　　本文改进设计了手动式检测装置的气动系统，概述了改进后气动系统的工作原理及动作实现过程；针对各种控制方案的优缺点，确定用PLC做为控制系统的核心，并结合气动回路设计出检测装置的控制系统。该系统通过PLC控制电磁阀的开闭，从而控制气动回路中高压气体的流向，使装置完成各个运动过程，实现管件气密性检测。

　　该系统的运用可以使此装置实现自动化检测，提高检测效率。控制面板简单，易于操作。系统以可编程控制器为控制核心，使系统抗干扰能力强、可维护性好，且可以在比较恶劣的环境下工作，以适应工业化检测。

　　关键词：气密性；水检法；检测；控制系统

第一章绪论1

1.1选题的目的与意义1

1.2国内外发展状况与趋势1

1.2.1国内外的研究状况1

1.2.2发展趋势2

1.3课题的主要研究内容3

1.4本章小结3

第二章控制系统的总体方案设计4

2.1气动系统的改进设计4

2.1.1气动回路系统的原理4

2.1.2系统的运动过程7

2.2控制方案的选择8

2.3控制系统的硬件结构10

2.3.1系统的硬件组成10

2.3.2系统的硬件工作原理11

2.4本章小结11

第三章系统的硬件设计12

3.1可编程控制器（PLC）的选型12

3.1.1确定可编程控制器（PLC）的类型12

3.1.2 预选PLC的系列型号13

3.2方向控制阀的选择14

3.2.1确定控制元件类型14

3.2.2确定阀的机能14

3.2.3预选阀的系列型号16

3.3消声器的选择16

3.3.1确定消声器的类型16

3.3.2确定消声器的型号18

3.4压力表的选择18

3.4.1确定压力表的类型18

3.4.2确定压力表的型号20

3.5 I/O分配表21

3.6硬件系统接线图21

3.7本章小结22

第四章系统的软件设计23

4.1检测气密性装置的控制要求23

4.2 PLC的程序设计23

4.3 PLC的程序调试25

4.4本章小结26

结束语27

致谢28

参考文献29

1.1选题的目的与意义

　　本课题研究的是在工业生产中，由于某些原因而使产品出现铸造砂眼、裂纹、气孔等现象，致使产品气密性不合格，将会使产品在工作条件下失效，为了保证产品的质量和生产的安全，需要对这些零件的气密性进行检测。对于检测管件气密性的装置的研究可以使我们准确的测出其是否合格。因而对该课题的研究，也显得相当重要。

　　伴随着工业大规模生产的进一步深化，气密性检测从以前的机械制造业己经拓展到了现在的一般日用品行业、家用电器、食品包装、医疗器械等，这些行业对自己生产的产品进行气密性检测是必不可少的。例如管道燃气走进千家万户，燃气的安全使用关系着广大市民的生命安全；对燃气输送中的关键部件阀门的气密性的要求变得越来越高，而准确、可靠的检测阀体的气密性是防止发生燃气泄漏，确保生产生活安全的重要手段。可见零件的气密性检测在现代制造业中有着非常重要的地位，因此气密性检测的方法也显得很重要。然而在检测中我们如能通过系统自动完成，不仅可以节省成本，更可以提高检测效率，实现气密性的自动化检测，所以控制系统的研究尤为重要。

