外文翻译--无杆气缸机械手及其控制系统的设计

中文译文

理解S7--200网络通讯的基本概念

为网络选择通讯接口

S7--200可以满足您的通讯和网络需求，它不仅支持简单的网络，而且支持比较复杂的网络。S7--200提供了通讯手段，使您可以用它与那些使用自己的通讯协议的设备，例如：打印机和称重天平等进行通讯。

S7--200可以支持各种类型的通讯网络。在SET PG/PC Interface属性对话框中进行网络选择。一个选定的网络将被作为一个接口来使用。能够访问这些通讯网络的各类接口包括：

1.多主站PPI电缆 2.CP通讯卡 3.以太网通讯卡

通过下列步骤，您可以为STEP 7--Micro/WIN选择通讯接口。参见图7-1。 1. 在通讯设置窗口中双击图标。 2. 为STEP 7--Micro/WIN选择接口参数。

图7-1 STEP 7--Micro/WIN通讯接口

2 1 多主站PPI电缆

S7--200可以通过两种不同类型的PPI多主站电缆进行通讯。这些电缆允许通过RS--232或USB接口进行通讯。

如图7-2所示，选择PPI多主站电缆的方法很简单。只需执行以下步骤即可： 1. 在Set PG/PC Interface属性页中，点击属性按钮。 2. 在属性页中，点击本地连接标签。 3. 选中USB或所需的COM端口。

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图7-2 PPI多主站电缆选择

2 3 1 提示

请注意，一次只能使用一个USB接口。

提示

本手册的实例使用的是RS--232/PPI多主站电缆。原先的PC/PPI电缆已RS--232/PPI多主站电缆替代。另外，USB/PPI电缆也适用于这些实例。关于这些电缆的订货号，可参见附录C。

在PROFIBUS网络上使用主站和从站器件。

S7--200支持主--从网络，并能在PROFIBUS网络中充当主站或从站，而STEP 7--Micro/WIN只能作为主站。

主站

网络上的主站器件可以向网络上的其它器件发出要求。主站也可以对网络上其它主站的要求作出响应。典型的主站器件包括：STEP 7--Micro/WIN、TD200等HMI产品和S7--300或S7--400 PLC。在向其它S7--200发出请求以获取信息（点对点通讯）时，S7--200是作为主站的。

提示

如果网络上有其它主站，TP070将无法工作。

从站

配置为从站的器件只能对其它主站的要求作出响应，自己不能发出要求。对于多数情况，S7--200被配置为从站。作为从站，S7--200响应主站的要求。作为从站时，S7--200将负责响应来自某网络主站器件（如操作员面板或STEP 7--Micro/WIN）的请求。

设置波特率和站地址

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数据通过网络传输的速度是波特率。其单位通常为Kbaud或者Mbaud。波特率用于量度在给定时间内传输数据的多少。比如，19.2k的波特率即表示传输速率为每秒19200比特。在同一个网络中通讯的器件必须被配置成相同的波特率。因此，网络的最高波特率取决于连接在该网络上的波特率最低的设备。表7-1中列出了S7--200支持的波特率。

表7-1 S7--200支持的波特率 网络 标准网络 使用EM277 自由口模式 波特率 9.6K到187.5K 9.6K到12M 1200到115.2K 在网络中要为每个设备指定唯一的站地址。唯一的站地址可以确保数据发送到正确的设备或者来自正确的设备。S7--200支持的网络地址为从0到126。如果某S7--200带有两个端口，那么每个端口都会有一个网络地址。表7-2列出了S7--200设备的缺省（工厂）设置。

表7-2 S7--200设备的缺省站地址 S7--200设备 STEP 7--Micro/WIN HMI（TD200、TP或OP） S7--200 CPU 缺省地址 0 1 2 为STEP 7--Micro/WIN设置波特率和站地址

您必须为STEP 7--Micro/WIN配置波特率和站地址。其波特率必须与网络上其它设备的波特率一致，而且站地址必须唯一。

通常，您不需要改变STEP 7--Micro/WIN的缺省站地址0。如果网络上还含有其它编程工具包，那么您可能需要改动STEP 7--Micro/WIN的站地址。

如图7-3所示，为STEP 7--Micro/WIN配置波特率和站地址非常简单。在操作栏中点击通讯图标，然后执行以下步骤：

图7-3 配置STEP 7--Micro/WIN

1. 在通讯设置窗口中双击图标。

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2. 在Set PG/PC Interface对话框中点击属性按钮。 3. 为STEP 7--Micro/WIN选择站地址。 4. 为STEP 7--Micro/WIN选择波特率。

