共查询到20条相似文献，搜索用时 171 毫秒
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介绍采用通用逻辑指令设计PLC控制程序的一种方法。采用该方法设计的控制程序具有易于掌握，可读性强等优点。 相似文献
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本文以三菱FX 2N系列PLC为例,介绍了一种PLC时序控制程序的编制方法,即应用触点比较指令将基准定时器的当前值分别与期望的若干个定时设定值相比较,用各触点比较指令的运行结果及其逻辑组合,来控制PLC的实际输出,实现PLC的时序控制功能。 相似文献
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根据钢厂循环水系统的工艺要求,系统硬件采用WinCC软件和S7-300PLC.通过WinCC与S7-300PLC之间通信实现了系统的检测和控制.根据梯形图LAD语言编写PLC的逻辑控制程序.所设计的系统达到了预期效果. 相似文献
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乔振民 《石家庄职业技术学院学报》2011,23(4):21-23
介绍了一种利用S7-200 PLC实现数码管显示并且设计简单的4人抢答器,它以比较指令、译码指令实现其功能.与一般的利用互锁指令相比,此设计更加简单,适于多人抢答. 相似文献
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根据电镀生产线控制要求,提出基于PLC的电镀生产线自动控制系统的设计.PLC顺序控制程序具有灵活强大的控制能力,能够满足电动机频繁操作的自动控制需要,使电镀生产线实现了操作简便,生产高效的目标. 相似文献
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《兰州石化职业技术学院学报》2021,21(2)
西门子公司生产的S7系列PLC是我国工业企业中使用量最大的PLC之一,在企业中由于PLC的大量使用,它们之间的控制和数据交换必然会非常频繁。设计了用1台S7-1200PLC控制2台S7-200 SMART PLC的实现方法,阐述了从硬件组网、通信程序编写到控制程序编写,希望对从事这方面研究的技术人员有所帮助。 相似文献
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王勋 《赤峰学院学报(自然科学版)》2021,(1):63-67
本设计以西门子公司的S7-200可编程逻辑器为中央处理模块,以两相步进电机为控制对象,介绍了西门子S7-200PLC的控制原理和系统总体设计方法,并从软件设计方面详细地讲解了如何用PLC的移位指令和高速脉冲输出指令实现对步进电机的控制. 相似文献
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《华夏少年(简快作文 )》2014,(5)
教师采用三菱FX-1S系列的PLC实现四节传送带的模拟控制,在I/O分配的基础上,进行PLC梯形图程序设计和运行功能分析。在程序设计上采用基本指令和功能指令来实现对四节传送带的控制。 相似文献
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Three rats were trained under a discrimination procedure in which responding was reinforced only following the repeated presentation of three bursts of white noise (S+). S? consisted of presentations of either two or four bursts of noise. All animals responded significantly more in the presence of S+ and, in two cases, showed lower response rates to both “2” and “4” stimuli. Responding by the third animal revealed differentiation between S+ and the stimulus “2,” but no reliable suppression to stimulus “4.” The present instances of discriminative control by the stimulus “3” replicate Fernandes and Church’s (1982) demonstration of control by sequential auditory stimuli in the rat. Moreover, because the present procedure involves adjacent S? values both greater as well as less than S+, these results extend our knowledge of the rat’s abilities with sequential auditory stimuli: Rats are capable of making intermediate numerical discriminations based upon something other than a simple many-versus-few dichotomy. 相似文献
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Four naive pigeons were given six generalization tests in extinction after periods of pretraining in which S+ appeared with food reinforcement and S? appeared in extinction. An analysis of sequential effects among presentations of test stimuli showed that the overall gradient was influenced differently by stimuli at the extremes of the continuum of test stimuli and by S+ and adjacent stimuli. Gradients consisting of responding in each stimulus when it was preceded by an extreme stimulus tended to peak at S+, while gradients produced when each stimulus was preceded by S+ or an adjacent stimulus tended to show a peak shift. This was true whether the overall gradient showed a peak shift or not. Two naive subjects were added and four additional tests were given after pretraining in which unequal frequencies of reinforcement accompanied both S+ and S?. Results of all 10 tests show that sequential effects occur during generalization testing in extinction and that these “local dimensional effects” are unlike local contrast. These stimulus-specific sequential effects may greatly influence overall gradient form. 相似文献
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Paul Craddock Jessica S. Wasserman Cody W. Polack Thierry Kosinski Charlotte Renaux Ralph R. Miller 《Learning & behavior》2018,46(2):171-181
Second-order conditioning (SOC; i.e., conditioned responding to S2 as a result of S1–US pairings followed by S2–S1 pairings) is generally explained by either a direct S2→US association or by an associative chain (i.e., S2→S1→US). Previous research found that differences in responses to S2 after S1 was extinguished often depended on the nature of the S2–S1 pairings (i.e., sequential or simultaneous). In two experiments with human participants, we examined the possibility that such differences result from S1 evoking S2 during extinction of S1 following simultaneous but not sequential S2–S1 pairings. This evocation of S2 by S1 following simultaneous pairings may have paired the evoked representation of S2 with absence of the outcome, thereby facilitating mediated extinction of S2. Using sequential S2-S1 pairings, both Experiments 1 and 2 failed to support this account of how extinction of S1 reduced responding to S2. Experiment 1 found that extinguishing S1 reduced responding to S2, while extinguishing S2 had little effect on responses to S1, although forward evocation of S1 during extinction of S2 paired the evoked representation of S1 with absence of the outcome. In Experiment 2, evocation of S2 during S1 nonreinforced trials was prevented because S2–S1 pairings followed (rather than proceeded) S1-alone exposures. Nevertheless, responding to S2 at test mimicked S1 responding. Responding to S2 was high in the context in which S1 had been reinforced and low in the context in which S1 had been nonreinforced. Collectively, these experiments provide additional support for the associative-chain account of SOC. 相似文献
