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Linux: A Worthy OS for Real Applications

Once regarded as a tool for hackers, Linux has found use in mainstream engineering applications. Linux devotees fervently promote their OS, but what is the real "signal-to-noise" ratio?

David Marsh, Contributing Technical Editor -- Test & Measurement World, 10/15/1998 2:00:00 AM

After using Windows 3.1 applications, your company decides to skip Windows 95 and 98 and move to Windows NT. Such a move may make sense, because if you’re going to change to a new operating system (OS) you might just as well choose one that appears to cause the least migration pain. Microsoft asserts that NT is the professional’s choice, and Windows 98 will be the last of its genre. Future Microsoft OS releases will likely be derivatives of NT.

Unfortunately, you may get frustrated with repeated instances of NT’s infamous "blue screen of death" syndrome in which, for some reason, the system just doesn’t work any more. You can’t progress beyond a screen full of messages that demand expert knowledge to decipher. Eventually, you realize that many problems arise from some insignificant change in the local environment—like trying to load new drivers for some "unusual" hardware device, such as a data-acquisition board.

You have an alternative to Windows NT. It’s called Linux, and you can get it for little or no money. Linux is a free Unix distribution that you can download over the Internet. Like Unix, Linux provides a true multiuser, protected-mode, multitasking OS that can run on PCs and on computers based on Alpha and SPARC microprocessors, among others.

Perhaps you remain unconvinced. Is it really practical, you ask, to dismiss the Windows environment and use another OS to control instruments?

First, Look to the Web
You can start investigating Linux by doing a search on the Internet. Linux devotees adhere to a creed of sharing information freely, so you’re certain to find assistance with virtually any Linux-related question. 

Many Linux users are Unix-wise scientists and engineers who use Linux-based systems for instrument-control, data-acquisition, and data-analysis tasks. If you fall into this category, look for test-and-measurement-related Linux information at www.llp.fu-berlin.de, the Linux Lab Project at the Free University of Berlin. Here, you’ll find everything from data-analysis software and drivers for IEEE 488 interface cards to kernel patches, all freely available for downloading. The site also provides links to commercial hardware and software suppliers, including familiar companies such as ComputerBoards, Hewlett-Packard, IOtech, Motorola, National Instruments, and Texas Instruments.

Another Web site that provides comprehensive lists of sources and links is Linux Online
(www.linux.org/apps/index.html ). The site lists many commercial and freeware packages, as well as basic information about Linux.

Why Move to Linux?
Why have many engineers moved to Linux? Because of the freedom it provides. Many engineers think that IT departments drive managers to adopt the NT OS because they feel safe under Microsoft’s umbrella. But engineers often dislike Microsoft’s and NT’s "stifling" influence and prefer Linux’s open-systems approach. In more practical terms—after several years of haphazard development—the Linux distributions by Caldera, Debian, Red Hat, and Walnut Creek now offer users a stabilized OS that can justify commercial consideration.

Here are some common reasons that devotees give for moving to Linux:

• Stability. Linux just runs and runs without system crashes, reboots, or any undue attention, while some engineers perceive Windows NT as being unreliable.

• Integrity. The open systems approach encourages the best from the programmers and users best placed to contribute to OS development.

• Versatility. Because Linux source code is freely available, you can customize Linux to suit specific hardware resources. There are a huge number of Unix utilities developed over decades that will run under Linux, and most are free.

• Support. Informal but matchless support through Web newsgroups and forums and e-mail communication with like-minded engineers.

• Choice. Linux OS derivatives coexist gracefully to the degree that you can specify another company’s distribution if you don’t like the one you have.

• Economy. Linux costs little or no money.

Some of the very things engineers perceive as assets, managers see as liabilities; for example, accountability and support. After all, if the software is free, who takes responsibility for it? And then there’s the customizing issue—how can an IT manager track maverick Linux users? Software publishers regard Linux’s openness as its major problem. They need secure licenses to protect their investments.

Most Linux distributions run some form of X-Windows graphical user interface (GUI) on top of a multiplicity of hardware. Software developers worry that they will have to spend time attempting to support a myriad of end-user configurations, especially because users have access to the OS source code. Despite these concerns, there’s growing mainstream commercial interest in Linux. Corel and Informix recently announced they will port some of their commercial software to Linux.

Linux Controls Instruments
Linux finds increasing use in instrument-control applications. Users in the high-energy physics world demonstrate what the OS can achieve in large-scale deployments (see hepwww.ph.qmw.ac.uk/HEPpc/). Scientists at Fermilab (Batavia, IL) use Linux-based PCs to control instruments that range from CAMAC crates to VMEbus-based instruments (www.fnal.gov). Fermilab’s Don Holmgren says, "There has been a good deal of work at Fermilab on Linux-to-VME interfacing, specifically, the implementation of the ‘Vision’ standard in a product called ‘Fision.’ Fision is basically a client-server package. A client can contact a server running a bus-master node over a network. The Fision API lets the client manipulate the cards on the bus as if they were local."