1.3课题的主要研究内容

　　本文针对水检法检测装置的控制系统设计，主要完成了以下研究内容：

　　　1.概述了水检法检测气密性装置的工作原理，明确其整个检测过程，提出改进方案。

　　　2.提出水检法检测装置的控制系统设计方案，通过比较，确定最优方案。

　　　3.确定控制系统的硬件设计，可编程控制器（PLC）的选型，电磁阀的选择、消声器的选择、压力表的选择以及硬件系统接线图。

　　　4.完成控制系统的软件设计，程序流程图、顺序功能图的设计，在实验室进行模拟调试。

1.4本章小结

　　本章首先介绍了所选课题的目的和意义，然后概述了气密性检测技术的控制系统在国内外的研究现状以及发展趋势，从而明确了论文的主要研究内容。

内容简介：: 附录二：指令表附录二：指令表附录一：梯形图附录一：梯形图西安文理学院本科毕业设计（论文）中期检查表题目金属管件气密性检测装置的控制系统设计学生姓名杜迎宾学号08102080212专业名称机械设计制造及其自动化指导教师韦炜检查时间2012-4-11班级08机械2班毕业设计（论文）进展情况通过对水检法检测管件气密性的相关资料学习，以及对整个设计的了解，现基本完成以下设计工作：1.完成水检法检测管件气密性装置的气动回路设计。2.完成水检法检测管件气密性装置的控制系统的设计方案。确定用可编程控制器（PLC）作为实验设计方案。3.完成水检法检测管件气密性装置的控制系统的硬件设计。此部分包括硬件的选择、PLC外部接线图以及I/O接口。下一步将进行水检法检测装置的控制系统的程序设计，并在实验室进行调试，完成实验方案的设计,以及撰写论文。指导教师意见1.该生清楚自己的工作内容和技术路线；2.能够按自身的进度要求完成相关设计；3.能够与指导教师保持正常的师生指导关系。综上所述，同意按照设计进度进行后续工作。签字：年月日教研室意见签字：年月日西安文理学院本科毕业设计（论文）任务书题目金属管件气密性检测装置的控制系统设计学生姓名杜迎宾学号08102080212专业班级机械设计制造及其自动化0802指导教师韦炜职称讲师教研室机械毕业设计（论文）任务与要求任务：在现代化生产中,产品气密性检测是必不可少的，设计合适的检测装置的控制系统，以优化检测效率，本课题旨在通过水检法检测管件气密性装置的控制系统设计，选择一种合适的方案并进行相关设计和实验。要求：1、收集和整理气密性检测装置的控制系统的相关资料； 2、通过对各种方法的分析和探讨，确定实验设计方案； 3、在此基础上编写并调试程序，完成相关设计； 4、撰写毕业论文。毕业设计（论文）工作进程起止时间工作内容寒假2周 2012.1.102012.3.4第35周 2012.3.52012.3.25第68周 2012.3.262012.4.15 第911周2012.4.162012.5.6第12周2012.5.72012.5.13第13周 2012.5.142012.5.20明确设计内容要求，查（借）阅资料，了解相关的知识，撰写开题报告。分析气密性检测装置的原理，探讨气密性检测装置的各种控制系统，拟定方案。确定总体设计方案，完成模块化设计，在实验室进行系统调试。撰写毕业论文。论文定稿并整理资料准备答辩。答辩。开始日期 2012-1-10 完成日期 2012-5-11 教研室主任（签字）系主任（签字） Programmable logic controllerA programmable logic controller (PLC) or programmable controller is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, amusement rides, or lighting fixtures. PLCs are used in many industries and machines. Unlike general-purpose computers, the PLC is designed for multiple inputs and output arrangements, extended temperature ranges, immunity to electrical noise, and resistance to vibration and impact. Programs to control machine operation are typically stored in battery-backed or non-volatile memory. A PLC is an example of a real time system since output results must be produced in response to input conditions within a bounded time, otherwise unintended operation will result.1. History The PLC was invented in response to the needs of the American automotive manufacturing industry. Programmable logic controllers were initially adopted by the automotive industry where software revision replaced the re-wiring of hard-wired control panels when production models changed. Before the PLC, control, sequencing, and safety interlock logic for manufacturing automobiles was accomplished using hundreds or thousands of relays, cam timers, and drum sequencers and dedicated closed-loop controllers. The process for updating such facilities for the yearly model change-over was very time consuming and expensive, as electricians needed to individually rewire each and every relay. In 1968 GM Hydramatic (the automatic transmission division of General Motors) issued a request for proposal for an electronic replacement for hard-wired relay systems. The winning proposal came from Bedford Associates of Bedford, Massachusetts. The first PLC, designated the 084 because it was Bedford Associates eighty-fourth project, was the result. Bedford Associates started a new company dedicated to developing, manufacturing, selling, and servicing this new product: Modicon, which stood for MOdular DIgital CONtroller. One of the people who worked on that project was Dick Morley, who is considered to be the father of the PLC. The Modicon brand was sold in 1977 to Gould Electronics, and later acquired by German Company AEG and then by French Schneider Electric, the current owner. One of the very first 084 models built is now on display at Modicons headquarters in North Andover, Massachusetts. It was presented to Modicon by GM, when the unit was retired after nearly twenty years of uninterrupted service. Modicon used the 84 moniker at the end of its product range until the 984 made its appearance. The automotive industry is still one of the largest users of PLCs.2. Development Early PLCs were designed to replace relay logic systems. These PLCs were programmed in ladder logic, which strongly resembles a schematic diagram of relay logic. This program notation was chosen to reduce training demands for the existing technicians. Other early PLCs used