Field networks

Maintaining the safety function of a device or a facility incorporating several elements depends on the proper functioning of each element involved in tliis function. Potential hazards related to the involvement of a field network in the maintenance of a safety function can be caused by  

The safety profile PROFlsafe defines the connection of intrinsically safe equipment (emergency stops, immaterial barriers, locks) to programmable controllers on PROFIBUS. The specific area of safety, most of whose constituents were previously connected by wire, may benefit from the multiple strengths of open communication on PROFIBUS. 

Based on the DP (decentralized peripherals) profile, PROFlsafe accepts RS 485 transmissions, fiber optics or lEC 1158-2. 

Equipment operating under PROFlsafe is able to function without limits in perfect harmony with standard equipment on the same cable. It is therefore a software solution that combines safe communication and standard transmission over a single channel, without any other special wiring. 

PROFlsafe takes into account any errors that may sneak into the standard serial transmission (repetition, loss, insertion, sequence error, delay, masquerade, data conuption, and addressing failures). It defines additional safety mechanisms that go beyond simple detection and error correction of the PROFIBUS access management. 

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Field ion microscopy (FIM), 16 503 24 74 Field network protocols, 20 672 Field separation, in petroleum processing, 18 645... 

Just as there are several varieties of evolutionary algorithm, so the neural network is available in several flavors. We shall consider feedforward networks and, briefly, Kohonen networks and growing cell structures, but Hop-field networks, which we shall not cover in this chapter, also find some application in science.31... 

Total installation and decommissioning costs for weU-field network. 

Digital Field Communications To provide increased data transmission capability between valve-mounted devices and the host control system, manufacturers are providing digital network means in their devices. The field networks, commonly Known as field buses, compete fiercely in the marketplace and have varying degrees of flexibility and specific application strengths. A prospective field bus... 

A particular field network protocol known as HART (Highway Addressable Remote Transducer) is the most widely used field network protocol. It is estimated that as of 2004 there are more than 14 million HART-enabled devices installed globally and that 70 percent... 

Status 15 centers around the world Status 10 fields/Network... 

Waller, C.L. and Kellogg, G.E. (1996) Adding chemical information to CoMFA models with alternative 3D QSAR fields. Network Science - Computational Chemistry, http //www.netsci.org/Science/ Compchem/featurelO.html. 

Hopfield networks have previously been used as optimisation tools but the weights have always been designed by hand. The contributions of this paper are twofold. It presents a method for automatically discovering the weight values for a Hop-field network from samples from a fitness function and an analysis of the capacity of such networks for storing local optima as attractor points. An analysis of linkage order and network capacity has shown that such second order networks can learn all of the attractor states of some higher order functions, even when they cannot reproduce the function output reliably. 

Wireless digital communication to and from the final control element is now commercially available. The advantage of a wireless field network is the potentially reduced cost vs. a wired installation. Hurdles for wireless transmissions include security from non-network sources, transmission reliability in the plant environment, limited bus speed, battery life, and the resistance of the process industry to change. Both point to point and mesh architectures are being commercialized at the device level. Mesh architectures utilize the other transmitting devices in the area to receive and then pass on any data transmission, thus re-routing communications around sources of interference. Multiple frequencies within the radio band are utilized to transmit data. 

We place ourselves in the case where we have a F-DI card, a Profmet field network with PROFIsafe profile, a safety CPU, a second field network (PROFIBUS) with a PROFIsafe profile, and a safety F-DO card (the data are based on documents from manufacturers that have been certified). 

For process control applications the Siemens S7-400F series of safety certified PLCs includes the Profisafe communication system which allows safety data to be transmitted within the Profibus DP message flames. Field networks are then permitted to transmit control and safety critical data over the same media. Remote I/O modules include an AS interface gateway certified for safety duties. The network software and safety interface products have been certified by TUV for SIL-3 duties in accordance with lEC 61508. 

To our knowledge, the first wireless communication adopted was based on infrared technology (Kahn Barry, 1997), due to the low cost of infraredcommimication devices. Radio Frequency (RF) rapidly replaced infrared technology, due to the increased use of Internet wireless Local Access Networks (LANs) (IEEE 802.11). In robotics, Wi-Fi Networks serve as a backbone for data concentration and networking. They are used in conjunction with short-range, low-power devices in a wireless field network to collect data from... 

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