Vendors of process control systems strive to make their systems not only increasingly powerful, but also more user-friendly. This is an ongoing challenge, given the increasing complexity of today’s processes and the extensive range of tasks. The diverse user groups of control systems have different requirements here when it comes to topics like user-friendliness, performance, or efficiency.
The application areas and tasks of process control systems have been expanding continuously. Starting with the control and monitoring of centralised production processes, their capabilities have grown to include such tasks as controlling connected processes, handling energy management, or supporting maintenance teams. The expectations of individual user groups are just as diverse as these tasks: configuring engineers, operators and plant owners each have different priorities in using control systems. In developing the latest version of the Simatic PCS 7 process control system, the developers at Siemens ensured more efficient engineering, more user-friendly working, and – especially for plant owners – increased performance.
More efficient engineering
Simulation is an indispensable aid in shortening project times and thus in reducing project costs: the simulation framework, Simit, also used for virtual commissioning of Simatic-based automation solutions, allows more efficient engineering of the system. By simulating process behaviour, the correct functioning of the automation system can be ensured, within the framework of a factory acceptance test (FAT), for example.
The new selective loading of program codes into the automation systems is also aimed at significantly reducing commissioning times. This new system allows configuring engineers to upload only the modifications they have made themselves. Until now only complete programs could be loaded. Transferring individual changes reduces the uploading time on one hand, and on the other, commissioning can be much more flexible and significantly more effective. This results in lower costs, fewer errors, and increased operational safety.
Not only do individual tasks become more effective, but also the engineering system in its entirety: one way in which this is ensured is with ‘multi-user operator station engineering’, which minimises the coordination effort between the individual configuring teams for large-scale projects. When working in parallel on operating screens, configuring engineers until now had to keep manual modification logs, so that all changes were taken into account, and results were not mutually overwritten. With the new version, there is no need for this coordination, and errors are minimised.
Version 8.1 offers an expanded block library providing standard solutions for even more automation tasks. This also facilitates engineering since in many cases there is no need for complex programming of individual blocks. The blocks in the library only have to be parameterised, and they have the advantage that they can always be further developed within the scope of Siemens service and support measures. They also remain fully functional following updates. The MPC-10x10 block that supplements the previous MPC 4x4 block is worthy of special mention. This model-based predictive controller can now control up to ten manipulated variables and controlled variables. It can be used for simple implementation of demanding multi-variable control tasks. Expansion of the variables enables optimal operation of distillation towers, for example, with regard to product yield and energy use.
A range of further improved details, such as the option of saving centralised colour schemes for operating screens, or the ability to scale the display size of individual block screens, ensure reduced complexity in application-specific configuring, and stronger focus on essential tasks.
More user-friendly operation
During ongoing plant operation, the operating personnel use the control system for several hours a day. Therefore, a further increase in the user-friendliness of the system was a priority in the development activities for Version 8.1 of Simatic PCS 7. The concept of Advanced Process Graphics makes a crucial contribution here. The visualisation module, available till now as an optional module, is now included in the standard version of the system. Its approach is oriented around the EEMUA Publication 201 and the German VDI/VDE Standard 3699 ‘Process control using display screens’. It is aimed at implementing display concepts task-specifically and situation-specifically. Work is simplified significantly thanks to the consistent use of subtle colours, simple shapes and unambiguous picture language, as well as pre-processed plant data in the form of hybrid displays, trend curves, and ‘spider charts’. Instead of the plant operator having to establish relationships between individual values in his head – something that requires attentiveness and is prone to errors – the system presents him with important trends and reliably visualises the overall relationships in production processes. The Advanced Process Graphics simplify the operators’ work, despite the increasing complexity and expansion of the classic operator tasks.
Drastic reductions in screen selection times also ensure increased user-friendliness and heightened attentiveness: picture build-up used to take several seconds, particularly with complex operating screens containing a host of process values displayed in real time. Not only is this dangerous at critical moments, it is also perceived as a burdensome nuisance in day-to-day work. Thanks to improvement measures, even highly detailed and large operating screens with a host of variables can now be built-up significantly faster, contributing a great deal to increased safety and smoother working.