为S7--200设置波特率和站地址

您也必须为S7--200配置波特率和站地址。S7--200的波特率和站地址存储在系统块中。在为S7--200设置了参数之后，您必须将系统块下载至S7--200中。每一个S7--200通讯口的波特率缺省设置为9.6k，站地址的缺省设置为2。

如图7-4所示，使用STEP 7--Micro/WIN为S7--200设置波特率和站地址。您可以在操作栏中点击系统块图标或者在命令菜单中选择View > Component >System Block，然后执行以下步骤：

1. 为S7--200选择站地址。 2. 为S7--200选择波特率。 3. 下载系统块到S7--200。

图7-4 配置S7-200 CPU

1 2 提示

可以选择各种波特率。在下载系统块期间，STEP 7--Micro/WIN将会验证所选的波特率。如果选定的波特率可能会妨碍STEP 7--Micro/WIN与其它S7--200进行通讯，那么它将不被下载。

设置远端地址

在将新设置下载到S 7 -- 2 0 0 之前， 您必须为STEP 7--Micro/WIN（本地）的通讯（COM）口和S7-- 200（远端） 的地址作配置，使它与远端的S7--200的当前设置相匹配。如图7-5所示。

在下载了新设置后，您可能需要重新配置PG/PC接口波特率设置（如果新设置与远端S7--200 的设置不同）。关于波特率的配置，可参考图7-3。

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图7-5 配置STEP 7--Micro/WIN

在网络上寻找S7--200 CPU

您可以寻找并且识别连接在网络上的S7--200。在搜索S7--200时，您也可以寻找特定波特率上的网络或所有波特率上的网络。

只有在使用PPI多主站电缆时，才能实现全波特率搜索。若在使用CP卡进行通讯的情况下，该功能将无法实现。搜寻从当前选择的波特率开始。

1. 打开通讯对话框并双击刷新图标开始搜寻。

2. 要使用所有波特率搜寻，选中在所有波特率下搜寻复选框。 为网络选择通讯协议

下面是S7--200 CPU所支持的协议的总览。 1. 点对点接口（PPI） 2. 多点接口（MPI） 3. PROFIBUS

图7-6 搜索网络上的CPU

在开放系统互联（OSI）七层模式通讯结构的基础上，这些通讯协议在一个令牌环网络上实现。令牌环网络符合欧洲标准EN 50170中定义的PROFIBUS标准。这些协议是非同步的字符协议，有1位起始位、8位数据位、偶校验位和1位停止位。通讯结构依赖于特定的起始字符和停止字符、源和目的站地址，报文长度和数据校验和。在波特率一致的情况下，这些协议可以同时在一个网络上运行，并且互不干扰。如果带有扩展模块CP243--1和CP243--1 IT，那么S7--200也能运行在以太网上。

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PPI协议

PPI是一种主--从协议：主站器件发送要求到从站器件，从站器件响应，参见图7-7。从站器件不发信息，只是等待主站的要求并对要求作出响应。

主站靠一个PPI协议管理的共享连接来与从站通讯。PPI并不限制与任意一个从站通讯的主站数量，但是在一个网络中，主站的个数不能超过32。

图7-7 PPI 网络

如果在用户程序中使能PPI主站模式，S7--200 CPU在运行模式下可以作主站。（参见附录B中SMB30的描述）在使能PPI主站模式之后，可以使用网络读写指令来读写另外一个S7--200。当S7--200作PPI主站时，它仍然可以作为从站响应其它主站的请求。

PPI高级允许网络设备建立一个设备与设备之间的逻辑连接。对于PPI高级，每个设备的连接个数是有限制的。S7--200支持的连接个数如表7-3所示。所有的S7--200 CPU都支持PPI和PPI高级协议，而EM277模块仅仅支持PPI高级协议。

表7-3 S7--200 CPU和EM277模块的连接个数模块波特率连接数

表7-3 S7--200 CPU和EM277模块的连接个数 模块 S7--200CPU 通讯口0 通讯口1 EM277 波特率 9.6k、19.2k或187.5k 9.6k、19.2k或187.5k 9.6k到12M 波特率连接数 4 4 6（每个模块） MPI协议

MPI允许主--主通讯和主--从通讯，参见图7-8。与一个S7--200 CPU通讯，STEP 7--Micro/WIN建立主--从连接。MPI协议不能与作为主站的S7--200 CPU通讯。

网络设备通过任意两个设备之间的连接通讯（由MPI协议管理）。设备之间通讯连接的个数受S7--200CPU或者EM277模块所支持的连接个数的限制。S7--200支持的连接个数如表7-3所示。

