Real-time application interface (RTAI) is a real-time extension for the

Linux kernel The Linux kernel is a free and open-source, monolithic, modular, multitasking, Unix-like operating system kernel. It was originally authored in 1991 by Linus Torvalds for his i386-based PC, and it was soon adopted as the kernel for the GNU ...

, which lets users write applications with strict timing constraints for Linux. Like Linux itself the RTAI software is a community effort. RTAI provides deterministic response to interrupts,

POSIX The Portable Operating System Interface (POSIX) is a family of standards specified by the IEEE Computer Society for maintaining compatibility between operating systems. POSIX defines both the system- and user-level application programming inte ...

-compliant and native RTAI real-time tasks. RTAI supports several architectures, including

IA-32 IA-32 (short for "Intel Architecture, 32-bit", commonly called i386) is the 32-bit version of the x86 instruction set architecture, designed by Intel and first implemented in the 80386 microprocessor in 1985. IA-32 is the first incarnation of ...

(with and without

FPU FPU may stand for: Universities * Florida Polytechnic University, in Lakeland, Florida, United States * Franklin Pierce University, in New Hampshire, United States * Fresno Pacific University, in California, United States * Fukui Prefectural Univ ...

and TSC),

x86-64 x86-64 (also known as x64, x86_64, AMD64, and Intel 64) is a 64-bit version of the x86 instruction set, first released in 1999. It introduced two new modes of operation, 64-bit mode and compatibility mode, along with a new 4-level paging ...

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, ARM (

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and

ARM7 ARM7 is a group of 32-bit RISC ARM processor cores licensed by ARM Holdings for microcontroller use. The ARM7 core family consists of ARM700, ARM710, ARM7DI, ARM710a, ARM720T, ARM740T, ARM710T, ARM7TDMI, ARM7TDMI-S, ARM7EJ-S. The ARM7TDM ...

: clps711x-family,

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EP7xxx, CS89712, PXA25x), and MIPS. RTAI consists mainly of two parts: an Adeos-based patch to the Linux kernel which introduces a hardware abstraction layer, and a broad variety of services which make lives of real-time programmers easier. RTAI versions over 3.0 use an Adeos kernel patch, slightly modified in the x86 architecture case, providing additional abstraction and much lessened dependencies on the "patched" operating system. Adeos is a kernel patch comprising an Interrupt Pipeline where different operating system domains register interrupt handlers. This way, RTAI can transparently take over interrupts while leaving the processing of all others to Linux. Use of Adeos also frees RTAI from

patent A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an sufficiency of disclosure, enabling disclo ...

restrictions caused by RTLinux project.

RTAI-XML

RTAI-XML is a server component of RTAI, implementing a service-oriented way to design and develop real-time (RT) control applications. This project was born to fulfill the needs of a university group, mainly focused to have a flexible platform for learning control systems design, allowing the students to test their programs remotely, over the Internet. Leaving the first wishful thinking and going to the real implementation gave rise to the alpha version of RTAI-XML, that showed the potential impact of the basic idea of a net separation of ''hard'' and ''soft'' real-time tasks in the programmation logic. What was necessary to assure that students could not crash the RT process, is now becoming a new RTAI paradigm. RTAI-XML consists of a server component waiting for incoming calls on a box where a real-time process, the Target, is running (or ready to). A generic client program, the Host, can reach the server through the TCP/IP network, using a standard protocol based on

XML Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. ...

, and hence interact with the Target, in order to monitor the status of the RT process, to see the signals collected (or generated) by the system and also to fetch and change the RT parameters (for example, the gains of a PID feedback ring). In other words, RTAI-XML provides a simple way towards

remoting In distributed computing, a remote procedure call (RPC) is when a computer program causes a procedure (subroutine) to execute in a different address space (commonly on another computer on a shared network), which is coded as if it were a normal (l ...

of control applications, adding flexibility to the RTAI project, without losing the key features of an open and standard implementation. The RTAI-XML section of this site presents the details of the implementation. The general architecture is revised, in order to focus the three key components, the Server, the ''Server-Target'' interface and the ''Server-Host'' communication. The Applications section contains some examples of control systems based on RTAI-XML and the References section contains hints and links for further readings on this topic.

References

External links

*
Univ. di Padova - RTAI / Xenomai presentation

RTAI-XML official website
{{Linux Linux kernel Real-time operating systems

RTAI-XML

See also

References

External links