Providing security at a central location requires less effort, quite apart from the fact that the operating systems of professional server solutions, which frequently are not Windows-based, are generally at a lower risk.

Certain hardware and software errors can cause the PC system itself to fail, thus rendering operator control clients inoperable. This calls for a replacement, which is not always possible without interrupting the active process. In virtualised solutions, it is possible to achieve high levels of availability – even when system components require replacement – through the use of RAID systems. Software can be updated during operation, clients can be added to or removed from the system, and the switchover from one client to the other can take place within a few seconds. In addition, a configurable alarm management function is available which notifies the operator in the event of system errors or when critical system loads are reached. All of this contributes to high availability and productivity.

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An alternative to DCS or PLC/SCADA?

Traditionally, users have had a choice between a DCS or a PLC/SCADA approach when selecting a control system for use in process control applications. Richard Sturt, Rockwell Automation business development manager, process Industries, believes that Rockwell can offer a solution for users needing elements of both of these approaches.

A key benefit of traditional DCSs was that the suppliers took a ‘systems approach’ and it was designed for large scale applications. Much of the work of integrating different parts of the system was taken care of by the DCS vendor by using a single database for the complete system.

The DCS approach is to configure the system using standard control objects and faceplates, reducing engineering and providing standardisation. Most DCSs also offer fieldbus communications, tools for process optimisation and asset management packages to improve maintenance. More recently DCS suppliers have introduced more scalable solutions for smaller applications

However, there are a number of potential shortcomings in the DCS approach. Many process plants have a large number of OEM packages that need to be integrated with the overall process control system and it is unlikely that the OEM will use a DCS for their control system. In some manufacturing processes there is a requirement for different types of control; process, discrete, high speed, drive control, motion control or machinery safety. The DCS is not designed to cope with these types of applications and, if a manufacturing process covers multiple disciplines, the DCS will only ever be suitable for part of the system.

DCS has, traditionally also been an expensive product to support throughout its life. Annual licensing and support costs can become a significant part of the overall cost of ownership. The majority of DCSs are engineered and supported by the original manufacturer and are not freely available though other channels, leaving the end user reliant on its DCS vendor.

Most DCSs had closed and proprietary system architectures. More recently suppliers have adopted more open standards but, in many cases, this approach has limitations which often makes it complicated to integrate with MES and other business systems.

The PLC/SCADA approach
Although PLCs were originally developed for discrete applications, most cover a wide range of applications. The term Programmable Automation Controller (PAC) is now used to describe many products to distinguish them from older systems that were focused on discrete logic. This flexible approach offers multiple programming languages, open communications, and scalability for different applications. There are many systems integrators able to integrate PLC/PAC technology, often with specific industry or application knowledge. This approach is also ideal for OEMs who can select a cost effective product to meet their requirements.

Although PLCs and PACs have become more powerful they still have a number of features that are missing when compared to the DCS approach.

A typical PLC/SCADA system has at least two databases. The user has to configure the PLC database and then separately configure the database in the SCADA system. At initial engineering stages there may be an option to import the PLC database into the SCADA system but this will require manual modification as changes are made during commissioning and when enhancements are made. If additional software packages are required they are likely to have their own separate databases too, that will need to be configured.

Another potential weakness is that not all PLCs have features required for demanding continuous process control applications. In some cases they will lack the ability to modify the system on-line or will not include high availability features like redundancy from I/O modules to supervisory systems.

Process optimisation and asset management is another area where traditional PLCs may be lacking compared to a distributed control system.

The best of both worlds
A true ‘Plant-wide Automation’ approach takes the best features from DCS and PLC/SCADA systems and combines them into a single system. It combines the ‘systems approach’ of a DCS and flexibility of a PLC/PAC to provide a solution for multiple applications.

This approach has benefits that can improve plant performance and reduce costs. A single architecture can be selected for any application whether it is continuous process control, high-speed OEM equipment or a small batch reactor. It simplifies integration and reduces engineering costs. The resulting system will have a seamless communications architecture allowing access to plant data for process optimisation, asset management and integration with MES. Support costs will also be minimised by reducing training requirements and the cost of holding spares.

Rockwell Automation has recognised the benefits of combining the features of Distributed Control Systems and PLC/SCADA solutions into a single Plantwide Automation system with its PlantPAx. As part of the companies Integrated Architecture, it allows a single architecture to be used for a wide range of applications, including process, batch, drives, motion and safety.

The importance of being able to address such a wide range of applications is key to a truly plant-wide automation system. Operating any combination of these applications through a purpose-designed single architecture and software environment makes it possible to achieve the benefits of both a DCS and a PLC/SCADA system without many of the traditional downfalls of either. It is this seamless inter-operability that makes plant-wide automation systems so effective.

At the core of the PlantPAx is the single database that is used for the Controller, HMI, Historian, Batch Management, Asset Management and Business Intelligence Tool/Reporting Package. Any data created in the system is instantly accessible to all the software packages that need it and a single security model simplifies the management of user’s profiles.

The key principles behind this solution can help to drive a lower cost of ownership. Using a single architecture reduces initial engineering and integration costs. The process optimisation and business intelligence tools help to maximise plant efficiency.

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Expansion Advantages of Wireless Controls

Josh Thompson, principal, Point Source, says that wireless networks provide facility managers with a number of options to both save money and expand into areas they might not otherwise have been able to reach. After all, running a wire requires additional materials and a hole in the wall.

"The current cost of materials, conduit and cabling can push the BMS outside of the return-on-investment window. Wireless fixes that in many cases," Thompson says. "In an industrial facility, there are applications where sensors and controls would be desirable, but due to hazard containment, penetration of the hazard space is not possible. Wireless solves this problem."

That concept of reaching the hard-to-reach places also applies to security, says Gislene Weig, associate, Syska Hennessy.

