This open interface standard is independent of the manufacturer or system supplier of the application, of the programming language in which the respective software was programmed, and of the operating system on which the application is running. The biggest difference to previous versions is that machine data can not only be transported, but also semantically described in a machine-readable way. OPC UA provides access to a wide variety of data in both vertical and horizontal directions.
The spectrum ranges from OPC UA components directly integrated on the devices and controllers or machines and systems to so-called gateways and aggregating servers. A central challenge of Industry 4. Anyone who wants to advertise with the label of "Industry 4. Information modeling? Many SMEs already stop paying attention at this point - OPC UA is then quickly compared with other protocols and supposed restrictions in deployment scenarios are identified.
First of all: Unknowingly, every equipment and machine manufacturer already provides an information model: Data and interfaces are already available via various protocols.
The new world of devices helps us to understand the "things" faster and easier, because they now offer services, but above all their meaning. This is nothing new in the IT world - but now this service-oriented architecture SoA is advancing into the "Things" themselves. Device and machine manufacturers describe the object-oriented information of their system and also define the access rights with integrated IT security. The machine-builders therefore remain in control of their data or can distribute it in a targeted and controlled manner and thus also participate in big data and analysis in monetary terms.
Definitely you need both variants:. OPC UA combines both. Die casting cells are complex automated production systems that include not only the die casting machine but also other peripheral machines and components. In the German speaking web-seminar "OPC UA for die casting", which will take place on July 24, , - CEST , you will learn about the current status of the work, the organization of the work process, the European partners involved and the lessons learned so far with regard to the coordination with the specifications of other OPC UA working groups.
These online presentations are program: Dr. KG Dr. Transport, Security, Access Rights From an "external" point of view, access to machine data and services should be defined as completely secure in terms of IT security.
The actual transport layer can be extended by additional protocols at any time. The independence from the physical transport medium and the transport protocol is a decisive advantage of OPC UA compared to other pure IoT data protocols. The device or machine builder does not have to worry about this, but only provides the data and services in a secure way. Modelling Machines must offer their data and services in machine-readable form if machines and services are to communicate with each other and if engineering is to be as simple as possible.
The semantic definition of the interfaces can be modelled with OPC UA by the respective professional associations. OPC UA clients, available as PLCopen components in a PLC control or visualization or from the cloud, can now implement identical access to the devices of both manufacturers with extremely simple engineering efforts. If RFID readers from different manufacturers are equipped with an identical interface - is the differentiation of the devices still ensured?
The answer is: No. In addition to the standardized information model, each device manufacturer can offer its own models as an "extra" in parallel. This combination of "device standards" and "device individuality" makes sense and is ideally suited to give competing device manufacturers the opportunity to reach an agreement, but still make their added value available to the users But one thing remains important: An OPC UA client accesses all interfaces - the standardized and the manufacturer-specific ones - with the same mechanism.
This layer of data and service modeling is the real key to Industry 4. Services Irrespective of the purpose of the device or machine, certain services are always available; only a few are presented here:.
Operating System and Realtime Which operating system works on a machine or whether a special real-time implementation is used plays no role for external device and machine communication: None of this is visible to the outside - in an Industry 4.
Nodes are pieces of information for example, a unique temperature and consist of attributes, the actual data value, and one or more references to other nodes, each in its own address space. A unique temperature will therefore take up multiple addresses in an address space.
Nodes are referenced by a unique node ID: a namespace URI unique resource identifier , a data type, and the identifier itself. Each node belongs to a specific namespace. The namespace table stores separate URIs for information models used by individual organizations that have their own requirements for how data should look and behave. There are eight core node classes in OPC UA, including objects physical entities , methods functions that store data when queried , and variables actual data.
Object node classes in OPC UA are the key to how it can create complex data and distinguish between similar but different entities, for example a temperature sensor for an air conditioner and a temperature sensor for a boiler. The standard is a collection of specifications OPC UA protocols that define guidelines for communication between servers and clients, including rules for different functions and data structures.
For example, the Alarms and Conditions specification provides a solution to the challenge of standardizing how event and alarm information is pushed from field devices to applications. The Historical Access specification addresses the challenge of standardizing how historical data is accessed in auditing processes. The Programs specification includes information on how developers should handle return codes in their code, among others. OPC UA is used in industrial systems, for example oil and gas, agriculture, medical and pharmaceutical, critical services like electricity grids and sewerage treatment plants, and IoT systems like smart city applications.
