programmable logic controllers (PLCs) started out as mere replacements for banks of hard-wired relays. Today's evolved digital controllers play an integral role in automation and power systems. Recent innovations ...
详细信息
programmable logic controllers (PLCs) started out as mere replacements for banks of hard-wired relays. Today's evolved digital controllers play an integral role in automation and power systems. Recent innovations in CPU and network technology have opened up new opportunities for parallelized future control systems, such as software-based fault tolerance and real-time data analysis. Before these benefits can be unlocked, however, many challenges must be overcome. ABB Corporate Research is actively pursuing the future of real-time controllers by tackling determinism, flexibility, scalability and sequential algorithms.
The technological process of plasma spraying is complicated and there are many switches to be controlled. The present existing plasma spraying system is not reliable and liable to troubles. The paper introduces a prog...
详细信息
The technological process of plasma spraying is complicated and there are many switches to be controlled. The present existing plasma spraying system is not reliable and liable to troubles. The paper introduces a programmable controller of Model C60P to control the technological process of plasma spraying. It also introduces the control system of the detection circuit, the protection system. The authors designed the logic diagram of the technological process, the hardware of resisting high frequency interference, the interface distributing system and the programming software. It is proved that the improved equipment has overcome the defects of the original.
As the gap between PLCs and computer based control systems become narrower each day, the role of PLCs in control solutions constantly changes. In this article, a 1995 PLC survey is described. Compared to the previous ...
详细信息
As the gap between PLCs and computer based control systems become narrower each day, the role of PLCs in control solutions constantly changes. In this article, a 1995 PLC survey is described. Compared to the previous surveys, this survey has been revamped to better reflect the expanded range of features PLCs offer. In particular, a third alternative to the Yes/No format- that of Optional is introduced.
The ongoing trend to bring larger and faster devices to the programmablelogic (PLD) is entering an exciting era with the advent of devices in the millions of gates and new feature sets designed to promote system-on-a...
详细信息
The ongoing trend to bring larger and faster devices to the programmablelogic (PLD) is entering an exciting era with the advent of devices in the millions of gates and new feature sets designed to promote system-on-a-chip design. Items such as embedded memory, phase-locked loops (PLL), and multifunctional input/output will become common, while design aids like larger functional blocks and intellectual property will help designers maintain high levels of productivity while using the devices to their utmost performance. These changes will not result in the ultimate PLD or PLD design environment, rather, they will reflect the dynamism of the programmablelogic industry, which like the device themselves, alters as necessary to meet the needs of its users.
programmablelogic controller application (hereinafter PLC, from the English. programmablelogic controller) in the automation of today is already substantially spread out, one might say "nothing new". Howev...
详细信息
programmablelogic controller application (hereinafter PLC, from the English. programmablelogic controller) in the automation of today is already substantially spread out, one might say "nothing new". However, when it is said that the management of some machine, device or plant is created by PLC, most people automatically expect complicated and certainly expensive set of Control. The truth is that serious, complex and demanding applications today means the use of the PLC, even more of them, networked in the system. The aim of this text is to show that there are applications not so complicated when automation with the help of PLC can be justified.
Industrial process automation typically involves high costs for design and maintenance. Changes and modifications in the system throughout its life cycle are significant. PLC programmable controller is a digital compu...
详细信息
programmable logic controllers (PLCs) have become important building blocks for automated systems. Because they have constantly increased in capability while decreasing in cost, PLCs have solidified their position as ...
详细信息
programmable logic controllers (PLCs) have become important building blocks for automated systems. Because they have constantly increased in capability while decreasing in cost, PLCs have solidified their position as the device of choice for a wide variety of control tasks. One reason for the popularity of PLCs is their high reliability in harsh industrial environments;occasionally, however, things do go wrong and troubleshooting becomes necessary. Those unfamiliar with PLCs often fear troubleshooting a device that appears to be a mysterious 'black box', but once one gets over this black box syndrome, PLCs are actually easier to troubleshoot than traditional hard-wired control systems. The internal operation of a PLC can be monitored via a handheld programmer, terminal, or personal computer, and many indicator lights are provided for I/O troubleshooting.
Due to the rapid increase in digitalization and networking of systems, especially in industrial environments, the number of cyber-physical systems is increasing and thus the danger of possible attacks on such systems....
详细信息
ISBN:
(纸本)9783907144008
Due to the rapid increase in digitalization and networking of systems, especially in industrial environments, the number of cyber-physical systems is increasing and thus the danger of possible attacks on such systems. As demonstrated in several recent examples, a cyber attack on an industrial control system (ICS) can have catastrophic consequences for humans and machines. This is due to the communication networks between programmable logic controllers (PLC), actuators and sensors, which are usually vulnerable to attacks, as well as various processes or devices that are not sufficiently protected. In this paper, two possible attacks on a discrete event system (DES) are introduced, in which a running process, controlled by a PLC, is manipulated without being detected. Furthermore, a detection method for such attacks is presented.
New information about the capabilities of Stuxnet revealed in the recent documentary film 'Zero Days' has revived concerns about the potential impacts of cyber attacks on critical infrastructure such as power ...
详细信息
New information about the capabilities of Stuxnet revealed in the recent documentary film 'Zero Days' has revived concerns about the potential impacts of cyber attacks on critical infrastructure such as power stations, chemical plants and fuel refineries. The movie explains with chilling resonance how, in 2010, the state-sponsored Stuxnet worm managed to gain destructive control of the programmable logic controllers (PLCs), which automated electromechanical processes inside gas centrifuges used for isotopic separation of uranium at Iran's Natanz nuclear facility. While such attacks have caused their share of problems to power stations and utility assets around the world, the newer effects of ransomware has yet to openly turn its disruptive powers on the computerised systems that monitor or manage the physical state of an industrial or infrastructural control system - physical devices such as pumps and valves. This is set to change, warn industry experts, as cyber criminals figure out how to repurpose their dark arts into a profitable model for targets in operational technology (OT) environments.
There are several reasons why personal computers- (PC) based control cannot replace programmable logic controllers (PLC). First, the cost of a PC as a PLC replacement is too high for most market applications. The PC s...
详细信息
There are several reasons why personal computers- (PC) based control cannot replace programmable logic controllers (PLC). First, the cost of a PC as a PLC replacement is too high for most market applications. The PC solution requires additional computer peripherals that can cost $4,000, and perhaps even $10,000 more than the PLC solution. Second, protection against harsh environment, is intrinsic to a PLC's design and has a proven history of success. Next, desktop PCs have numerous parts that are sensitive to harsh environments. Such components include power supplies, metal oxide varistor- (MOV) based surge suppressors, and rotating media. Other issues are the simplicity of PLC programming and PLC's nonvolative memory.
暂无评论