University of Twente Student Theses


Fault-tolerance in real time distributed system using the CT Library

Ferdinando, Hany (2004) Fault-tolerance in real time distributed system using the CT Library.

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Abstract:Fault tolerance is more and more important nowadays. The role of computer in industries cannot be neglected. The computers that control machines are often inter-connected via fieldbuses. This can be CAN (Control Area Network), I2C (Inter Integrated Circuit), Spacewire, etc. The goal of this project is to build a fault tolerant distributed system using the CT (Communicating Thread) Library. The CT Library offers an Application Programming Interface (API) for CSP (Communicating Sequential Process) programming in popular programming languages. Fault tolerance itself is too general. Therefore, this project implemented the fault tolerance on communication links in a distributed system. In case of a network failure, the system will switch to the alternative one. The system was implemented on the ADSP-21992 EZ-KIT LITE board from Analog Devices, Inc. This chip has a CAN bus interface for Control Area Network application. This project used the CTC (the CT Library for C). In the application on a specific processor, the CT Library needs addition of hardware dependent part, encapsulated in link driver objects and the context switch mechanism. The link driver part will encapsulate all hardware related operation into specific place in order to maintain portability of the CT Library. Therefore, a programmer can use the same program on different processors by changing its link drivers and context switch. This enables single processor to do parallel processing. This is a kernel function to handle parallel programming in a general-purpose processor. Here, the link driver concept of Hilderink was extended by dividing the link driver object into a Remote Link Driver and a Network Device Driver. The Remote Link Driver is a link driver that provides general purposed methods for communication, while the Network Device Driver is abstract class of all board and fieldbus protocol dependent part of communication. This project used two communication links, i.e. CAN (Control Area Network) and SPORT (Serial PORT). Both need their own link driver. The experiments shows that fault tolerance can be built in the CT Library framework easily by exploiting the hardware dependent part, i.e. the link driver. In a normal operation, the ADSP-21992 EZ-KIT LITE board is driven by 16MHz clock. This makes the CAN module cannot be used in a hard-real time control loop due to its latency. But with a software manipulation, that clock can be raised up to 160MHz and the latency will be decreased.
Item Type:Essay (Master)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:53 electrotechnology
Programme:Electrical Engineering MSc (60353)
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