You know what a PLC is. You’ve been using digital controllers in your applications for years. Very likely, you know what a PAC is. This term encompasses PLCs being produced that offer a more advanced range of features. A controller can be defined as a PAC if it includes features such as increased flexibility in programming such as C/C++, improved interoperability using standard protocols, a modular open-architecture design, and features and functionality that enable operation in multiple domains such as process, discrete and motion control. A majority of PLCs being put into use today are, if fact, PACs.
You’ve also heard a lot about edge controllers, the new devices that are offered as a solution to so many automation problems today. But do you know what an edge controller really is? In a recent issue of Controls, Drives & Automation, Emerson experts discuss the essentials that define edge control.
Because edge control technology is new, people will tend to define it in various ways, but what way is correct? Should a device be considered an edge controller because it provides Ethernet communication, offers a simple web server on a PLC, or has OPC UA capability on a PAC? If you added the right software to a laptop computer or a mobile phone, could you regard it as an edge controller? How do you prioritize deterministic PLC-type control compared with general-purpose computing aspects?
In fact, edge controllers have very specific definitions. An edge controller is first and foremost an industrial automation controller that must provide real-time determinism to control the machine or process. A true edge controller should be designed to safely integrate this deterministic control functionality with non-deterministic edge functions in a single platform, so that neither can inadvertently impact the performance of the other. This will ideally be achieved with two independent operating systems (OS) – a real-time OS (RTOS) for deterministic control, and a general-purpose OS (GPOS) such as Linux for edge applications.
There are a number of other capabilities that define an edge controller. To review these, check out this article.