a form of instruction list programming, based on a stack-based logic solver. Modern PLCs can be programmed in a variety of ways, from ladder logic to more traditional programming languages such as BASIC and C. Another method is State Logic, a very high-level programming language designed to program PLCs based on state transition diagrams. Many early PLCs did not have accompanying programming terminals that were capable of graphical representation of the logic, and so the logic was instead represented as a series of logic expressions in some version of Boolean format, similar to Boolean algebra. As programming terminals evolved, it became more common for ladder logic to be used, for the aforementioned reasons. Newer formats such as State Logic and Function Block (which is similar to the way logic is depicted when using digital integrated logic circuits) exist, but they are still not as popular as ladder logic. A primary reason for this is that PLCs solve the logic in a predictable and repeating sequence, and ladder logic allows the programmer (the person writing the logic) to see any issues with the timing of the logic sequence more easily than would be possible in other formats.2.1 Programming Early PLCs, up to the mid-1980s, were programmed using proprietary programming panels or special-purpose programming terminals, which often had dedicated function keys representing the various logical elements of PLC programs. Programs were stored on cassette tape cartridges. Facilities for printing and documentation were very minimal due to lack of memory capacity. The very oldest PLCs used non-volatile magnetic core memory. More recently, PLCs are programmed using application software on personal computers. The computer is connected to the PLC through Ethernet, RS-232, RS-485 or RS-422 cabling. The programming software allows entry and editing of the ladder-style logic. Generally the software provides functions for debugging and troubleshooting the PLC software, for example, by highlighting portions of the logic to show current status during operation or via simulation. The software will upload and download the PLC program, for backup and restoration purposes. In some models of programmable controller, the program is transferred from a personal computer to the PLC though a programming board which writes the program into a removable chip such as an EEPROM or EPROM.3. Functionality The functionality of the PLC has evolved over the years to include sequential relay control, motion control, process control, distributed control systems and networking. The data handling, storage, processing power and communication capabilities of some modern PLCs are approximately equivalent to desktop computers. PLC-like programming combined with remote I/O hardware, allow a general-purpose desktop computer to overlap some PLCs in certain applications. Regarding the practicality of these desktop computer based logic controllers, it is important to note that they have not been generally accepted in heavy industry because the desktop computers run on less stable operating systems than do PLCs, and because the desktop computer hardware is typically not designed to the same levels of tolerance to temperature, humidity, vibration, and longevity as the processors used in PLCs. In addition to the hardware limitations of desktop based logic, operating systems such as Windows do not lend themselves to deterministic logic execution, with the result that the logic may not always respond to changes in logic state or input status with the extreme consistency in timing as is expected from PLCs. Still, such desktop logic applications find use in less critical situations, such as laboratory automation and use in small facilities where the application is less demanding and critical, because they are generally much less expensive than PLCs. In more recent years, small products called PLRs (programmable logic relays), and also by similar names, have become more common and accepted. These are very much like PLCs, and are used in light industry where only a few points of I/O (i.e. a few signals coming in from the real world and a few going out) are involved, and low cost is desired. These small devices are typically made in a common physical size and shape