Compact, multi-tasking controllers yield big digitalization benefits

The term programmable logic controller (PLC) brings about a vision of simple, proprietary device running a dedicated ladder logic program performing basic automation tasks, previously left to hard wired relays. As industry continues to move further into the age of digitalization and Big Data, manufacturers are demanding more of automation controllers, and the role of the PLC has evolved dramatically to meet these demands.  

Today’s controllers are expected to be high performing, robust and modular, and have onboard high-level communications, standard/open connectivity, and simple integration with PC applications and model-based simulation. Some controllers have all these features and can “multi-task,” acting as a PLC, human-machine interface (HMI) and a standard PC in one compact device. 

Integrate PC/PLC functions 

A modern multi-tasking controller combines the functions of a PC-based software controller with visualization (HMI), PC applications (Microsoft Windows or Linux), and central input/output (I/O) connections in one compact device. 

Such controllers, with pre-installed and preconfigured PLC software controller for the control program, which operates independently of Microsoft Windows (doesn’t run on Windows), ensuring high system availability. This enables the controller’s rapid start-up and supports Windows updates and reboot during ongoing operations. Failure of Microsoft Windows does not have an impact on the controller.  

Applications for such optimized controllers include series machine manufacturing and for machines with distributed architectures. Such modular controllers minimize space and can be accommodated in compact control boxes on the machine, improving the cost-performance ratio. Visualization can be realized via an industrial flat panel connected through the graphics interface, optionally with multitouch functionality. Since the PC is built in, no separate PCs are required. For commissioning, mouse and keyboard can be connected via standard onboard USB interfaces. At the same time, the gigabit Ethernet interfaces support high-performance connection to higher-level networks. 

Rugged applications 

Car charging stations are an example of a rugged, industrial-type application requiring modern controller architecture for four reasons. 

1. Compact size – charging station has very limited space inside, requiring a compact, multi-tasking device. 
2. PC-based controller independent of Microsoft Windows – It has to run 24/7 and cannot shut down during an operating software update or failure. 
3. Flexibility – High–level modular programming structures allowed this application to be easy adaptable to three charging standards. 
4. Easy integration of Microsoft Windows applications – No separate PC is needed for PC applications and HMI, only a multi-tasking PLC and a touch panel. 

Many applications may benefit from a multi-tasking controller architecture. Industrial plant and assembly line applications can share the same requirements. Compact, multi-tasking controllers are also expected to include standard functionality like built in safety, integrated security, built in diagnostics, and high-level motion control in one package.   

Jim Wilmot, Factory Automation Marketing Manager at Siemens Industry Inc. Edited by Mark T. Hoske, content manager, Control Engineering, CFE Media, mhoske@cfemedia.com. 

KEYWORDS: Programmable logic controller, PC, HMI 

Integrated PLC-PC-HMIs help digitalization. 

Rugged applications benefit from updated control architectures. 

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How will more advanced PLCs help your applications? 

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