Common OPC UA applications include device diagnostics, asset management, production management, quality control, data acquisition, enterprise reporting, data security, data integration for GUI interfaces, remote worker support, and event monitoring. Real-world examples include monitoring the uptime of security cameras, sending out alerts for malfunctioning sensors, controlling office temperatures, remotely managing automated machines, estimating workloads, linking embedded devices, and supporting remote workers.
For example, OPC UA may be used to push data from embedded devices like temperature sensors to the cloud, for example to analyze usage and equipment efficiency. Where synchronization is needed between devices at remote locations, and resource planning and manufacturing control systems, OPC UA enables vertical data exchange between heterogeneous drivers and high-level applications. OPC UA strengthens industrial security applications.
OPC UA events management protocols may automatically shut down a plant in the event of a cyberattack on field devices, and isolate affected networks or allow limited access to specific networks, enabling business continuity while the attack is investigated. Historically, the automation pyramid in industrial systems is a hierarchical structure that describes the flow of information from low-level devices like controllers, sensors, or meters to high-level ERP applications.
In the opposite direction is a control flow, from high-level ERP applications to low-level devices. OPC UA does away with this pyramid structure by decentralizing system components and facilitating the use of more flexible data modeling structures in a mesh network.
OPC UA achieves this by defining consistent data structures that all components use, for example an ERP application and a field sensor can both use the same information model. OPC UA enables business intelligence applications to source raw data from a wide range of real-time, event, and historical data sources. Historically, industrial systems ran on Windows-based software.
OPC UA is platform agnostic; industrial systems can integrate software from any vendor, using any operating system. OPC UA can be implemented on embedded systems and in the cloud. OPC UA is future proof. It enables organizations to develop scalable SCADA systems so that existing plant equipment can integrate with new software modules without additional configuration. All of these specifications are commonly referred to as conventional OPC.
OPC DA has a simple data model: each data access is characterized by a value, a quality and a timestamp. The value represents the data, the quality indicates its reliability, and the timestamp refers to its freshness.
Data access is standardized using a client and server API. Figure 1 depicts one example deployment of a conventional OPC solution within an industrial system.
The OPC server is an application collecting data from control and field components, such as programmable logic controllers, via their native protocols Modbus, IEC , etc.
Finally, besides data read and write services, the API also enables the discovery of OPC DA servers on the network and the listing of the information managed by each server.
However, conventional OPC suffers from several limitations. Since DCOM technology is almost only natively supported on Windows platforms, integrating an OPC server or client on an embedded machine programmable logic controller, remote HMI equipped with a real-time operating system has proven problematic. In many cases, additional tunneling tools are needed to cross firewalls or bypass complex DCOM configurations. Three types of DCOM permissions can be configured:. The complex implementation of these ACLs, especially in cases where OPC clients and servers reside on remote machines and evolve in different security domains, may lead users to simply disable DCOM security measures by allowing, for example, remote access without authentication.
Another major problem with conventional OPC comes from the use of dynamic port allocation. OPC clients must first connect to the server in order to see what TCP port is associated with a particular object. The clients then create a new TCP connection to the server. TCP ports that can be used by a server can vary from port to , which implies excessively permissive firewall configurations with a high security risk.
Despite the recent development of firewalls that make it possible to overcome this difficulty by dynamically opening the necessary ports via OPC connection monitoring, their use requires additional investments from companies.
The main goal of OPC-UA is to specify a solution for communication between industrial deployments which can be easily deployed on different platforms. This new specification also aimed at preventing configuration and security problems related to conventional OPC while extending data representation via complex object-oriented modeling. Information handled by an OPC-UA server is represented within a typed hierarchical model called address space.
Nodes are the building blocks of the address space. Nodes are typed objects characterized by a set of attributes and one or more references to other nodes.
Object nodes may represent a real physical system, a subsystem or a component. Variable nodes contain a value and may refer to actual data or properties of a node metadata characterizing a node. References between nodes within the address space are also typed.
Thus, a hasProperty reference binds a node to a property while a hasComponent reference represents a membership link between two nodes. Finally, the notion of a view restricts the address space that can be accessed by clients based on their needs. The address space defines nodes that may correspond to actual entities Cuttingtool, Spindle, etc. In total, OPC-UA defines 37 services, of which 21 are dedicated to establishing and managing communication infrastructure and 16 services relate to exchanging information.
These services make it possible, among other things to:. The client then selects the Endpoint that matches the desired security policy.
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