Wireless Technologies in Factory Automation

Abstract

Wireless technologies are utilised in consumer applications for several years, now. However, the operation of radio based communication systems in automation applications was considered doubtful for a long time. Primarily, the highly fluctuating quality of wireless transmission channels, compared to wired ones, was responsible for this fact. Transmitted electromagnetic waves experience reflexion, scattering, and diffraction, which may cause constructive or destructive interferences of the different signal copies arriving at the receiver. The direct consequences are packet errors and losses, resulting in higher transmission delays. Especially industrial propagation environments, with a lot of metallic surfaces and moving objects, are classified as demanding for wireless transmission. While fluctuations in latency and short losses of connections may be tolerated in consumer applications, exceeding given timelines in automation applications implies intolerable errors. The results are low plant availabilities and decreasing productivity. By means of the development of diverse wireless standards and the adaption of well-suited protocols for industrial applications, the end-users doubts could be reduced dramatically over the last decay. The advantages of wireless solutions are obvious. In harsh environments, mobile and rotating scenarios, or at positions, difficult to access, cable connections and sliding contacts represent a main source of error. In this context the error probability can be decreased and the maintenance intervals increased by the utilisation of wireless technologies. In addition to that, there is a great potential on saving time and money during planning, installation, and commissioning of plant sections. Many domains of the industrial automation already profit from the deployment of wireless solutions. With KNX RF (Konnex, 2006) and ZigBee (ZigBee Standards Organization, 2007) the first standards for building automation have been introduced. Within the scope of the HART 7 specifications (HART Communication Foundation, 2008) the first standard, WirelessHART, for the process automation was released in late 2007. Further standards, especially for the domain of factory automation, are expected to get published in 2010. In order to reduce costs and time during the development of wireless solutions, unlicensed frequency bands are typically used for operation. Moreover an almost worldwide harmonised operation is guaranteed. This tendency is very pronounced for the 2.45 GHz ISM (Industrial, Scientific, and Medical) frequency band. Because of the high availability, transceiver chips of commercial standards are 2 www.intechopen.com Factory Automation 30

Experimental and kinetic modeling study of n-pentane oxidation at 10 atm, Detection of complex low-temperature products by Q-Exactive Orbitrap

“…A wide range of cyclic ethers has been observed during fuels combustion [37,38]. Decomposition and cyclization of hydroperoxyalkyl radicals form cyclic ethers and hydroxyl radicals: • QOOH → cyclic ether + • OH [39]. Nagata et al [40] studied the formation pathway to 2-Methyltetrahydrofuran (2-Me-THF) during vapor-phase oxidation of pentane.…”

Middleware Communication System for Fixture based Flexible Manufacturing Systems

“…Publications have shown emerging work ushering in the wireless communication protocols into industrial networks. (Buda et al, 2010). To keep up with technological trends wireless technology was used for the development of the communication network.…”

“…Wireless technology offers flexibility; modules can be introduced to the system in a plug and play manner without having to worry about re-wiring. Factory propagation environments however, have many metallic surfaces and moving objects, which can be characterised as harsh conditions that can affect the operational quality of radio based communication systems (Buda et al, 2010). Wireless communication is implemented with ZigBee wireless protocol, a well-adapted technology for industrial applications.…”

“…ZigBee operates at 2.4GHz frequency, which lays in the bandwidth of frequency not affected by the interference in factories. (Buda et al, 2010). ZigBee is based on an IEEE 802.15.4 standard.…”