This is an excerpt from the January/February 2014 issue of InTech magazine by Jeff Payne, product manager of automation controllers and interface software at AutomationDirect. To read the full article, please see the link at the bottom of this post.
Faster speeds, lower costs, and greater connectivity are essential to the success of all businesses, including manufacturing. With the introduction of lean manufacturing, Six Sigma, and other continuous improvement strategies, operations must become more flexible, easier to manage, and less expensive.
To achieve these goals, businesses demand user-friendly human-machine interface (HMI) graphics, the ability to drill down quickly for alarms, overall equipment effectiveness dashboards, and more. In addition to having reliable information at their employees' fingertips, companies also want better remote HMI access from a variety of devices. Finally, they want more intuitive interfaces to reduce training costs and improve operator performance.
Fortunately, there are HMI packages available that can fulfill all these requirements. The latest HMI software solutions shorten development time, offer better remote access, and have more intuitive interfaces to reduce the learning curve for operators and other users. Overall, these enhancements facilitate a more mobile and productive workforce while reducing training and equipment costs
Is a PC the best choice?
When selecting an HMI, the first decision is whether or not it will be based in a PC. PC-based HMIs have the best performance, the most features, and the easiest connectivity-but also have the most expensive software licensing costs. HMIs that are not PC-based typically run on embedded operating systems. These embedded HMIs are much less expensive than PC-based HMIs in terms of software licensing costs, but are also less capable in performance and feature richness.
With respect to hardware, costs depend on whether the HMI will be in the controlled environment of a control room or an office, or on the plant floor. In a controlled environment, a PC is less expensive than a similarly sized embedded HMI. But on the plant floor, an embedded HMI is much less expensive than an industrial PC. For many applications, connectivity and remote access will drive the PC versus embedded decision.
Mobility is no longer just an option
No one can now imagine a successful company that does not have remote access to business systems; the same will soon be true for automation. With just five operators being hired for every 10 that retire, mobility is essential for increasing productivity. Employees can no longer spend the entire day in the control room or one area of the plant, thus HMI remote-access capabilities are mission critical.
Mobility is often provided through wireless and cellular networks. Although security is a concern, wireless networks are rapidly becoming an accepted medium of communication in industrial environments. Lower installation and maintenance costs along with improved security have made wireless attractive to automation companies. Wi-Fi and Bluetooth are affordable, fast, and easy to use. And thanks to the evolution of encryption and the IEEE.802.11X-based Extensible Authentication Protocol, user devices must be identified to gain access to the network. Cellular networks are an attractive alternative to wireless in many cases, particularly as speeds are increasing while costs decline.
What kind of remote access is best?
When developing remote-access applications, the type of user and his or her requirements must be considered, along with costs. Evaluating these and other factors will determine the appropriate method of access from the listed options.
Note that most companies will use multiple methods of remote access, mixing and matching depending on the specific needs of the particular user, on the costs involved, and on the technical capabilities of the organization.
Most every PC-based HMI will support all four remote-access options, whereas most embedded HMIs will only support web browser and app access. Embedded HMIs are meant to stand alone for the most part, whereas PC-based HMIs are often part of a networked system of PCs and thin clients.
Remote access via a PC has the best remote user experience. PC remote access is very low in hardware cost if the user already has a PC and is using it for other purposes. But networking a remote PC can be expensive, and software licensing costs are high. If the remote-access PC needs to be mounted on the plant floor, costs will be very high.
A better alternative for plant floor remote access is a thin client, which has nearly all the capabilities of a PC at a much lower cost, both in terms of software licensing and especially hardware. Not only is a thin client less expensive to purchase, it is also much less expensive to mount on the plant floor. It will have much less processing power than a PC, and hence generate less heat. Thin clients are also much less expensive to maintain than PCs, as most all software is installed and maintained at the PC-based server as opposed to on the thin client.
Whether the HMI is PC-based or embedded, browser and app access are two other remote-access options that should be considered and evaluated.
About the Author
Jeff Payne has worked in industrial automation for more than 25 years; he is the product manager of automation controllers and interface software at AutomationDirect.
