OPC UA – THE BASICS

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OPC UA – all the most important information put together for you in a clear and understandable summary:

  • What is OPC UA? – Definition and importance
  • OPC UA in an Industry 4.0 environment
  • What are the advantages of OPC UA?
  • How does OPC UA work?
  • OPC UA implementation
  • OPC UA and MES

WHAT IS OPC UA? – DEFINITION AND IMPORTANCE

OPC UA stands for Open Platform Communications Unified Architecture and is a collection of standards for communications and data exchange in an industrial automation environment. OPC UA ensures smooth communication between machines produced by different manufacturers, the interfaces and the MES system – also including other systems used at a company. It is a standard for both horizontal machine-to-machine (M2M) communication as well as vertical machine-to-cloud communication.

OPC UA is the latest generation of Open Platform Communications specifications issued by the OPC Foundation and is under continuous development. It is an International Electrotechnical Commission (IEC) standard which is described in IEC 62541.

OPC UA as a communication standard

OPC UA is classified as a data and information exchange standard, resp. an interface standard for the industrial production environment. OPC UA is a globally recognized standard with a service-oriented architecture (SOA). As such, OPC UA offers key advantages: It is platform-independent and not only capable of transporting machine data but also of describing these data semantically in a machine-readable format.

The basic principles of OPC UA

The OPC UA architecture is built on the following four basic principles:

  1. Provision of simple interfaces
  2. Provision of a unified messaging format
  3. Implementation of high security standards and different security levels
  4. Provision of flexible enhancement options

The OPC Foundation

The OPC Foundation, which coordinates and further develops OPC UA, was founded in 1994. It is a global, nonprofit organization with around 450 members from a range of different industries. These include, for example, Siemens, SAP and Microsoft.
In 1996, the OPC Foundation released the first version of OPC – with the first version of OPC UA being released at the end of 2006. In 2008, a revised version of OPC UA was released which was no longer based on Microsoft’s DCOM technology. Since then, the organization has been continually working on further developing and distributing the OPC UA standard.

OPC UA IN AN INDUSTRY 4.0 ENVIRONMENT

Industrial automation, which is increasingly gaining in importance within the context of Industry 4.0, is based on modern information and communication technologies. Only those companies that utilize their resources efficiently, optimize their processes on an ongoing basis and react with a high degree of flexibility are able to remain competitive. Thus, digitalization and standardization not only play an important role today but will continue to do so in the future. A secure, standardized exchange of data and information is the central challenge now facing companies. The OPC UA standard offers a solution to some of the requirements posed by Industry 4.0 – which is why it is so important for manufacturing companies.

WHAT ARE THE ADVANTAGES OF OPC UA?

OPC UA is an architecture that can be flexibly enhanced – thus rendering it future-proof. In a production environment that is becoming increasingly complex, it already plays a decisive role for many companies.

OPC UA offers numerous advantages in an industrial automation environment and for machine-to-machine communication:

  • Transparent architecture for industrial communication
  • OPC UA is totally manufacturer and platform-independent – making a reliable exchange of data between products provided by different manufacturers possible
  • Reduced complexity in the OPC UA environment through standardized connectivity
  • High level of interoperability between different applications
  • Secure and reliable communication, realized through authorization, authentication and encryption mechanisms and others

HOW DOES OPC UA WORK?

OPC UA can be used on absolutely any operating system. OPC UA is, so to speak, the interpreter that translates outgoing machine process data, such as run times, utilization and yields, into a unified standard and makes these available to other systems. OPC UA also works the other way around – transferring the specifications from your Manufacturing Execution System (MES) over to your machines. Through a unified format, a pre-defined structure and a common vocabulary, all your applications are able to understand the messages. However, this communication is not only based on a pure exchange of data but also on the exchange of semantic information.

The OPC UA architecture works according to the so-called client-server principle: The OPC UA server makes data and information available to the OPC UA client. The latter sends a request to the server and receives a respective response. This client-server communication enables data to be exchanged reliably, securely and in an encrypted state.

OPC UA specifications

The OPC UA standard consists of a number of different specifications which is why it is referred to as a multipart specification. Each individual specification describes a sub-function. These specifications also indicate which client and server interfaces need to be implemented.

There are three groups of OPC UA specifications:

  1. Core specifications
  2. Specifications for access models
  3. Additional and auxiliary specifications

The following specifications are of primary importance for the operational deployment of OPC UA:

  • Data Access: This specification describes the exchange of real-time data which is done based on timestamps.
  • Historical Access: This specification allows not only real-time but also historical data to be queried.
  • Alarms and Conditions: This specification is a standard for alarm notifications.

OPC UA protocols

OPC UA uses established data protocols to transport data. For high-performance applications, a binary data exchange takes place via a TCP-based binary protocol. This is required by the OPC UA specification. This means that it is supported by every single OPC UA application.

High level of security through OPC UA

Whilst OPC UA was being developed, the security of this standard was at the center of focus right from day one. OPC UA not only offers protection against unwanted access but also against careless operation. User and application authentication, data encryption and message signing all contribute to making OPC UA a secure communication standard. OPC UA incorporates standards that are also used on the Internet. These include, for example, AES, TLS and SSL.

OPC UA IMPLEMENTATION

For production companies, implementing OPC UA is an important step along the path to introducing Industry 4.0 communication. The VDMA guide shows how this open interface standard can be implemented and where the advantages lie, whereby it can be introduced gradually step-by-step. The basic prerequisite for using OPC UA is a network based on the Internet Protocol (IP). At the same time, the interfaces to all the connected systems and machines must be of a simple nature.

OPC UA AND MES

Smooth, standardized communication is absolutely vital to the successful deployment of a Manufacturing Execution System (MES).

This explains why Böhme & Weihs also relies on the use of the OPC UA standard in their MESQ-it MES software in order to implement a fast, unified data exchange system: Thanks to OPC UA, machine process data acquired as part of the machine data collection process using MDC software are translated into a unified standard and then made available to the MES system. At the same time, OPC UA transmits the requirements stipulated by MESQ-it to the machines in the production environment.

Using standardized components, MESQ-it is able to integrate different systems and machines manufactured in different years to create an individual solution for the respective production environment. Through interconnecting their MES systems and machines, production companies are able to fulfill a necessary prerequisite for achieving an automated production planning and control process – allowing them to remain competitive in the long term.

Do you have any questions on OPC UA or MES – or on how to optimize your production management system using intelligent software, such as MESQ-it? Then please feel free to contact us.

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