One of the more interesting Linux applications is in clusters of PCs that handle the vast amounts of data that result from experiments for detecting quarks. Holmgren says, "Our main use for Linux is for off-line data analysis. We’ve traditionally operated large clusters of Unix workstations for data reduction. Earlier this year, we had 400 workstations for this purpose.

"So, we got started on Linux because it ran on the most cost-effective hardware for our computations. All of our analysis code is written for Unix, so the fact that Linux is such a ‘pure’ Unix was a great advantage. Nearly all the code ports from our other computer systems have been easy. Because we can examine the source code in detail and make modifications as necessary, Linux offers a great advantage. Also, we’ve instrumented Linux to let us ‘watch’ code execution. This ability helps us understand the performance constraints of hardware so we can deliver the lowest-cost system that still meets our requirements."

If you search the Web, you’ll find other reports of Linux-based data-acquisition and instrumentation systems, such as NASA WFF’s airborne laser system (see aol11.wff.nasa.gov/aol-III.2/datasystem/). The laser system comprises a 166-MHz Pentium PC coupled to two LeCroy Model 9354 DSOs through a National Instruments’ AT-GPIB interface card. A global positioning system receiver and an infrared radiometer communicate with the PC host over RS-232C lines (see Fig 1).

Figure 1. A computer system based on Linux can control sophisticated measurement systems. In this example, a PC operates two oscilloscopes, a radiometer, and a GPS receiver as a part of a sea-monitoring experiment.

Try Linux for Yourself
Despite enthusiastic reports, there’s no substitute for trying Linux for yourself. If you’re tempted, first check out whether Linux will run on your hardware and whether it will run with added hardware such as a CD-ROM drive, a display card, and so on. You’ll find a wealth of information at sunsite.unc.edu/pub/Linux/docs/HARDWARE. If you’re starting from scratch, you may have an advantage over people who must use existing computers. You can build a machine using components such as video, Ethernet, and SCSI cards that have Linux drivers. Otherwise, there’s no guarantee that Linux will immediately support the components of your system. In general, you’ll need a Pentium-class processor with at least 32 Mbytes of RAM, a floppy drive, a CD-ROM drive, and up to 1 Gbyte of free hard-disk space.

When you’re through installing and trying Linux, you’ll have a better idea of whether you should pursue Linux for your applications. You’ll feel at home with Linux if you already have a good knowledge of Unix, but there is a generation of users who have never done more than use a mouse to point and click on menus. Unfortunately, Linux isn’t easy to use. It has a steep learning curve for people who aren’t familiar with Unix.

While Linux’s X-Windows environment helps, you still need to know how to use a command line to type in commands and information. Despite criticism, Microsoft has forced consistency into applications. Control keys, buttons, and icons respond fairly consistently throughout the Windows world. Using the command line won’t deter a Linux zealot, but it will scare mainstream PC users.

Get the Drivers
If you plan to develop an instrumentation system under Linux, make sure you can get the drivers and other application software you need to develop and support your applications. You’ll find drivers for National Instruments IEEE 488 cards at the Linux Lab Web site, along with a five-page (2-Mbyte) document that describes the driver architecture and its capabilities.

You’ll also find tools for developing your own drivers, including drivers for CANbus and PCI-bus hardware. And although you won’t find a Linux version of Microsoft Office, you can choose from a host of spreadsheets, data-analysis programs, text processors, and report generators for Linux.

Red Hat Software’s Robert Hart concedes that Linux has a steep learning curve. In the commercial environment, Red Hat Linux is aimed at the server and at engineers’ desktops. The company plans to offer Linux for more general use in 1999, using the GNOME (GNU Network Object Modeling Environment) project as a basis for its GUI. (You can find more information about progress on building a complete, user-friendly Linux desktop at www.gnome.org.)

There’s no doubt that Linux provides a stable networking and application development OS for all classes of technical applications. But you must decide for yourself if Linux’s advantages outweigh its disadvantages. As Jon Powell, senior scientist at ViewLogic Systems says, "The main things that engineers and scientists like about Unix and Linux are that it lets you do what you want, and if something goes wrong, you can dig in and fix it." T&MW

David Marshis a freelance writer and project engineer with more than 20 years of experience in test and measurement and the general electronics industry. He is a contributing technical editor for Test & Measurement Europe and EDN Europe magazines.

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