可编程控制器（PLC）的应用技术讲座 第六讲 模拟量控制和数据通讯

可编程控制器（ＰＬＣ）的应用技术讲座第六讲模拟量控制和数据通讯徐义亨（杭州模糊技术工程公司，杭州，３１００１２）在ＰＬＣ和ＤＣＳ的相互竞争过程中，ＰＬＣ把本属于ＤＣＳ胜任的模拟量控制、数据通讯联网等功能充实到ＰＬＣ中来，构成了既能控制开关量又能控制模...     

DCS及PLC供电系统改造体会

ＤＣＳ及ＰＬＣ供电系统改造体会石伟,任富,兰志利（内蒙古化肥厂仪表车间）内蒙古化肥厂已经运行的ＤＣＳ及ＰＬＣ供电系统是东洋公司根据多年的仪表运行实践安装的,通过我厂的开车及运行情况来看,该系统安全可靠的满足了ＤＣＳ及ＰＬＣ的运行,但也出现了一些问题,...     

PLC在硫化检验联动线控制系统中的应用

简要介绍了ＰＬＣ的功能特点及利用ＰＬＣ改造硫化检验联动线的方案，实际应用效果较好。     

可编程序控制器在进口轮胎成型机改造中的应用

在进口轮胎成型机的改造中,使用国产ＳＲ－２１可编程序控制器（ＰＬＣ）替代原机所用的ＳＭＣ２５ＰＬＣ,机器的电气系统部分傺出现过故障。重点介绍了ＳＲ－２１ＰＬＣ的硬件及软件设计。     

高压煤浆泵PLC的换型

本文叙述了高压煤浆泵ＰＬＣ换型的原因，并进行了换型前后比较，提出了ＰＬＣ换型工作的一般思路。     

浅析PLC在玻璃工业中的应用前景

分析了ＰＬＣ在玻璃工业应用的现状和前景,特别分析了玻璃工业自动化控制中ＰＬＣ系统将出现的一些特点和趋势。     

绝对型光电编码器和PLC在机械式轮胎硫化机中的应用

讲述了绝对型光电编码器和ＰＬＣ在机械式轮胎硫化机中的应用,重点阐明了格雷码如何在ＰＬＣ程序中用梯形图转换为二进制和ＢＣＤ码。     

浅谈PLC的安全性

从ＰＬＣ的概念出发，结合其使用的场合，在分析了系统的故障分布后，给出了增强ＰＬＣ安全性的措施。     

PLC网络的结构及其通信机制分析研究

列举了数种名ＰＬＣ网络，它们大多是三级或四级总线了网复合而成，具有良好的可扩展性及通信适应性，高层子网通用化与标准化的趋势使ＰＬＣ网络比较容易接入ＣＩＭＳ系统或大型集散系统。分析了ＰＬＣ网络其它各层采用专利协议的通信原理，存在问题及对策。     

花岗石双向切机 PLC 控制的设计研究

花岗石双向切机是花岗石薄板加工的重要设备,为提高其自动化程度,现代花岗石双向切机一般都采用ＰＬＣ可编程序控制器控制。本文根据双向切机的实际加工需要,结合ＰＬＣ控制的特点,讨论了花岗石双向切机ＰＬＣ控制系统的基本原理,以提高其整机性能。     

Characteristics of polymer light conduits from different manufacturing processes

The characteristics of polymer light conduits (PLCs) prepared from three different processes are compared: (1) a bulk polymerization and melt spinning process (PLC1), (2) a thermal polymerization (PLC2), and (3) a UV curing photopolymerization (PLC3–PLC4) of a monomer mixture in a fluorinated ethylene propylene tube. PLC1 and PLC2 were obtained from Toray and Lumenyte, respectively. New PLCs, PLC3 and PLC4, were prepared from the monomer mixtures consisted of methyl methacrylate, 2-ethyl-hexyl acrylate, and the crosslinking agent polyethylglycol 200 diacrylate and diallyl phthalate, respectively. All four polymer light conduits contain the acrylic moiety. PLC2 may also contain the plasticizer additives, which resulted in an excellent flexibility but with a poor thermal stability. The flexibilities of PLC2 and PLC3 were significantly improved from that of PLC1 due to the insertion of a plasticizer and the long alkyl chain monomer 2-EHA, respectively. The much larger numerical apertures of PLC2–PLC4 than that of PLC1 suggest that PLC2–PLC4 can have a wide angle application. The transmitted distance of PLC1 is larger than those of PLC2–PLC4. However, the illumination intensity of PLC1 is worse than those of PLC2–PLC4. This result indicates that PLC1 is suitable for the applications as PLCs with the characteristics of long distance and low illumination intensity, while PLC2–PLC4 are suitable for short distance and high illumination intensity applications. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2103–2109, 1997     

PLC的程序结构

介绍PLC几种典型的程序结构,为PLC的用户和国产PLC厂家提出了选择PLC程序结构的建议。     

Thermal expansivity and thermal conductivity of amorphous thermoplastic polyimide and polymer liquid crystal blends