The new version now also fully supports the use of the Simatic HMI Comfort Panels. These local operator units ensure detailed display of process screens, ensure fast picture build-up and offer diverse interfaces, such as Ethernet or USB.
More powerful operation
While user-friendliness is among the most important criteria of a control system from the operator’s point of view, plant owners are concerned with the safe, fault-free operation of the plant, high product quality, and production methods that conserve resources. These requirements have, of course, been taken into account extensively in developing Version 8.1.
More flexibility, faster benefits from increased performance through updates, and interruption-free loading are the primary benefits of ‘type change in run’. What does this mean? Until now, plant owners were always sceptical about block updates: Naturally, they wanted to benefit from the innovations of an improved block library, but was it worth stopping the relevant automation systems and interrupting production? The use of the new CPU 410 and Version 8.1 removes this dilemma. Individual blocks or a block library can be updated without interruption, in the same way as installing a plant expansion, such as the addition of a motor. The automation system no longer has to be restarted for this purpose the way it used to. Plant owners thus benefit quickly from updates without having to worry that production will be interrupted. The same freedom from interruption now also applies for upgrading the system expansion card (SEC). It controls the performance dimensioning of the CPU 410 depending on the automation task. The number of process objects (POs) determines the required performance scope. The range extends from 100 POs to an unlimited number (the CPU is the limiting factor, being dimensioned for almost 2600), and with the introduction of the new version the extension steps have been set to the easier handled figure of 100 units. For plant owners, the innovation not only ensures interruption-free operation of the expansion, it also allows extremely precise adaptation of the performance to the task, and thus helps to save unnecessary investment costs since it is now possible to expand POs at any time, thus making it unnecessary to plan safety reserves.
Version 8.1 also supports different versions of block libraries. This makes stepwise updating of automation systems possible, resulting in more freedom in plant maintenance. Since previously all automation systems had to have the same library version, only related controllers could be supplied simultaneously with block library updates. This involved not only extensive maintenance measures, but also plant standstills.
The new version offers plant owners benefits on yet another decisive point: the option of monitoring mechanical components such as pumps, valves or heat exchangers for perfect operation. This is much more complex than monitoring electronic components and it requires a separate monitoring system in most plants. For the operator, this of course means additional complexity: relationships between the systems must be established and other operating and display philosophies have to be learned. Such separate solutions naturally involve corresponding costs for the plant owner for setting up and operating the systems. The standard library of Simatic PCS 7, Version 8.1, already provides condition monitoring blocks for monitoring such mechanical assets, thus allowing the integration of comprehensive status monitoring concepts directly into the control system – with a consistent appearance and without a separate system. By integrating the mechanical components into preventive maintenance management, plant owners gain valuable information about the status of their plants, avoid unplanned failures, and can also save energy costs thanks to monitoring of the best-possible operating states of individual components.
In future, plant owners will profit from expanded system capacities, particularly in extensive applications or when several operator consoles are combined. An automation project of Version 8.1 or higher can thus contain 18 instead of the previous 12 OS servers, 40 instead of 32 clients, and 100 instead of 50 Web clients. This clears the way for even better adapted system configurations on corresponding plant structures. Further innovations concern topics like IT security. The Simatic PCS 7 overall system was awarded Achilles Bronze status here. The Achilles certification program of Wurldtech Security Technologies Inc. is accepted internationally as the standard for industrial safety. The certification confirms that the overall system has the necessary functions to guarantee safe and stable process operation.
Within the scope of the new version, there are also some hardware innovations of interest to plant owners. Thus, the second Ethernet interface of the standard AS Simatic S7 410 can now be used. This allows implementation of redundant Profinet ring structures without further communication cards. The new Simatic ET 200SP distributed I/O provides significant benefits in user-friendliness, allows high-speed communication via Profinet, and ensures more performance. Its compact size, integrated power module and increased energy efficiency make this distributed I/O device the ideal partner in applications in the water industry or the food and beverages industry.
Siemens has implemented crucial advantages in the new version of Simatic PCS 7 control system. Taken individually and also in their entirety, these ensure better performance and higher efficiency throughout the entire life cycle.
For more information contact Keshin Govender, Siemens Southern Africa, +27 (0)11 652 2412, [email protected], www.siemens.co.za
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