S7-200与三菱变频器串行通信毕业论文概要

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毕业论文

课题: S7-200对三菱变频器远程控制摘要

随着计算机网络技术的发展及工厂自动化程度的不断提高 , 开放性和多功能的网络通信要求成为了 PLC 的必备条件。在实际应用中, PLC 主机与扩展模块之间要进行信息交换, PLC 主机与其他主机或其他设备之间也经常进行信息交换。所以通过这次课题的设计对 PLC 与变频器之间的通信方式得到一个初步的认识,这次的课题主要学习 S7-200与三菱变频器之间最基本的通信方式。通过查阅资料把课题拟定, S7-200与三菱变频器串行口通信研究。定好课题开始学习 S7-200以及三菱变频器的通信格式, 由 PLC 发出启动、停止、运行频率等指令,来控制变频器的运转及频率输出。在导师指导下经过多次修改、调试定下程序的梯形图。通过这次课题设计提高了自己独立工作的能力和创造力, 加强了对基础及专业的运用能力,让我对 PLC 又加深一步的了解。 PLC 作为工业自动控制的核心部分,单机编程和维护相对简单一点, 而工业网络通信要求同时兼顾稳定性、快速性、灵活性及与第三方设备的兼容性,所以工业网络通信成为工业自动化系统设置及实施的难点。变频器与 PLC 在自由口模式下通信,具有很大的灵活性,方便了工程应用。

Abstract

With the development of computer network technology and factory automation degree rise ceaselessly, Open and multi function network communication requirements of PLC become the essential condition. In practical application, the PLC host and extension module to exchange information between PLC host and other host, or other equipment also often exchange information. So through this topic design of communication between PLC and frequency converter means to get a preliminary understanding, this topic mainly to learn S7-200 and Mitsubishi Inverter between the most basic means of communication. Access to information through the research protocol, S7-200 and Mitsubishi Inverter serial port communication research. Set the task started learning S7-200 and Mitsubishi

Inverter communication format, by the PLC to start, stop, run the frequency of such instruction, to control the inverter operation and frequency output. In under the guidance of a mentor after several modifications, debugging set program ladder chart. Through this topic design improves their ability to work independently and creativity, strengthen the basic and professional skills, let I to PLC and to deepen the understanding of one pace. PLC as the core part of industrial automatic control, single programming and maintenance of relatively simple, while the industrial network communication requirements of both stability, rapidity, flexibility and compatibility with third party equipment, so the industrial communication networks become industrial automation system settings and

the difficulties of implementation. Frequency converter and PLC in free port mode of communication, it has great flexibility, convenient for engineering application.

摘要 .............................................................................................................................. I Abstract .......................................................................................................................... I目录 ..........................................................................................................................III 第一章绪论 ..................................................................................................................1 1.1 串行通信基本概念及特点 ....................................................................................... 1

1.2 串行通信的分类 ..................................................................................................... 1 1.2.1通信协议 .................................................................................................... 2 1.2.2通信设备 .................................................................................................... 3

第二章 PLC 的自由口串行通

信 .................................................................................5

2.1 自由口指令及应

用 . ................................................................................................. 5 2.1.1 自由口指

令 ............................................................................................... 5 2.1.2相关寄存器及标志 ...................................................................................... 5

2.2 PLC的格式设定 ..................................................................................................... 7第三章变频器通信 (本章由单璐所作 ..............................................................8 3.1 串行通讯功能 . ........................................................................................................ 8 3.2 变频器通信格式 ..................................................................................................... 8第四章程序 ................................................................................................................13 4.1 流程图 ................................................................................................................. 13 4.2 PLC连接变频器带动电动机启动接线图 ................................................................ 14 4.3 指令表 ................................................................................................................. 14 4.4 梯形图 ................................................................................................................. 18第五章结论 ................................................................................................................30 5.1 结论 . .................................................................................................................... 30致谢 ..........................................................................................................................31参考资料 ......................................................................................................................32

第一章绪论

1.1 串行通信基本概念及特点

串行通信是将数据字节分成一位一位的形式在一条传输线上逐个地传送

串行通信的特点:传输线少,长距离传送时成本低,且可以利用电话网等现成的设备,但数据的传送控制比并行通信复杂。

1.2 串行通信的分类异步通信与同步通信 1、异步通信

异步通信是指通信的发送与接收设备使用各自的时钟控制数据的发送和接收过程。为使双方的收发协调,要求发送和接收设备的时钟尽可能一致。

图 1-2 异步通信的发送与接受方式

异步通信是以字符 (构成的帧为单位进行传输, 字符与字符之间的间隙 (时间间隔是任意的, 但每个字符中的各位是以固定的时间传送的, 即字符之间不一定有“位间隔”的整数倍的关系, 但同一字符内的各位之间的距离均为“位间隔”的整数倍。

异步通信的特点:不要求收发双方时钟的严格一致,实现容易,设备开销较小, 但每个字符要附加 2~3位用于起止位, 各帧之间还有间隔, 因此传输效率不高。 2、同步通信

同步通信时要建立发送方时钟对接收方时钟的直接控制, 使双方达到完全同步。此时, 传输数据的位之间的距离均为“位间隔”的整数倍, 同时传送的字符间不

留间隙, 即保持位同步关系, 也保持字符同步关系。发送方对接收方的同步可以通过两种方法实现。

1.2.1通信协议