Abstract
An important aspect when dealing with computer control systems is the impact of control delay upon the performance of the controlled item. Such control delay may be a consequence of the computer controlled implementation or, for the case of a network based control system, can be the consequence of the use of a communication network to interconnect sensors and actuators with the controller. Basically, control applications require a predictable delay between measurement and actuation, with small variability, i.e., small jitter. In this paper we present some simulation results concerning the impact of a varying control delay upon the performance of a DC-Motor, both for a centralized computer-controlled setup and for a network based control system. The results for the centralized setup were also experimentally confirmed. For the network-based setup it was used the h-BEB real-time communication protocol. The evaluated scenarios were simulated using the True Time simulator that is based in MATLAB/Simulink. The experimental tests were developed in LabVIEW, where the controller task was executed as a software routine. The tests consisted in the variation of the sampling period and control delay to determinate the steady region of the system.

Abstract
The integration between industrial applications and industrial networks technologies is a required condition to share information at the factory level. Industrial networks are known for having different communication protocols. Therefore wired gateway technologies play an important role in the integration of different protocol stacks, wherever that integration is necessary. However, if there are physical constraints that make hard setting up a wired gateway, such as, difficult access for the required cabling, the use of a wireless gateway may present both a technical and an economical advantage when compared with wired gateway. This paper illustrates two industrial automation case studies, where both solutions use ELPRO wireless gateways proposed by Tee Wise Company (R). The assessment results confirm that the use of wireless gateways may be an interesting solution for the industrial communication interconnection being analyzed. In this paper, we make a technical and economical assessment of the use of wireless gateways in industrial networks as a contributive solution for the integration of different industrial communication protocols.

Abstract
Distributed control systems operation strongly depends on the communication system performance. Therefore, their analysis becomes an important aspect to be considered, particularly in situations where communications have real-time constrains and the network operates on faulty environments. In this paper the behavior of PROFIBUS network in the presence of faults is analyzed. This analysis is performed in an experimental base supported by a real network. The network operation is disturbed through a set of fault injection experiments from which performance metrics related with PROFIBUS outage times are evaluated.

Abstract
WirelessHART currently appears as a promising solution for the last mile connection in process control applications. Most of these applications have stringent dependability requirements, where a system failure may result in economic losses, or damage for human life or the environment. Among the different type of faults that can lead to a system failure, permanent faults on network devices have a major impact. They can hamper communication over long periods of time and consequently they may disturb, or even disable, control algorithms with all resulting problems. In this work we perform a dependability evaluation of the best practices indicated by the HART Communication Foundation (HCF), when network devices are subject to permanent faults.

Abstract
In this paper is proposed a novel communication approach for implementation of parallel data fusion techniques in Wireless Sensor Networks. The approach is carried out by a distributed algorithm implemented in each network sensor node. In this approach, the network configures itself in order to adjust the number of messages sent periodically, establishing a tradeoff between the number of sent messages and the quality of data fusion (QoF). A prototype was implemented and experimental results show the effectiveness of this proposal.

Abstract
In this paper we make a comparative assessment between the RT-WiFi and HCCA approaches to handle real-time traffic in IEEE 802.11 networks operating in open communication environments. The main focus will be on the assessment of the admission control mechanism proposed for the RT-WiFi upper layer, that is based on a non-preemptive EDF scheduling algorithm combined with a mechanism that measures the blockage times on medium access of real-time stations due to retransmissions and delays. The goal is to achieve a good compromise between medium utilization and timeliness. This proposal is compared with HCCA, and the results show that RT-WiFi offers a significantly better behavior in what concerns the maximum number of admitted streams.