| WP 4 Real-time for Embedded Automation Systems | ||||||||||||||||||||||||||||
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Differently to office applications, the industrial automation systems require real time aspects for automation applications.
The specific needs for e.g. time critical automation applications are not covered by the current office based technologies. Besides, legacy systems do not provide means for overall networking. A research, identification and implementation of feasible technologies and standards as a base of real time technologies for industry environment was in the focus of this work package. A real time classification in conjunction with automation applications has been performed. The main attention has been paid to inter-LAN and WAN RT communication (over public networks). PROFINET has been selected as the most suitable technology in VAN. Real-time over UDP (using PROFINET) is to be stressed. Redundancy is as well in scope. IRT communication has not been considered, neither in inter-LAN nor in WAN. Only RT communication has been taken into account (Classes defined by PROFINET).  Achievements and Results Investigation has shown that current real-time solutions are restricted to work in a single LAN (Local Area Network). A classification grid has been worked out showing three classes of real-time communication in three different environments (single LAN, Inter-LAN and over public networks) with their corresponding applications. Single LAN was not in WP4 focus, because several solutions already exist. WP4 recognized a potential in delivering real-time inter-LAN communication (real-time between different LAN segments) based on the trend screening and customer requirements on the one hand, and missing industrial solution on the other hand. Sources of decreased determinism were identified at two positions to be handled by different means:
VLAN tagging is natively supported method of IEC 61158 Type 10 for real-time communication. However, extensions had to be provided to support DSCP coding for factory automation. The semantic mapping of traffic classes to DSCP has been developed in cooperation with WP7. DSCP tagging is supported by RToUDP. Moreover, for tunnelled communication the OpenVPN software was extended to provide marking of the tunnelling packets based on the semantic map. As a summary, bringing the two aforementioned determinism-maintaining approaches together formed a solid framework for guaranteeing end-to-end QoS performance. Even though the IEC 61158 Type 10 network interface cards (NIC) with RToUDP extension could not be used as a native NIC of a VAN device in this phase, it can be counted on in future exploitation of the VAN technology. Nevertheless, the NICs with RToUDP were used to design and implement a TestQoS application specified and designed in T4.3 and T4.4, respectively. TestQoS is a test bed for evaluation of QoS parameters of communication paths using UDP datagrams as test traffic. Precision of 10 ns is possible thanks to the EDD providing access to precise counters. The test bed has provided a detailed insight into QoS performance qualitative and quantitative details within T4.5. The test bed has been used in numerous work packages in VAN project. Security aspects have been intensively focused in VAN, especially for communication over public networks, and potentially for inter-LAN communication. Virtual Private Network (VPN) tunnelling has been selected to be the best solution. Even though they formerly appeared to contradict with the realtime aspects, it was shown by the TestQoS that tunnelling the real-time traffic does not represent significant temporal overheads unless the tunnel is encrypted. Component Based Automation (CBA) model of IEC 61158 Type 10 has been introduced as well for further applications in the future. The CBA stack is less effective than IO with RToUDP extension. However, network infrastructure determinism can still be preserved. Additionally, a new Telecontrol Profile for IEC 61158 Type 10 has been defined in strong cooperation with WP7. The required VAN real-time services have been regarded in the ASE definition and can be engineered via web services. Most of the aforementioned solutions are integrated in the Manufacturing Automation showcase to prove their functionality.
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