C# 读取西门子S7系列PLC教程及源码

创建 PLC 实例，连接和断开连接

若要创建驱动程序的实例，需要使用此构造函数：

public Plc(CpuType cpu, string ip, Int16 rack, Int16 slot)

CPU：这指定您要连接到的 CPU。支持的 CPU 包括：

public enum CpuType {S7200 = 0,S7300 = 10,S7400 = 20,S71200 = 30,S71500 = 40,
}

ip：指定 CPU 或外部以太网卡的 IP 地址
机架：它包含PLC的机架，您可以在Step7的硬件配置中找到
插槽：这是CPU的插槽，您可以在Step7的硬件配置中找到

例：

此代码为 IP 地址为 7.300.127.0 的 S0-1 plc 创建一个 Plc 对象，为 CPU 位于插槽 0 的机架 2 中的 plc 创建一个 Plc 对象：

Plc plc = new Plc(CpuType.S7300, "127.0.0.1", 0, 2);

连接到 PLC

public void Open()

例如，这行代码打开连接：

plc.Open();

断开与 PLC 的连接

public void Close()

例如，这将关闭连接：

plc.Close();

错误处理

任何方法都可能导致各种错误。您应该实现正确的错误处理。提供了和足够的错误消息。PlcExceptionPlcExceptionErrorCode

以下是错误的类型：

public enum ErrorCode
{NoError = 0,WrongCPU_Type = 1,ConnectionError = 2,IPAddressNotAvailable, WrongVarFormat = 10,WrongNumberReceivedBytes = 11, SendData = 20,ReadData = 30, WriteData = 50
}

检查 PLC 可用性

要检查 plc 是否可用（打开套接字），您可以使用该属性

public bool IsAvailable

当您检查此属性时，驱动程序将尝试连接到 plc，如果它可以连接，则返回 true，否则返回 false。

检查 PLC 连接

检查 plc 连接是微不足道的，因为您必须检查 PC 插座是否已连接，而且还要检查 PLC 是否仍连接在插座的另一侧。在这种情况下，您必须检查的属性是：

public bool IsConnected

在调用方法 Open（）并且结果成功后，可以检查此属性，以检查连接是否仍处于活动状态。

读取字节/写入字节

该库提供了几种读取变量的方法。基本和最常用的是ReadBytes。

public byte[] ReadBytes(DataType dataType, int db, int startByteAdr, int count)public void WriteBytes(DataType dataType, int db, int startByteAdr, byte[] value)

这将从给定内存位置读取您指定的所有字节。此方法会自动处理多个请求，以防字节数超过单个请求中可以传输的最大字节数。

数据类型：您必须使用枚举数据类型指定内存位置

public enum DataType
{Input = 129,Output = 130,Memory = 131,DataBlock = 132,Timer = 29,Counter = 28
}

db：数据类型的地址，例如如果要读取 DB1，此字段为 “1”;如果要读取 T45，则此字段为 45。
startByteAdr：要读取的第一个字节的地址，例如，如果要读取 DB1。DBW200，这是200。
计数：包含要读取的字节数。
值[ ]：要从PLC读取的字节数组。

例：此方法读取 DB200 的前 1 个字节：

var bytes = plc.ReadBytes(DataType.DataBlock, 1, 0, 200);

读写解码

此方法允许根据提供的varType读取和接收已解码的结果。如果您读取多个相同类型的字段（例如 20 个连续的 DBW），这将非常有用。如果指定 VarType.Byte，则它具有与 ReadBytes 相同的功能。

public object Read(DataType dataType, int db, int startByteAdr, VarType varType, int varCount)public void Write(DataType dataType, int db, int startByteAdr, object value)

数据类型：您必须使用枚举数据类型指定内存位置

public enum DataType
{Input = 129,Output = 130,Memory = 131,DataBlock = 132,Timer = 29,Counter = 28
}

db：数据类型的地址，例如如果要读取 DB1，此字段为 “1”;如果要读取 T45，则此字段为 45。
startByteAdr：要读取的第一个字节的地址，例如，如果要读取 DB1。DBW200，这是200。
varType：指定要转换字节的数据。

public enum VarType
{Bit,Byte,Word,DWord,Int,DInt,Real,String,StringEx,Timer,Counter
}

count：包含要读取的变量数。
值：要写入 PLC 的值数组。它可以是单个值或数组，只需记住该类型是唯一的（例如双精度数组、整数数组、短整型数组等）。

例：此方法读取 DB20 的前 1 个 DWord：

var dwords = plc.Read(DataType.DataBlock, 1, 0, VarType.DWord, 20);

读取单个变量/写入单个变量

此方法通过解析字符串并返回正确的结果，从 plc 读取单个变量。虽然这是最简单的入门方法，但效率非常低，因为驱动程序为每个变量发送 TCP 请求。

public object Read(string variable)public void Write(string variable, object value)

variable: specify the variable to read by using strings like “DB1.DBW20”, “T45”, “C21”, “DB1.DBD400”, etc.

