Hierarchical Control using Smart Nodes

Our new Smart Nodes for WinCC OA is a tool providing the means to efficiently model and operate a system. With Smart Nodes you can keep your process control intelligence tidily organized while automatically providing your system with a homogeneous and effortless way to synchronize processes, perform handshakes, provide role-based multi-user operation and partition (or mask) logical parts of your system. Smart Nodes is the best way to achieve a versatile, efficient and maintainable automation and process control solution. Find here more about our exclusive WinCC OA services.

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Cleverdist staff gained extensive experience using WinCC Open Architecture at CERN (where we recently attended the presentation of WinCC OA 3.12) to develop complex automation, process control and operation systems. CERN has dedicated more than a decade and many hundreds of engineers, programmers and physicists to develop the LHC experiment control systems. A common framework based on WinCC OA was developed by a collaboration comprising all CERN groups working on control systems.

One of the most important and useful parts of this framework is a tool for modelling a system behavior in a hierarchical control node-tree. While most of the CERN framework was written in WinCC OA, for this hierarchical control tool, which is based on finite state machines and expert system-like rules, CERN chose to integrate an already existing and well consolidated tool, i.e., CERN’s State Machine Interface (SMI++). Therefore, CERN’s tool consists of a WinCC OA part which includes an interface to develop and operate the control tree and an SMI++ part, i.e., that is where the state transition rules are translated and executed, commands are processed, etc. This hierarchical control tree tool has been decisive in enabling efficient and uninterrupted operation for all of the LHC experiments.

At Cleverdist, we are well aware of the usefulness of such a tool for any industry involving process control. Hence, with our experience in creating and analyzing system models with hierarchical control tools, we have developed a new user friendly and powerful tool written entirely in WinCC OA and using our Smart Nodes framework, thus making all the WinCC OA scripting power available for the development of the hierarchical control nodes. So how does it work, and why are we so convinced that this tool is absolutely a game changer for your operations/business? Keep reading.

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Similar to CERN’s framework tool, hierarchical control trees based on Smart Nodes are made of two classes of nodes: device classes that model hardware devices with their states depending on the values of the respective modeled hardware, and logical classes, with states depending on their children (being either logical or device nodes) states. Additionally, for each of the states of a particular node type there is a list of possible commands. For device types commands will typically set datapoints that will produce the consequent changes in the controlled hardware. On the other hand, logical types will interpret the received commands and dispatch to each of their children nodes a new command that will depend, for example, on the type of each child. States are propagated and interpreted upwards, while commands are propagated downwards in the hierarchical control tree. A command can come from an automatic action embedded in the logic of control nodes which are triggered by a child node state change, or it could be a command sent explicitly by an operator that can be in control of the whole hierarchical tree (or just a sub-tree). The tool supports concurrent user operation, partitioning of the tree and integration with WinCC OA access control thus allowing different possible commands for operators depending on their privileges.

WinCC OA already has the built-in tools to script all process control for your business. However, with Smart Nodes you can do it in a quick, modular and hierarchical manner, saving you the time normally devoted to ensuring the synchronization/handshake for your different processes and dramatically easing the modification of the logic, process analysis and troubleshooting.

In summary, with Smart Nodes, you can easily create your own expert system using basic WinCC OA scripting knowledge. Alternatively, since Smart Nodes is written natively in WinCC OA and you have access to the whole WinCC OA scripting power, you can choose to connect your nodes to an already existing external expert system, knowledge database, neural network, etc. Interested on a video demonstration? Let us know and we will post one soon! Find here more about our exclusive WinCC OA services.

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