by several manufacturers, and branded by the makers of larger PLCs to fill out their low end product range. Popular names include PICO Controller, NANO PLC, and other names implying very small controllers. Most of these have between 8 and 12 digital inputs, 4 and 8 digital outputs, and up to 2 analog inputs. Size is usually about 4 wide, 3 high, and 3 deep. Most such devices include a tiny postage stamp sized LCD screen for viewing simplified ladder logic (only a very small portion of the program being visible at a given time) and status of I/O points, and typically these screens are accompanied by a 4-way rocker push-button plus four more separate push-buttons, similar to the key buttons on a VCR remote control, and used to navigate and edit the logic. Most have a small plug for connecting via RS-232 or RS-485 to a personal computer so that programmers can use simple Windows applications for programming instead of being forced to use the tiny LCD and push-button set for this purpose. Unlike regular PLCs that are usually modular and greatly expandable, the PLRs are usually not modular or expandable, but their price can be two orders of magnitude less than a PLC and they still offer robust design and deterministic execution of the logic.4. PLC Topics4.1 Features The main difference from other computers is that PLCs are armored for severe conditions (such as dust, moisture, heat, cold) and have the facility for extensive input/output (I/O) arrangements. These connect the PLC to sensors and actuators. PLCs read limit switches, analog process variables (such as temperature and pressure), and the positions of complex positioning systems. Some use machine vision. On the actuator side, PLCs operate electric motors, pneumatic or hydraulic cylinders, magnetic relays, solenoids, or analog outputs. The input/output arrangements may be built into a simple PLC, or the PLC may have external I/O modules attached to a computer network that plugs into the PLC.4.2 System scale A small PLC will have a fixed number of connections built in for inputs and outputs. Typically, expansions are available if the base model has insufficient I/O.Modular PLCs have a chassis (also called a rack) into which are placed modules with different functions. The processor and selection of I/O modules is customised for the particular application. Several racks can be administered by a single processor, and may have thousands of inputs and outputs. A special high speed serial I/O link is used so that racks can be distributed away from the processor, reducing the wiring costs for large plants.4.3 User interface PLCs may need to interact with people for the purpose of configuration, alarm reporting or everyday control. A simple system may use buttons and lights to interact with the user. Text displays are available as well as graphical touch screens. More complex systems use a programming and monitoring software installed on a computer, with the PLC connected via a communication interface.4.4 Communications PLCs have built in communications ports, usually 9-pin RS-232, but optionally EIA-485 or Ethernet. Modbus, BACnet or DF1 is usually included as one of the communications protocols. Other options include various fieldbuses such as DeviceNet or Profibus. Other communications protocols that may be used are listed in the List of automation protocols. Most modern PLCs can communicate over a network to some other system, such as a computer running a SCADA (Supervisory Control and Data Acquisition) system or web browser. PLCs used in larger I/O systems may have peer-to-peer (P2P) communication between processors. This allows separate parts of a complex process to have individual control while allowing the subsystems to co-ordinate over the communication link. These communication links are also often used for HMI devices such as keypads or PC-type workstations.4.5 Programming PLC programs are typically written in a special application on a personal computer, then downloaded by a direct-connection cable or over a network to the PLC. The program is stored in the PLC either in battery-backed-up RAM or some other non-volatile flash memory. Often, a single PLC can be programmed to replace thousands of relays. Under the IEC 61131-3 standard, PLCs can be