Combining the ruggedness of PLCs and the ‘limitless potential’ of PCs could be the ideal solution for industry, says Gary Provis
Historically, the traditional PC solution to control machines and processes has not been deemed suitable for the harsh, often dirty and frequently challenging industrial environments found in process and manufacturing scenarios. Temperature extremes and a lack of robustness meant many companies would not consider the PC as the solution for their automation control needs. Add to this an underlying worry about PC software issues, such as loading tasks and the potential for failure, and it is clear why many have opted for the seemingly more robust and apparently safer PLC route.
Conversely, while the tough nature of PLC hardware was generally viewed as being able to stand up to difficult working surroundings, some also considered the PLC option as potentially lacking in some areas, such as the range of reporting functionality that is second nature for the PC.
Against this background, it is also apparent that the market drivers and demands when considering which route to take are rapidly evolving. Machines and processes are becoming faster, applications are becoming ever more complex and the machine concepts now being delivered are becoming more flexible in nature. This changing landscape is leading to the need to satisfy a number of issues. These range from the need for increased memory and processing performance, increased integration of Ethernet into controllers, seeking automation solutions in one device, as well as being mindful of the need to integrate safety technology.
Two alternatives have traditionally presented themselves. The classic PLC approach has taken up the baton and is now offering more powerful performance and a tangible increase in the number of integral functions. PCs and operating systems, on the other hand, have fought back with improved performance in harsher industrial environments and the integration of many tasks onto a single PC.
The distinguishing features of the PLC ensure that it has its advocates. Such a solution can offer fault-tolerant and fail-safe technology and is designed and built for maximum ruggedness. It is modular and scalable, offering a degree of flexibility to users. Importantly, areas such as spare-part availability for up to 10 years and relatively simple maintenance can make the PLC a safe, less risky option to take.
PC-based controllers, on the other hand, offer the high-performance characteristics that are now more commonly required in industrial settings. They too offer scalability, but with the benefits of open communication mechanisms to allow complete integration within the PC world. They also offer simple and straightforward connection to databases for information gathering and reporting requirements.
However, another option exists that in many ways offers the best of both worlds, by combining the ruggedness of the PLC with the limitless potential of the PC to provide the type of all-in-one solution that should cater for any controller requirement. Embedded automation is a concept that essentially provides a ‘PC within a PLC’ and promotes the best attributes of each approach into an integrated single solution. It can offer the standard PC interfaces that users of the PC have come to expect, combined with the working ruggedness of the traditional PLC solution, making it suitable for withstanding even the harshest of working environments.
Allied to the ability of an embedded automation solution to function consistently in such circumstances, users benefit from the flexibility built into the open PC platforms, which allows far greater flexibility and performance potential than could be expected from just the PLC platform alone.
Finally, embedded automation solutions have the added advantage of pre-installed automation software, which makes it easy and straightforward to implement without the concerns linked to software installation at later dates.
The combination lets the user enjoy the best of both worlds: the single-box hardware is compact, maintenance free, modular and open — incorporating Ethernet, USB and MMC interfaces; it has the new, tougher, stable and open characteristics of pre-installed software; and it provides options for: data retention, both virus and maloperation protection, built-in safety procedures, embedded preconfigured Windows environments with optimised automation tasks, and the integration of standard PC applications.
The embedded automation solution has within it many flexible options that can cater for individual circumstances and requirements. These can range from design of the solution to installation and service needs. Indeed, customers that want control functions in addition to visualisation, and that value long-term availability of applications — through to the end user that requires visualisation, and the controller that values scalability, proven performance in the most demanding of conditions and the openness to collate, monitor and report — will appreciate the value delivered by the embedded-automation approach.
In summary, embedded automation is the powerful combination of the classic PLC and PC worlds. On their own, each has plenty to offer. Put their best characteristics together and you have a compelling, engaging and high-performance automated control solution that is worth serious consideration.
Gary Provis is product manager — industrial automation systems — for Siemens Industry Automation