Communication upgrade INTRO: OPC stands for effortless
communication in the manufacturing industry

BLURB: One doesn’t need to know about the other’s communications protocol or the internal data organization. Thus, there is no limitation for the number of connections made on the OPC

In today’s times, connectivity makes the world go round. For the industry, it is the Open Connectivity Standard (OPC) that is the answer to most communication woes. In the automation industry specifically, the OPC stands head and shoulders above other conventional communication protocols. With its open standard specs, interoperability is, perhaps, one of its biggest advantages. Let’s understand the basics of OPC first. It is basically a series of standards specifications, which initially resulted from several automation suppliers working with Microsoft on the subject.

The specifications defined a standardized set of objects, interfaces and processes that can be used in process control and automation applications in the manufacturing industry. Simply put, it is a way to communicate between devices, controllers and applications while doing away with the connectivity problems. It bridges the gap between a data source and a data sink, and makes it possible for them to exchange data, under nearly any circumstance. And while the data source and data sink can communicate with each other via the OPC, their own protocols aren’t replaced by the OPC.

Actually, these protocols communicate with only one of the two OPC components, while the OPC components share information and close the loop. And how was it before OPC made life simpler? Not easy, one must say. Let’s take the proprietary protocols, for instance. While these protocols helped products across a specific product line to communicate with each other, you needed special customer drivers for communicating with products from other vendors. Often, even different products from the same vendor needed different connectors. The advent of OPC made it redundant to know about data source communication and how it works.

The custom drivers needed to communicate between two different endpoints had their own limitations. Specific protocols needed to be drawn up for the same and if a custom driver for the two specific endpoints was unavailable, data communication couldn’t happen. With the help of OPC, there is no need for customer drivers between two applications and/or data source.

Custom drivers often made things complex. For, between every endpoint there had to be several drivers. Multiple installations and configurations of the same driver on each computer were needed for the same HMI. Obviously, the maintenance of all the paraphernalia added to the complexities. Then, the same information when needed by different applications would increase the amount of traffic, putting a lot of strain on the controllers. On the other hand, the use of one OPC connector for one kind of data source does not need additional custom drivers. The traffic, too, would be significantly low with an OPC connector. With a variety of products hitting the market at rapid speed, vendors stop supporting the older ones. As a result, a newer version of HMI might again require a new set of device drivers that don’t support communication with devices that were supported by the earlier HMI version. On the other hand, once the OPC connector is configured for a particular legacy system, any OPC-enabled application can work.

All in all, where OPC works and other communications fail is because the OPC abstracts the implementation details about the data source and data sink. This basically means that one doesn’t need to know about the other’s communications protocol or the internal data organization. The result is that there is no limitation for the number of connections made on the OPC. Also, OPC supports the most commonly used types of automation data that are transferred between devices and controllers, namely, real-time data, alarm and event data, and historical data. This, and the ease of use, has made OPC so common that there is an OPC connector for nearly every modern and legacy device available in the market.

Also, data sources that are OPC-enabled can be exchanged and upgraded without having to update the drivers that are used by each application (the data sink), that is communicating with the data source with the help of OPC. The OPC server for the data source is upgraded and you are good to go. At the same time, users have the freedom to choose devices, controllers and applications that suit their needs the best, without having to worry about the vendors and if they will be able to communicate with each other.

 

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