programmed using standards-based programming languages. A graphical programming notation called Sequential Function Charts is available on certain programmable controllers. Initially most PLCs utilized Ladder Logic Diagram Programming, a model which emulated electromechanical control panel devices (such as the contact and coils of relays) which PLCs replaced. This model remains common today. IEC 61131-3 currently defines five programming languages for programmable control systems: FBD (Function block diagram), LD (Ladder diagram), ST (Structured text, similar to the Pascal programming language), IL (Instruction list, similar to assembly language) and SFC (Sequential function chart). These techniques emphasize logical organization of operations. While the fundamental concepts of PLC programming are common to all manufacturers, differences in I/O addressing, memory organization and instruction sets mean that PLC programs are never perfectly interchangeable between different makers. Even within the same product line of a single manufacturer, different models may not be directly compatible.5. PLC compared with other control systems PLCs are well-adapted to a range of automation tasks. These are typically industrial processes in manufacturing where the cost of developing and maintaining the automation system is high relative to the total cost of the automation, and where changes to the system would be expected during its operational life. PLCs contain input and output devices compatible with industrial pilot devices and controls; little electrical design is required, and the design problem centers on expressing the desired sequence of operations. PLC applications are typically highly customized systems so the cost of a packaged PLC is low compared to the cost of a specific custom-built controller design. On the other hand, in the case of mass-produced goods, customized control systems are economic due to the lower cost of the components, which can be optimally chosen instead of a generic solution, and where the non-recurring engineering charges are spread over thousands or millions of units. For high volume or very simple fixed automation tasks, different techniques are used. For example, a consumer dishwasher would be controlled by an electromechanical cam timer costing only a few dollars in production quantities. A microcontroller-based design would be appropriate where hundreds or thousands of units will be produced and so the development cost (design of power supplies, input/output hardware and necessary testing and certification) can be spread over many sales, and where the end-user would not need to alter the control. Automotive applications are an example; millions of units are built each year, and very few end-users alter the programming of these controllers. However, some specialty vehicles such as transit busses economically use PLCs instead of custom-designed controls, because the volumes are low and the development cost would be uneconomic. Very complex process control, such as used in the chemical industry, may require algorithms and performance beyond the capability of even high-performance PLCs. Very high-speed or precision controls may also require customized solutions; for example, aircraft flight controls.Programmable controllers are widely used in motion control, positioning control and torque control. Some manufacturers produce motion control units to be integrated with PLC so that G-code (involving a CNC machine) can be used to instruct machine movements.PLCs may include logic for single-variable feedback analog control loop, a proportional, integral, derivative or PID controller. A PID loop could be used to control the temperature of a manufacturing process, for example. Historically PLCs were usually configured with only a few analog control loops; where processes required hundreds or thousands of loops, a distributed control system (DCS) would instead be used. As PLCs have become more powerful, the boundary between DCS and PLC applications has become less distinct. PLCs have similar functionality as Remote Terminal Units. An RTU, however, usually does not support control algorithms or control loops. As hardware rapidly becomes more powerful and cheaper, RTUs, PLCs and DCSs are increasingly