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In three experiments using rats, we examined the role of a discriminative stimulus (S) in governing the relation between a response (R) and an outcome (O) in an appetitive instrumental learning paradigm. In each experiment, we attempted to distinguish between a simple S-O association and a hierarchical relation in which S is associated with the R-O association. We used three variations on discriminative training procedures and three different assessment techniques-for revealing the hierarchical structure. In Experiment 1, we employed a training procedure in which S signaled a change in the R-O relation but no change in the likelihood of O. Although such an arrangement should not produce an excitatory S-O association, it nevertheless generated an S that controlled responding and transferred that control to other responses. In Experiment 2, we used a discrimination procedure in which two Ss each had the same two Rs and Os occur in their presence but each S signaled that a different R-O combination would be in effect. This design provided the opportunity for equivalent pairwise associations among S, R, and O but unique hierarchical relations. The subjects learned the hierarchical structure, as revealed by the specific depressive effect of a subsequent lithium-chloride-induced devaluation of O on responding only in the presence of the S in which that response had led to that outcome. In Experiment 3, one S signaled two different R-O outcomes. Then, two new stimuli were presented with the original S; the R-O relations were retained in the presence of one of the added stimuli but were rearranged in the presence of the other. The added S came to control less responding when it was redundant with respect to the R-O relations than when it was informative. Although all of the results were of modest size and each has an alternative interpretation, together they provide converging evidence for the hierarchical role of S in controlling an R-O association. 相似文献
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Discrimination performance was investigated with pigeons using feature negative (FN) discrimination procedures which differed in the temporal arrangement of the stimuli on S? trials. In both procedures, a single common element was presented on reinforced (S+) trials. In thesimultaneous FN procedure, a distinguishing element was presented simultaneously with the common element of S? trials. In thesequential FN procedure, the distinguishing element preceded onset of the common element on S? trials. In two experiments, the sequential FN procedure yielded better discrimination performance. In Experiment 1, a summation test designed to separate learning and performance variables indicated that sequential FN subjects had learned the negative relationship between the distinguishing element and reinforcement while simultaneous FN subjects had not. In Experiment 2, summation and acquisition tests indicated that the distinguishing element developed inhibitory properties in the sequential FN procedure but not in the simultaneous FN procedure. 相似文献
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Steven J. Haggbloom 《Learning & behavior》1980,8(3):441-446
The effects of transitions from nonrewarded (N) to rewarded (R) trials (N-R transitions) on discriminative behavior in differential conditioning and subsequent resistance to extinction were investigated in two experiments. In Experiment 1, groups given N-R transitions within S+ were more resistant to discrimination (ran fast in S?) and extinction than were groups given a partial reinforcement (PRF) schedule in S+ devoid of N-R transitions. Experiment 2 indicated that N-R transitions that occur when an N trial in S? is followed by an R trial in S+ are as effective in increasing resistance to discrimination, but not resistance to extinction, as are N-R transitions that occur within S+. The sequential effects obtained here were highly similar to those in conventional PRF and support the view that differential conditioning and PRF are highly interrelated phenomena. The results are discussed in terms of the extension of sequential theory to differential conditioning and the importance of internal reward-produced cues in discrimination learning. 相似文献
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核糖体是细胞生长所需的蛋白质合成的动力工厂,每一个核糖体的大小为4兆而顿,有18S、5．8S、28S和5S四种RNA及80S等蛋白质组成,细胞中约有50％的RNA是核糖体RNA,这些RNA直接或间接地参与形成数百万的核糖体,因此,核糖体RNA基因的转录调控机制一直是细胞生长和细胞周期调控研究的热点,细胞通过进化已经形成一套完整的配合RNA聚合酶共同完成的核糖体RNA转录调控机制。本文从核糖体RNA基因结构出发,就染色质重塑、组蛋白乙酰化及细胞周期三个方面探讨核糖体RNA转录调控机制。 相似文献
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PLC顺序控制编程方法探讨 总被引：1，自引：0，他引：1
张琳 《甘肃广播电视大学学报》2000,10(2):55-56
本讨论和总结可编程控制器（PLC）实现顺序控制的四种编程方法,给出顺序控制梯形图,并对不同编程方法进行比较。 相似文献
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Bruce A. Murray Mary Jane McIlwain Chih‐hsuan Wang Geralyn Murray Stacie Finley 《Journal of Research in Reading》2019,42(1):123-136
Learning irregular words involves mental marking of irregular letters in the spelling, a process not fully understood. In a within‐subjects experiment, we manipulated the type of scaffolding given to beginning readers to evoke mental marking. We pretested to sort 103 kindergarten and first‐grade participants into sequential decoders, who decode letter by letter, and hierarchical decoders, who recognise vowel patterns. In the control phase, children read irregular words in sentence contexts with minimal scaffolding. In the experimental phase, participants read additional irregular words in sentence contexts by ‘operating on the word’ to mark irregular letters. Results indicated that the experimental condition induced better untimed word reading, but it did not improve spelling or reading in a flash presentation. Hierarchical decoders were significantly more successful than sequential decoders in untimed word reading, spelling and reading in the flash presentation. These results suggest that learning hierarchical decoding predisposes readers to learn irregular words. 相似文献