对于MPI协议，S7--300和S7--400 PLC可以用XGET和XPUT指令来读写S7--200的数据。要得到更多关于这些指令的信息，参见S7--300或者S7--400的编程手册。

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图7-8 MPI网络

PROFIBUS协议

PROFIBUS协议通常用于实现与分布式I/O（远程I/O）的高速通讯。可以使用不同厂家的PROFIBUS设备。这些设备包括简单的输入或输出模块、电机控制器和PLC。

PROFIBUS网络通常有一个主站和若干个I/O从站，参见图7-9。主站器件通过配置可以知道I/O从站的类型和站号。主站初始化网络使网络上的从站器件与配置相匹配。主站不断地读写从站的数据。图7-9 PROFIBUS网络。

图7-9 PROFIBUS网络

当一个DP主站成功配置了一个DP从站之后，它就拥有了这个从站器件。如果在网上有第二个主站器件，那么它对第一个主站的从站的访问将会受到限制。

TCP/IP协议

通过以太网扩展模块（CP243--1）或互联网扩展模块（CP243--1 IT），S7--200将能支持TCP/IP以太网通讯。表7-4列出了这些模块所支持的波特率和连接数。

表7-4 以太网模块（CP243--1）和互联网模块（CP243--1 IT）的连接数。

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表7-4 以太网模块（CP243--1）和互联网模块（CP243--1 IT）的连接数 模块 以太网（CP243--1）模块 互联网（CP243--1 IT）模块 波特率 10到100兆 1个STEP 7--Micro/WIN连接 连接数 8个普通连接 若需更多信息，可参考SIMATIC NET CP243--1工业以太网通讯处理器手册或SIMATIC NETCP243--1 IT工业以太网及信息技术通讯处理器手册。

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英文资料原文

Understanding the Basics of S7-200 Network Communications Selecting the Communication Interface for Your Network

by Moniruzzaman, Mohammad.; M.A.Sc.; Concordia University (Canada).; 2006;

The S7-200 is designed to solve your communications and networking needs by supporting not only the simplest of networks but also supporting more complex networks. The S7-200 also provides tools that allow you to communicate with other devices, such as printers and weigh scales which use their own communications protocols.

The S7-200 supports many different types of communication networks. The selection of a network is performed within the Set PG/PC Interface property dialog. A selected network is referred to as an Interface. The different types of interfaces available to access these communication networks are:

1. PPI Multi-Master cables 2. CP communication cards 3. Ethernet communication cards

To select the communication interface for STEP 7--Micro/WIN, you perform the following steps. See Figure 7-1.

1. Double-click the icon in the Communications Setup window. 2. Select the interface parameter for

Figure 7-1 STEP 7--Micro/WIN Communications Interface

PPI Multi-Master Cables

1 2 The S7-200 supports communication through two different types of PPI Multi-Master cables. These cable types permit communication through either an RS-232 or a USB interface.

As shown in Figure 7-2, selecting the PPI Multi-Master cable type is simple. You perform the following steps:

1. Click the Properties button on the Set PG/PC Interface property page.

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2. Click the Local Connection tab on the Properties page. 3. Select the USB or the desired COM port.

Figure 7-2 PPI Multi-Master Cable Selection

Tip

Please note that only one USB cable can be used at a time. Tip

Examples in this manual use the RS-232/PPI Multi-Master cable. The RS-232/PPI Multi-Master cable replaces the previous PC/PPI cable. A USB/PPI Multi-Master cable is also available. Refer to Appendix E for order numbers.

Using Master and Slave Devices on a PROFIBUS Network

The S7-200 supports a master-slave network and can function as either a master or a slave in a PROFIBUS network, while STEP 7--Micro/WIN is always a master. Masters

A device that is a master on a network can initiate a request to another device on the network. A master can also respond to requests from other masters on the network. Typical master devices include STEP 7--Micro/WIN, human-machine interface devices such as a TD 200, and S7-300 or S7-400 PLCs. The S7-200 functions as a master when it is requesting information from another S7-200 (peer-to-peer communications). Tip

A TP070 will not work on a network with another master device. Slaves

A device that is configured as a slave can only respond to requests from a master device; a slave never initiates a request. For most networks, the S7-200 functions as a slave. As a slave device, the S7-200 responds to requests from a network master device, such as an operator panel or STEP 7--Micro/WIN. Setting the Baud Rate and Network Address

The speed that data is transmitted across the network is the baud rate, which is typically measured in units of kilo baud (kbaud) or mega baud (Mbaud). The baud rate measures how much data can be transmitted

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within a given amount of time. For example, a baud rate of 19.2 kbaud describes a transmission rate of 19,200 bits per second.