beginning to overlap in responsibilities, and many vendors sell RTUs with PLC-like features and vice versa. The industry has standardized on the IEC 61131-3 functional block language for creating programs to run on RTUs and PLCs, although nearly all vendors also offer proprietary alternatives and associated development environments.6. Digital and analog signals Digital or discrete signals behave as binary switches, yielding simply an on or off signal (1 or 0, True or False, respectively). Push buttons, limit switches, and photoelectric sensors are examples of devices providing a discrete signal. Discrete signals are sent using either voltage or current, where a specific range is designated as on and another as off. For example, a PLC might use 24 V DC I/O, with values above 22 V DC representing on, values below 2VDC representing off, and intermediate values undefined. Initially, PLCs had only discrete I/O. Analog signals are like volume controls, with a range of values between zero and full-scale. These are typically interpreted as integer values (counts) by the PLC, with various ranges of accuracy depending on the device and the number of bits available to store the data. As PLCs typically use 16-bit signed binary processors, the integer values are limited between -32,768 and +32,767. Pressure, temperature, flow, and weight are often represented by analog signals. Analog signals can use voltage or current with a magnitude proportional to the value of the process signal. For example, an analog 0 - 10 V input or 4-20 mA would be converted into an integer value of 0 - 32767. 可编程逻辑控制器可编程逻辑控制器（PLC）或可编程序控制器是用于机电过程自动化的数字计算机，例如控制机械厂生产线、游乐设施或照明装置。可编程控制器在许多工业和机器中使用。与通用的计算机不同的是，PLC是专为多个输入和输出管理，扩展温度范围、不受电磁噪音影响、抗震动和冲击所设计。控制器的操作程序通常存储在电池供电或非易失性的内存中。PLC是实时的系统，因为系统产生的输出结果必须在有限的时间内回馈到输入，否则会导致错误操作。1.历史 PLC发明是针对于美国汽车制造行业的需要。可编程逻辑控制器最初通过了在软件版本更换硬连线的控制板生产模式更改时的汽车工业。在PLC之前，控制、程序化和安全联锁逻辑制造汽车是使用上百或上千的继电器、凸轮计时器、鼓定序仪和专用的闭环控制器来完成的。在每年更新模型等设施转变过程是非常耗时并且成本高昂的，这是因为电工需要单独地再接电线给每个中转。在1968年 GM Hydramatic（自动输电分局）发布通用汽车公司的提议，电子替代布线中继系统。获奖的提案来自贝得福得，马萨诸塞的贝得福得同事。第一个PLC选定084，因为它是贝得福得同事的第八十四个项目。贝得福得同事建立了一家新的公司致力开发、生产、销售，和服务这一新产品：Modicon，代表模块化数字控制器。迪克莫利，被认为是PLC之父，他是从事该项目的人之一。1977年古尔德电子公司当前所有者收购法国施耐德电气公司同德国公司AEG并售予该品牌为Modicon。 084模型之一首次被设在北部安多弗的Modicon总部马萨诸塞州。这是专门为通用汽车服务的，并且经过了近二十多年的不间断服务。直至984出现，Modicon使用的84名字才在其产品范围中结束。汽车工业仍是PLC的最大用户之一。2.发展早期的可编程控制器是设计来取代继电器逻辑系统。这些可编程控制器的“阶梯逻辑”是与继电器逻辑示意图非常类似的。选择此程序表示法的目的是为了减少对现有技术人员的培训需求。其他早期的可编程控制器使用指令列表编程，基于一个堆栈编程逻辑求解器进行求解。现代可编程控制器在各种各样的方式可以被编程，从梯形逻辑语言到更加传统的编程语言例如BASIC和C语言。另一个方法是状态逻辑，被设计的一种非常高级编程语言根据状态转换图的可编程控制器编程。很多早期可编程控制器没有可编程终端的逻辑图形表示法，逻辑反而是被描绘成一系列在一些版本的布尔格式的逻辑表达式，类似于布尔代数。随着编程码发展，由于上述原因它变成更常见的梯形逻辑语言。更新的格式如国家逻辑和功能块（这是类似的逻辑描述使用数字逻辑集成电路时的方式）的存在，但它们仍没有梯形逻辑语言流行。一个主要原因是可编程控制器解决问题用一个可预测和重复的序列的逻辑，并且梯形逻辑语言可以用其他格式让程序员（写逻辑）的人看到逻辑的时间，所有问题更加容易地程序化。2.1编程早期的PLC，到80年代中期，都是用专有的编程版或专用编程终端，往往有专门的功能键，代表各种PLC程序逻辑元件。程序存储在盒式磁带盒上。由于缺少的内存容量很少用于打印设备。最古老的可编程控制器使用的是非易失性磁核心内存。最期PLC在个人计算机上使用应用软件编程。计算机连接到PLC通过以太网RS-232,RS-485或RS-422缆线连接。编程软件允许输入梯式逻辑编程。通常，软件提供了用于调试和故障排除的功能，例如在操作过程中或通过仿真的逻辑部分PLC软件突出显示当前状态。该软件将上传和下载PLC程序以便备份和恢复。在某些型号的PLC中虽然程序写入一个可移动的芯片，如EEPROM或EPROM，但该方案还是得从个人电脑传输到PLC编程版。3.功能PLC的功能经过多年的发展，包括连续的继电器控制，运动控制，过程控制，分布式控制系统和网络。一些现代PLC的数据处理，存储，处理能力和通信能力相当于台式电脑。PLC编程结合远程I/O硬件，一台通用台式计算机允许在某些应用中重叠使用某一可编程控制器。在重工业中PLC被认为没有这些桌面计算机为主的逻辑控制器的实际性强，因为PLC在台式计算机系统中运行不是很稳定，并且，因为台式计算机硬件没有被设计成耐温度、湿气、振动和耐用作为可编程控制器的处理器。除桌面基于逻辑的硬件局限之外，例如Windows操作系统不适合自己的确定性逻辑的执行，结果是PLC逻辑不可能总是对规定逻辑变化的输入状态与极端性预计的时间一致。尽管如此，这样桌面逻辑被应用在较不重要情况，像实验室自动化和小型设施中使用该应用程序的要求不高，因为他们的价格一般都远远低于昂贵的PLC。在最近数年，小产品称为PLR（可编程逻辑继电器），并且因为名字相似，变得更常见并被接受。这些很像PLC已经应用于轻工业，它只有少部分的输入/输出（例如一些真实的输入输出信号）参与，低成本，很理想。这些小设备尺寸和形状比较普通地几位制造商制作，并且由更大的PLC制作商来填满他们低端产品规格。俗名包括PICO控制器、纳米PLC和其他的小控制器。多数这些控制器有在8到12数字输入、4到8数字输出，多达2个模拟输入。尺寸通常是4英寸宽、3英寸高、3英寸深。大多数这样的设备有一个小邮票大小的液晶屏幕来观看简化梯子逻辑的输入/输出点（只有一小部分程序被可见于给定的时间）和状况，并且这些屏幕由一个电磁四通摇臂按钮操纵加上四个不同的用于浏览和编辑的逻辑电钮，类似于录像机遥控按钮。控制器大多数有一个小插座为通过连接RS-232或RS-485到个人计算机，以便程序员可能为编程使用简单的窗口应用而不是被迫使用微小的LCD和电钮。不像普通PLC，通常是模块化，大大扩展,控制器通常不会取模块化并且不是可扩展的，但是他们提供稳健设计的确定性和执行逻辑的价值比PLC少。4.可编程序控制器PLC4.1未来发展从其他计算机来看，主要区别是可编程控制器具有特殊条件（例如，灰尘、湿、热、冷）和具有广泛的输入/输出（I/O）安排的设施。这些是连接PLC的传感器和执行器。可编程控制器是读取限制开关、模拟过程变量（如温度和压力）以及位置复杂的定位系统。有些人利用机器系统来查看光源与照明。执行器使可编程控制器操作电子电机、气动或液压缸、磁继电器、电磁线圈的模拟输出。输入/输出的安排可以建立一个简单的可编程控制器、或可编程序控制器可以用外部的I/O模块连接插入的计算机网络。4.2系统规模一个小的PL

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