The difficulty of integrating the Internet of things (IOT) with existing systems is somewhat similar to that of radio and television. Radio and television both use radio waves to transmit signals. Hardware devices at both ends are used to encode and decode the signals, which are converted into audio and image respectively. Although the overall concept is the same, the results are quite different.
This is just like: the equipment produced by one manufacturer uses one communication protocol, and the other system produced by another manufacturer uses different communication protocols. Now we need to configure the two to communicate with each other. Unless there is a special protocol conversion, the two devices will not be able to effectively communicate with each other. This is why connectivity software such as open platform communications (OPC) and data distribution services (DDS) are coming to the stage.
Although the technical details are different, the ultimate goal of OPC and DDS is similar: to connect devices using any protocol through the implementation of standard software interface. This not only simplifies the daily activities of industrial automation companies, which are responsible for supporting these protocols and providing hardware and software for control systems, but also makes it easier for new equipment and instrument companies to integrate systems that existed before the concept of the Internet of things.
An example of the integration of new technologies and existing systems is the concept of geofencing and beacons. Geofence is a software that uses the specified location on the map to track and confirm whether people are in a specific area; similarly, beacon uses hardware integrated with location aware devices to track the distance of people from the beacon. This technology has been widely used in consumer retail applications. When customers are perceived to be near a store or restaurant, they can be sent relevant coupons or notifications. This concept can be applied to safety and emergency alarm systems and other industries.
For example, in industrial facilities, if a geofencing system is configured to track the location of operators, once operators are detected to enter a specific area of the plant, they can alarm the human-machine interface (HMI) in the control room. In an emergency, using this information, it is easy to find the exact location of everyone in the facility. When using mobile devices for data collection, the data can also be integrated with the control system. As an operator, he needs to move in the whole facility. When he moves to different process areas, his equipment can automatically load the correct data to the input screen, so that he can collect readings.
Taking geofence as an example, integrating a new technology in the industrial field requires great efforts, development work and integration testing with a large number of system structures. On the contrary, if the geofence supplier uses OPC or DDS to design the integration of its system and control system, only one or two integration functions need to be developed, and the open interface enables OPC or DDS to communicate with any control system. This can immediately increase the potential market share of the supplier without adding any extra work.
Advantages of integration
Although the principles of OPC and DDS are similar, the technical background is different. OPC is a client server architecture. OPC server communicates with client. The most typical application is industrial control system. Distributed architecture is used between DDS and devices to create point-to-point network to publish information.
OPC has been used in industry for a long time. Different OPC solutions provide a variety of communication protocols and database integration, serial device communication, and integration with network-based devices. On the other hand, the initial development of DDS is derived from the it centered application, which is used to simplify the communication of the whole network; with the expansion of the technology boundary, it is gradually absorbed and applied by the control system architecture.
OPC and DDS act as the middleware between the terminal equipment or the whole system and other systems to standardize the communication configuration and transmit the data to the demander. The choice of the two schemes depends on the installed system and terminal equipment, as well as the integration mode provided by each scheme. As IOT becomes more and more popular in the field of production and manufacturing, it is likely to have both in the final system design.
OPC and DDS are very good tools to improve the overall function of industrial control system (ICS). They can help integrate new equipment into plant facilities, provide more information and process related content, and enable operators and employees to make more intelligent operational decisions.
Main question to ask: what information is most useful? Where does this information come from? What’s the easiest way to get it to where it’s needed? This may mean that OPC and DDS are integrated with non-standard devices by using the combination of different standard protocols in the control system.
One of the main advantages of the Internet of things is its ability to integrate with any number of new technologies, some of which have never been imagined. It makes the new technology easier to integrate with the industrial field, so as to speed up the return on investment of the technology and create more benefits for manufacturers. (by Alex Marcy)