Every device that communicates over a given network must be configured to transmit data at the same baud rate. Therefore, the fastest baud rate for the network is determined by the slowest device connected to the network. Table 7-1 lists the baud rates supported by the S7-200.

Table 7-1 Baud Rates Supported by the S7-200 Network Standard Network Using an EM 277 Freeport Mode Baud Rate 9.6 kbaud to 187.5 kbaud 9.6 kbaud to 12 Mbaud 1200 baud to 115.2 kbaud The network address is a unique number that you assign to each device on the network. The unique network address ensures that the data is transferred to or retrieved from the correct device. The S7-200 supports network addresses from 0 to 126. For an S7-200 with two ports, each port has a network address. Table 7-2 lists the default (factory) settings for the S7-200 devices.

Table 7-2 Default Addresses for S7-200 Devices S7-200 Device STEP 7--Micro/WIN HMI (TD 200, TP, or OP) S7-200 CPU Setting the Baud Rate and Network Address for STEP 7--Micro/WIN

You must configure the baud rate and network address for STEP 7--Micro/WIN. The baud rate must be the same as the other devices on the network, and the network address must be unique.

Typically, you do not change the network address (0) for STEP 7--Micro/WIN. If your network includes another programming package, you might need to change the network address for STEP 7--Micro/WIN.

As shown in Figure 7-3, configuring the baud rate and network address for STEP 7--Micro/WIN is simple. After you click the Communications icon in the Navigation bar, you perform the following steps:

1. Double-click the icon in the Communications Setup window. 2. Click the Properties button on the Set PG/PC Interface dialog box. 3. Select the network address for STEP 7--Micro/WIN. 4. Select the baud rate for STEP 7--Micro/WIN.

Default Address 0 1 2

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Figure 7-3 Configuring STEP 7--Micro/WIN

Setting the Baud Rate and Network Address for the S7-200

You must also configure the baud rate and network address for the S7-200. The system block of the S7-200 stores the baud rate and network address. After you select the parameters for the S7-200, you must download the system block to the S7-200.

The default baud rate for each S7-200 port is 9.6 kbaud, and the default network address is 2.

As shown in Figure 7-4, use STEP 7--Micro/WIN to set the baud rate and network address for the S7-200. After you select the System Block icon in the Navigation bar or select the View > Component > System Block menu command, you perform the following steps:

1. Select the network address for the S7-200. 2. Select the baud rate for the S7-200. 3. Download the system block to the S7-200.

4 3 2 1

Figure 7-4 Configuring the S7-200 CPU

Tip

1 2 Selection of all baud rate options is permitted. STEP 7--Micro/WIN validates this selection during the download of the System Block. Baud rate selections that would prevent STEP 7--Micro/WIN from communicating with the S7-200 are prevented from being downloaded. Setting the Remote Address

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Before you can download the updated settings to the S7-200, you must set both the communications (COM) port of STEP 7--Micro/WIN (local) and the address of the S7-200 (remote) to match the current setting of the remote S7-200. See Figure 7-5.

After you download the updated settings, you may need to reconfigure the PG/PC Interface baud rate setting (if different from the setting used when downloading to the remote S7-200). Refer to Figure 7-3 to configure the baud rate.

Figure 7-5 Configuring STEP 7--Micro/WIN

Searching for the S7-200 CPUs on a Network

You can search for and identify the S7-200 CPUs that are attached to your network. You can also search the network at a specific baud rate or at all baud rates when looking for S7-200s.

Only PPI Multi-Master cables permit searching of all baud rates. This feature is not available if communicating through a CP card. The search starts at the baud rate that is currently selected.

1. Open the Communications dialog box and double-click the Refresh icon to start the search. 2. To search all baud rates, select the Search All Baud Rates check box. 2. Selecting the Communications Protocol for Your Network

The following information is an overview of the protocols supported by the S7-200 CPUs. 1. Point-to-Point Interface (PPI) 2. Multi-Point Interface (MPI) 3. PROFIBUS

Figure 7-6 Searching for CPUs on a Network

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Based on the Open System Interconnection (OSI) seven-layer model of communications architecture, these protocols are implemented on a token ring network which conforms to the PROFIBUS standard as defined in the European Standard EN 50170. These protocols are asynchronous, character-based protocols with one start bit, eight data bits, even parity, and one stop bit. Communications frames depend upon special start and stop characters, source and destination station addresses, frame length, and a checksum for data integrity. The protocols can run on a network simultaneously without interfering with each other, as long as the baud rate is the same for each protocol.

