Is it Time for Linux, Yet?
A reader writes, "Your magazine discussed Linux as a plant-floor operating system alternative a few years ago. The opinion then was "not yet." We're seeing it a bit more now on various vendor web sites. We have to think about getting away from unsupported NT, but the question for us remains the same. Would Linux offer us any real advantages in operating reliability and troubleshooting at customer sites? Are we on are own for developing device drivers? "
-- From Control Design
Linux Needs a Big Brother
Linux is currently offering significant advantages in reliability and capability through its implementations in embedded systems, thin clients, and elsewhere. The mitigating factor is the lack of Linux versions from major software manufacturers. If just one of them produces a Linux version then integrators could make a serious attempt to move Linux into the foreground for SCADA, HMI and PC-based control systems. This won't happen until the manufacturers hear the requests coming from customers, so talk it up!
Michael G. Meade, Partner
Integrated Automation Solutions, Sparks, Md.
We Think It's, Ready
In recent years Linux has matured into a reliable and productive operating system in today's industrial controls industry. It has many features that meet modern control requirements.
One of its more important features is the stability of the operating system and the security that is integrated with it. Linux isolates the potential threats from the system files that run the required function. Constant refinements to both the operating system and the application software provide updates faster than Windows products. Linux also gives one the ability to configure the system to run minimal-amount processes, as well as the device driver needed to create a real-time operating system.
Our new industrial PC, packaged with Linux I/O modules are accessed directly without the need to append the data with another communication protocol when complex data processing is needed. This decreases the overall scan time.
Paul Reszka, Product Engineer
Wago Corp., Germantown, Wis.
Not Yet? Not So!
One of the most complicated control systems in the world at the U.S. Postal Service has been and continues to be run on innovative technology with Linux. If you search the keywords "USPS Linux image," you'll get lots of hits.
Linux system can be broadly categorized as servers, workstations and embedded systems. Embedded systems is an area where Linux is most dominant, to the point of devastating all commercial real-time operating systems (RTOS), in competition. Linux has millions of the world's young and brightest minds fanatically devoted to the paradigm shift of open-source computing.
Encrusted RTOS vendors have lashed out at embedded Linux and its rapid ascension to become the dominant RTOS in the U.S. Department of Defense. You are hard-pressed to find an industrial product, in any field that generates any sort of revenue, which does not have competitors using embedded Linux in one of its many forms. It runs on everything from 8/16-bit micros and DSPs to IBM mainframes and everything else in the middle.
Most likely, many of your readers are using embedded devices such as the myriad of Modbus to Modbus TCP protocol translators that are built on embedded Linux.
So why has embedded Linux not become dominant in the daily lives of the average controls technician, programmer or engineer? If a controls vendor has been successful building proprietary hardware, firmware (the embedded software on the microprocessor that you cannot modify) protocols and software, then it stands to lose market share with the deployment of embedded Linux into the controls industry.
Remember also that of the companies that build industrial products, many do not want the user to know there is embedded Linux inside, because customers might get a wild idea and consider building their own solutions rather than purchasing it from the big names in the industry.
If the majority of industry professionals had any real exposure to the excitement of TCP/IP and embedded Linux to solve real-world problems, there would be a changing of the guard overnight. Momentum and young engineers, programmers and technicians, many of whom have tasted the energy of embedded Linux, will change the face of controls as we know it today. Here are but a few of the reasons:
Advanced tools for developing complex software.
Software (PLC code) portability.
Secure systems via encryption and myriad secure semantics not possible with the existing proprietary protocols.
Same core kernel technology on your server, your workstation and your controls system.
Fully deterministic systems,not many exist currently on traditional PLCs.
Scalability, The Linux 2.6.x kernel now supports distributed processing on heterogeneous processors. This means that a processor in a PLC, if it has the right firmware/kernel, could use the excess processsing capabilities on another PLC.
Linux can run everything from a 16-bit micro to an IBM mainframe. The hottest area for Linux is embedded in microcontrollers and microprocessors. Embedded RTOS vendors are crying foul, but the challenge is no match at all.
Embedded Linux leads to embedded products. The controls industry is but one industry built on ancient and often decrepit proprietary technology. When the Linux tsunami finally hits, your average, older controls engineer will be swept away, just like the guys that used to run all of those proprietary printing presses at newspapers.
Finally, here are links to web sites and stories that explain how Linux has progressed in the controls area:
James Horton, MSCS, PE
Linear Motors or Pneumatic Slides?
"We make packaging equipment and use pneumatic linear slides. They've been pretty accurate and we know how to support them. One of our new engineers is all about linear motors and feels we'll have a big improvement in accuracy and reliability, simpler maintenance and increased machine uptime if we redesign. What do you think?"
Send us your comments, suggestions, or solutions for these problems. We'll present them in the September 2004 issue. Send visuals, too,a sketch is fine. E-mail us at CDTheAnswer@putman.net or mail to The Answer to Your Problems, CONTROL DESIGN, 555 W. Pierce Rd., Suite 301, Itasca, IL 60143. You can also fax to 630/467-1124. Please include your company, location, and title in the response. Have a problem you'd like to pose to the readers? Send it along, too.