Thin Clients Can Eliminate Software Issues

April 7, 2010
Set the Server for HMI and SCADA: Energy and Space Are No Longer Issues With Thin-Client Technology
By Jeremy Pollard, CET

Computers consume piles of joules that cost money to use and money to generate and money to maintain. Thin is in; fat is out.

Virtualization and terminal services (TS) are typically the domain of all IT departments and require a software "server." Thus, the IT group is involved. And we all know what happens when servers, IT and control guys get in the same room—that's when the fight starts. So can we do it ourselves and use thin-client technology for any of our plant floor and vertical applications? You bet.

You can set up your own server—any computer at all—which can run VMware, Sun or Microsoft virtualization services, Microsoft TS or even VNC connected services.

This means all applications are installed and run from the server, and the clients just need run software such as VNC, VMware client or RDP protocol to connect to the server to use the server-based applications. The applications could range from Open Office to HMI and SCADA software.

You could use an old computer to run client software such as Remote Desktop protocol (RDP) to connect to the servers, but that would defeat some of the purpose of going thin.

A thin client typically is a device based in firmware with no spinning hard drives, a small footprint, and typically running Windows CE and requiring much less energy. I use thin clients from Esprit Technology, and its thin clients use 1.2 A at 12 Vdc max. A Dell server I have here uses more than 3 A at 120 Vac, and a workstation is just less than 3 A. There is even an iPhone app to run RDP if you want.

There are many reasons to have a different approach to industrial-use computing. And there are two very distinct components for the solution—hardware and software. The hardware is easy.

Server side software varies in initial cost, price per user, installation requirements and performance statistics. Reasons for using one server platform over another can be based on the number of users and the applications. Certain industrial software cannot run in a distributed environment.

Depending on the platform, you save energy, development and runtime costs and, of course, hardware costs.
There is typically no performance penalty when using a thin-client environment, and there's no limit to the number of users. However, depending on the server hardware, applications and connectivity, a load-balancing system might be required.

All of these solutions scream "bottom line" for using thin clients. Cost, less maintenance and ease of application support are just a few of the benefits. I use thin clients with an XP-based TS server for HMI in a distribution center. I can tell you that setup and implementation are a dream.

Security is no longer a factory floor issue. It migrates to the server. If a component fails, you replace it, download a configuration file for it and you're done.

This is for cases in which the connected network is Ethernet. While the control network and the factory network could be different, routers can handle vertical apps easily. This means any user can access any application through the configuration on the server and not the client. This central management is key, in my opinion.

You can handle almost any application using this distributed architecture. I think you should not use devices such as dedicated HMI terminals that use a proprietary operating system, due to the hardware cost and application maintenance, development and support. If you use the device for anything more than pushbutton replacement, I would use a Windows-embedded OS device or equivalent.

If you use more than one interface, the cost of using two thin clients and a server will surprise you, and the development of the application will be simple.

The key, though, is the use of an embedded thin client. We are returning to the way things were with terminals—not as smart as a desktop, but much more secure, and it does everything we need. That's what's important.

There are various software platforms you can use, such as Visual Studio, VB.NET, C#, Inductive Automations' Ignition, RSView, Wonderware's InTouch, InduSoft and many others. Which one is best in this environment is a matter of opinion, and of course I always have one of those. But you'll have to wait for the next column. Have I got a deal for you.