Ethernet is also available for the S7-200 CPU with expansion modules CP243--1 and CP243--1 IT. PPI Protocol

PPI is a master-slave protocol: the master devices send requests to the slave devices, and the slave devices respond. See Figure 7-7. Slave devices do not initiate messages, but wait until a master sends them a request or polls them for a response.

Masters communicate to slaves by means of a shared connection which is managed by the PPI protocol. PPI does not limit the number of masters that can communicate with any one slave; however, you cannot install more than 32 masters on the network.

Figure 7-7 PPI Network

S7-200 CPUs can act as master devices while they are in RUN mode, if you enable PPI master mode in the user program. (See the description of SMB30 in Appendix D.) After enabling PPI master mode, you can use the Network Read or the Network Write instructions to read from or write to other S7-200s.

While the S7-200 is acting as a PPI master, it still responds as a slave to requests from other masters. PPI Advanced allows network devices to establish a logical connection between the devices. With PPI Advanced, there are a limited number of connections supplied by each device. See Table 7-3 for the number of connections supported by the S7-200.

All S7-200 CPUs support both PPI and PPI Advanced protocols, while PPI Advanced is the only PPI protocol supported by the EM 277 module.

Table 7-3 Number of Connections for the S7-200 CPU and EM 277 Modules Module S7-200 CPU Port 0 Port 1 Baud Rate 9.6 kbaud, 19.2 kbaud, or 187.5 kbaud 9.6 kbaud, 19.2 kbaud, or 187.5 kbaud EM 277 Module

Connections 4 4 6 per module 9.6 kbaud to 12 Mbaud 14

MPI Protocol

MPI allows both master-master and master-slave communications. See Figure 7-8. To communicate with an S7-200 CPU, STEP 7--Micro/WIN establishes a master--slave connection. MPI protocol does not communicate with an S7-200 CPU operating as a master.

Network devices communicate by means of separate connections (managed by the MPI protocol) between any two devices. Communication between devices is limited to the number of connections supported by the S7-200 CPU or EM 277 modules. See Table 7-3 for the number of connections supported by the S7-200.

For MPI protocol, the S7-300 and S7-400 PLCs use the XGET and XPUT instructions to read and write data to the S7-200 CPU. For information about these instructions, refer to your S7-300 or S7-400 programming manual.

Figure 7-8 MPI Network

PROFIBUS Protocol

The PROFIBUS protocol is designed for high-speed communications with distributed I/O devices (remote I/O). There are many PROFIBUS devices available from a variety of manufacturers. These devices range from simple input or output modules to motor controllers and PLCs.

PROFIBUS networks typically have one master and several slave I/O devices. See Figure 7-9. The master device is configured to know what types of I/O slaves are connected and at what addresses. The master initializes the network and verifies that the slave devices on the network match the configuration. The master continuously writes output data to the slaves and reads input data from them.

Figure 7-9 PROFIBUS Network

When a DP master configures a slave device successfully, it then owns that slave device. If there is a second master device on the network, it has very limited access to the slaves owned by the first master.

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TCP/IP Protocol

The S7-200 can support TCP/IP Ethernet communication through the use of an Ethernet (CP 243--1) orInternet (CP 243--1 IT) expansion module. Table 7-4 shows the baud rate and number of connections supported by these modules.

Table 7-4 Number of Connections for the Ethernet (CP 243--1) and the Internet (CP 243--1 IT) Modules Module Ethernet (CP 243--1) Module Internet (CP 243--1 IT) Module 10 to 100 Mbaud Baud Rate Connections 8 general purpose connections 1 STEP 7--Micro/WIN connection Refer to the CP 243--1 Communications Processor for Industrial Ethernet Manual or the CP 243--1 IT Communications Processor for Industrial Ethernet and Information Technology Manual for additional information.

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TCP/IP Protocol

The S7-200 can support TCP/IP Ethernet communication through the use of an Ethernet (CP 243--1) orInternet (CP 243--1 IT) expansion module. Table 7-4 shows the baud rate and number of connections supported by these modules.

Table 7-4 Number of Connections for the Ethernet (CP 243--1) and the Internet (CP 243--1 IT) Modules Module Ethernet (CP 243--1) Module Internet (CP 243--1 IT) Module 10 to 100 Mbaud Baud Rate Connections 8 general purpose connections 1 STEP 7--Micro/WIN connection Refer to the CP 243--1 Communications Processor for Industrial Ethernet Manual or the CP 243--1 IT Communications Processor for Industrial Ethernet and Information Technology Manual for additional information.

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