摘要
PLC自身具有高可靠性,但在高可靠性要求的应用场合依靠单个PLC可靠性来保证控制系统可靠是不够的。PLC冗余设计是提高控制系统可靠性最有效手段之一。本文以去年参与的某大型实验室环境控制工程的冗余设计为背景,在比较硬件和软件冗余的利弊之后,选用软件冗余设计方式,并概述其结构,分析系统性能。经过理论推导和实际使用证明此设计既提高控制系统可靠性和可用性,又显著降低控制系统成本,有广泛的应用前景;并对今后设计类似的系统,起到良好的借鉴作用。
PLC has the preeminent reliability in itself, but it is insufficient to rely on a single PLC to ensure the control system in high reliability occasion, The redundant design of PLC is the one of the most effective ways to improve the reliability of the control system, This essay uses the redundant design of a vast lab environmental control system project in which participated last year as background. After compared the advan- tages and disadvantages of the Hardware and software redundancy, the design method of software redundancy is selected, its structure and working principle are summarized, and its system performance are analyzed. After theoretical derivation and practice application, it proves that the software redundancy design not only increases the reliabil- ity and availability of the control system, but also reduces the cost of control system obviously. Therefore, it has extensive application prospect and a good reference for the design of similar system in the future.
