Traditionally, a programmable logic controller (PLC) was simply a black box that sported a proprietary operating system. The PLCs of 25 years ago were basically in the background, and most had to be programmed either on an attached keypad or with a hand-held unit that plugged into the system with proprietary programming methods. Today, there are many more choices of controllers and a push for open systems in information technology (IT) circles is affecting today's programmable automation controllers (PACs), PC-based control software, and embedded controllers. Some vendors promote a Microsoft Windows-based product as a benefit控制工程网版权所有, while others downplay the underlying operating system and talk only about functions. Linux open systems and a handful of real-time operating systems also have their proponents. With such a variety of opinions, we wanted to know: Do operating systems (OSs) matter?
　　"The operating system is not nearly as important as the serviceability of the controller once it gets into the customer's hands; i.e., how easily someone can get under the hood and fix something or troubleshoot a problem," says system integrator Dan Walser with Applied Motion Systems. "Customers in certain industries often prefer a dedicated controller from a local distributor that does not require much in the way of training to swap out partsCONTROL ENGINEERING China版权所有, press a spare CPU into productionwww.cechina.cn, or troubleshoot a logic problem. A Windows-based, open-architecture product that uses readily available parts and a simple software licensing system may be an excellent solution for a highly technical customerCONTROL ENGINEERING China版权所有, yet the kiss of death for a less sophisticated customer."
　　As a system integrator in the packaging industry for more than 25 yearsCONTROL ENGINEERING China版权所有, Stephen Turner of Flexicell Inc. sees two types of user thinking: "Those who want to keep their cost down by using whatever we recommend, and those who will pay extra to match their own standards. Typically, the ones that pay extra for their standard are the larger compa