Linux in Embedded Industrial Applications: A Case Study

In order to allow the acquisition of diagnostic data from an existing industrial plant which was not designed for the purpose, a protocol converter gateway has been built by using an industrial PC running Linux.
Conclusions

We have shown how the use of Linux can solve a typical problem of data acquisition in an industrial environment. Actually, we were able to build a system which can do something useful with 32MB of RAM and as little as 8MB of disk space, but the most noteworthy characteristic of the system is its robustness.

Disk access is limited to read-only at boot time; the run-time file system is supported by RAM disk. This means that restarting after a power failure will never require a file system check, which could otherwise prevent the boot process from proceeding. Moreover, because all the system files stay on a read-only device, it is most unlikely that they are inadvertently tampered with by anybody. Finally, in case of a program crash, Linux provides the capability to restart the processes.

The native support of the compressed kernel and root images was also very valuable because it allowed us to keep the entire system very small.

email: lfini@arcetri.astro.it

Luca Fini (lfini@arcetri.astro.it) has been with the Osservatorio di Arcetri for 20 years where he has worked as software developer and system manager of a LAN with more than 100 computers running UNIX, Linux, Windows 95/98/NT, MacOS, and more. He also deals with control system design and development for both astronomical instrumentation and, occasionally as an independent consultant, in the industrial field.

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