Linear thermal expansivities α_L and thermal conductivities of polyimide (TPI) and polymer liquid crystal (PLC) blends were studied. The glass transition temperatures T_g of our amorphous TPI and the PLC are, respectively, 240 and 220°C. The addition of the PLC induces orientation through the channeling process, as predicted by an extension of the Flory statistical‐mechanical theory of PLCs (27). Channeling was observed at PLC concentrations as low as 5 wt%. Thermal conductivity decreases with the addition of the PLC to the TPI. The anisotropic expansivity of the blends shows a strong dependence on PLC concentration and orientation direction. The pure PLC shows a maximum on the along‐the‐flow expansivity vs. temperature curves and also negative α_L values. TPI addition moves the expansivities to positive values, but the maximum persists, even for 5% PLC only.     

Thermomechanical properties of radiation-modified blends of polyethylene with liquid crystalline copolyester

The results of investigation of gamma irradiated blends of high-density polyethylene (PE) with thermotropic polymer liquid crystal (PLC) are presented. The PLC used was a copolyester of 40% poly(ethylene terephthalate) with 60% p-(hydroxy-benzoic acid). The PLC content in the blends was 0, 5, and 10 wt%. The constituents were blended with the use of a single screw extruder. The specimens were prepared by compression molding. The irradiation of the samples was performed by a Co⁶⁰ γ-radiation source in inert atmosphere (argon) up to absorbed relatively low doses (up to 200 kGy; 1 Mrad = 10 kGy). The morphological, thermal, and mechanical properties were investigated for irradiated and unirradiated samples. The influence of gamma irradiation and addition of PLC on the temperature dependence of the elastic modulus as well as the effect of a “form memory” of the materials examined are discussed. It was found that an addition of the PLC affects substantially the stress-strain relationship in tension at temperatures above the melting point of PE for the irradiated samples. The features of thermomechanical behavior of the PE + PLC blends, previously irradiated and oriented, at isometrical heating and cooling were also established. The results obtained testify that the addition of PLC to PE makes it possible to improve considerably the thermosetting properties of the heat-shrinkable polymeric products.     

Rigid-chain polyesters grafted with flexible-chain vinyl polymers

The concept of “molecular reinforcement” has been advanced, in the last decade, as an alternative to conventional fibre reinforcement of thermoplastics: In blends with normal (flexible-chain) thermoplastics, rigid chains of main-chain LC polymers (PLC) can act as strengthening fibres on the molecular scale. However, the rigid PLC chains must be well dispersed which is improbable since PLC and normal polymers are usually incompatible. A related concept is “micellar reinforcement”: Graft copolymers made of a rigid-chain PLC backbone and flexible-chain grafts can form a microphase morphology of cylinderic micelles where the PLC chains act as reinforcing fibres on a micellar scale. Such rigid-flexible graft copolymers are discussed in this study. They were pepared from a polyester of terephthaloyl, dihexoxyterephthaloyl and phenylhydroquinone moieties with special comonomer units carrying a double bond onto which styrene was grafted via radical copolymerisation. Grafting occurred with high efficiency, leading to products with the desired morphology of cyclindric micelles.     

可编程序控制器工程设计探讨

可编程序控制器（PLC）广泛地应用于工业生产的各个流程，如何正确安装PLC硬件以及PLC外围设备的合理配置是PLC能否正常稳定运行的关键。     

基于PLC的三相绕线式异步电机启动控制

介绍三相绕线式异步电动机转子串电阻启动继电接触器控制电路。以三菱FX2N系列PLC为控制器件,根据绕线式异步电动机转子串电阻启动控制的要求,改造继电接触器控制电路,设计了PLC输入输出接线图和梯形图程序,编写了控制程序语句指令表,分析了启动控制工作过程。     

Bacillus Mycoides磷脂酶C部分特性研究

对一种纯化自Bacillus mycoides 970发酵上清液的磷脂酶C的部分特性进行了研究.SDS-PAGE检测表明该纯化磷脂酶C由一条多肽链组成,分子量为75.1 kDa.热稳定性实验表明该纯化磷脂酶C对温度敏感,具有热不稳定性.金属离子依赖性检测表明该纯化磷脂酶C属于金属磷脂酶C家族,Ca2 、Mg2 、Zn2 和Ba2 对该磷脂酶C催化活性的发挥必不可少.血平板及卵黄平板检测表明该磷脂酶C没有溶血活性和卵磷脂酶活性.     

PPI协议分析

使用软件监听串口,记录Step7-Micro/SIN与S7-200 PLC通讯的PPI协议报文,参照PROFIBUS总线通讯协议,分析出PPI协议报文关键帧格式,实现读、写、锁定、解锁、连接测试、开停PLC等常用功能,可用于开发基于S7-200系列PLC、使用PPI协议进行通讯的上位机程序或轻量级的现场设备.     

基于Modicon PLC和intouch的污水处理控制系统

介绍了污水处理系统中Modicon PLC和intouch组态软件的应用。详细阐述了该系统的硬件及软件组成以及PLC的具体配置,软件的编程思想及流程。