"When they have a problem getting cable to certain locations and they want to put in a camera, then we would use wireless," she says.

There are additional wireless applications in security. RFID systems allow for tracking of inventory or equipment that isn't used in a stationary location. In health care, many maternity areas of hospitals have tracking bracelets that use RFID to ensure that babies stay in the area. If a baby is taken too close to the door, an alarm sounds.

Remote Control

If all you want in the way of remote access to building automation systems is the ability to log in after hours, that doesn't necessarily require a wireless system internally. But remote data collection on a real-time basis is another big plus of wireless systems, says Myers, using the example of a property manager in a multi-tenant building being able to pull electricity use data from a submeter by walking down a hallway, instead of having to enter individual units. Being able to leverage that real-time data is where the real payoff comes in.
"The applications where you can see return on investment would be in your energy management, your lights, your shades, your mechanical, your room on/room off times, your integrated HVAC and electrical scheduling, your peak power scheduling for operating purposes," Thompson says. "That kind of information, that kind of intelligence on the building that is not specifically life critical ... if properly integrated and commissioned, you can see huge ROI very, very quickly just in energy savings."

The growing use of wireless devices has produced, along with gains in flexibility and energy savings, some surprises for facility managers. In one building, Myers says wireless thermostats Velcroed to cubicle walls became a little too popular with staff who worked in the spaces controlled by the movable devices. When they were relocated, they took the thermostats with them.

" When they walked away with the thermostat, it lost touch with the zone it was supposed to be controlling and didn't do anything, basically," he says. "With a couple of these occurrences, they had trouble controlling the temperatures on the floor and couldn't figure out why nothing was working until they realized they were moving with the thermostats."

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The Greatest Impact On Automation And Controls In The Next Five Years

Software abstraction – Graphical system design is a great example how software abstraction increases the productivity of engineers and scientist from different industries and application areas.

 

Embedded processing – The ever increasing processing performance and the lower footprint of processors enables companies like National Instruments to bring technologies like multi-core processors into the industrial space and create off-the-shelf embedded systems that engineers and scientist can adopt for the most demanding applications.

 

Reconfigurable hardware – With shorter design cycles and increased pressure to innovate, reconfigurable hardware like field programmable gate arrays (FPGAs) provides the industry with a solution to create custom functionality with hardware performance without the investment and effort of designing an ASIC or custom board. Embedded in off-the-shelf systems and programmable with high-level design tools like NI LabVIEW software, these technologies are accessible for engineers and scientists with little embedded expertise.

 

The combination of a real-time processor, programmable logic and modular I/O within one system – National Instruments refers to this technology as RIO technology but we see a wide adoption for this concept in the industry.

 

Proliferation of Sensors - High-performance measurements are the key to solving sophisticated control problems and realizing robust systems. New technologies and the wide use of sensors in commercial products like smart phones or the Wii gaming console (and many others) have been increasing the availability of sensors and reduced the cost. This trend will continue and so we will see a proliferation of sensors in industrial applications.

 

Networking, synchronization and security – The increasing number of embedded and control systems used to solve today’s applications also increases the need for networking, synchronization and security technologies. And while there are a lot of different standards available today, the integration is where we expect a lot of innovation over the next couple of years.

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Automation Market of National Instruments Products

National Instruments provides products and platforms that enable engineers and scientists to design any system that needs measurement and control, using the graphical system design approach. In this effort, we design products that can be applied across many different industries and application areas. In fact, no particular industry accounts for more than 15% of NI revenue.

 

Industrial automation is of course an important element of the NI business and we have a lot of customers who are using our industrial grade embedded platforms to implement advanced control and monitoring applications; ranging from automated pipeline welding machines to building control and monitoring systems for turbines.

 

National Instruments will continue to invest in products and platforms that can be applied in industrial automation applications. The core strength of the NI graphical system design platform is the combination of productive software and high-performance hardware. In the industrial area these tools are especially beneficial for developing high-performance machines and devices that require advanced sensor feedback, are characterized through challenging control tasks or have quick time to market requirements. Because those kind of advanced applications often require integration into an automation process, National Instruments products can also accomplish lower-speed process automation tasks.

 

Like the PC and smart phone, most disruptive ideas combine existing elements in a way that provide a dramatically better solution. The same phenomenon is true for the smart grid. Embedded reconfigurable instrumentation and control systems powered by NI LabVIEW software are merging with cloud-based networking, analytics and other cutting-edge information technologies. The proliferation of smart networked embedded systems, widely distributed throughout the grid, will revolutionize the way electricity is produced, consumed and distributed.

 

Many of the industry leaders in smart grid technology around the world are using NI technology for designing, prototyping and deploying the embedded systems needed to transform today’s energy networks into smart grids. The Energy Summit at NIWeek 2011 brought in some of those experts to discuss challenges and solutions around smart grid technology.   

National Instruments has some powerful technology all centered around graphical programming using the company’s LabVIEW software. NI products are great for designing, prototyping and deploying embedded systems quickly.  At NIWeek there were many demanding applications demonstrated that were made possible using the high performance capabilities delivered by NI products.

 

Creating industrial control and automation applications is easy and intuitive using LabVIEW.  The drawback is that NI hardware and software has a high price tag compared to typical industrial control and automation products. National Instruments products are like driving a fine sports car - they are responsive and high performance, but expensive.

 

NI is supporting industrial communications with the most recent being EtherCAT.

 

In demanding industrial automation and control applications, NI products make sense for industrial automation and control.

 

I have been intrigued by NI FPGA based products since they were introduced, but they have been pricey. The newest FPGA controller offering is approximately $500 list price.

 

National Instruments is not a mainstream industrial control and automation product supplier. However, NI products are being applied in very high performance niche applications.

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