Example: This reads the variable DB1.DBW0. The result must be cast to ushort to get the correct 16-bit format in C#.

ushort result = (ushort)plc.Read("DB1.DBW0");

读取结构/编写结构

This method reads all the bytes from a specified DB needed to fill a struct in C#, and returns the struct that contains the values. It is recommended to use when you want to read many variables in a single data block in some continuous memory range.

The "read struct" and "write struct" methods do not support strings.

public object ReadStruct(Type structType, int db, int startByteAdr = 0)public void WriteStruct(object structValue, int db, int startByteAdr = 0)

structType: Type of the struct to be read, for example: typeOf(MyStruct))
db: index of the DB to read
startByteAdr: specified the first address of the byte to read (the default is zero).

Then add a struct into your .Net application that is similiar to the DB in the plc:

public struct testStruct
{public bool varBool0;public bool varBool1;public bool varBool2;public bool varBool3;public bool varBool4;public bool varBool5;public bool varBool6;public byte varByte0;public byte varByte1;public ushort varWord0;public float varReal0;public bool varBool7;public float varReal1;public byte varByte2;public UInt32 varDWord;
}

then add the code to read or write the complete struct

// reads a struct from DataBlock 1 at StartAddress 0
testStruct myTestStruct = (testStruct) plc.ReadStruct(typeof(testStruct), 1, 0);

Read a class / Write a class

This method reads all the bytes from a specified DB needed to fill a class in C#. The class is passed as reference and values are assigned by using reflection. It is recommended to use when you want to read many variables in a single data block in some continuous memory range.

The "read class" and "write class" methods do not support strings.

public void ReadClass(object sourceClass, int db, int startByteAdr = 0)public void WriteClass(object classValue, int db, int startByteAdr = 0)

sourceClass: instance of the class that you want to assign the values
db: index of the DB to read
startByteAdr: specified the first address of the byte to read (the default is zero).

Then add a struct into your .Net application that is similiar to the DB in the plc:

public class TestClass
{public bool varBool0 { get; set;}public bool varBool1 { get; set;}public bool varBool2 { get; set;}public bool varBool3 { get; set;}public bool varBool4 { get; set;}public bool varBool5 { get; set;}public bool varBool6 { get; set;}public byte varByte0 { get; set;}public byte varByte1 { get; set;}public ushort varWord0 { get; set;}public float varReal0 { get; set;}public bool varBool7 { get; set;}public float varReal1 { get; set;}public byte varByte2 { get; set;}public UInt32 varDWord { get; set;}
}

then add the code to read or write the complete class

// reads a class from DataBlock 1, startAddress 0
TestClass myTestClass = new TestClass();
plc.ReadClass(myTestClass, 1, 0);

Read multiple variables

This method reads multiple variables in a single request. The variables can be located in the same or in different data blocks.

public void Plc.ReadMultibleVars(List<DataItem> dataItems);

List<>: you have to specify a list of DataItem which contains all data items you want to read

Example: this method reads several variables from a data block

define the data items first

private static DataItem varBit = new DataItem()
{DataType = DataType.DataBlock,VarType = VarType.Bit,DB = 83,BitAdr = 0,Count = 1,StartByteAdr = 0,Value = new object()
};private static DataItem varByteArray = new DataItem()
{DataType = DataType.DataBlock,VarType = VarType.Byte,DB = 83,BitAdr = 0,Count = 100,StartByteAdr = 0,Value = new object()
};private static DataItem varInt = new DataItem()
{DataType = DataType.DataBlock,VarType = VarType.Int,DB = 83,BitAdr = 0,Count = 1,StartByteAdr = 102,Value = new object()
};private static DataItem varReal = new DataItem()
{DataType = DataType.DataBlock,VarType = VarType.Real,DB = 83,BitAdr = 0,Count = 1,StartByteAdr = 112,Value = new object()
};private static DataItem varString = new DataItem()
{DataType = DataType.DataBlock,VarType = VarType.StringEx,DB = 83,BitAdr = 0,Count = 20,         // max lengt of stringStartByteAdr = 116,Value = new object()
};private static DataItem varDateTime = new DataItem()
{DataType = DataType.DataBlock,VarType = VarType.DateTime,DB = 83,BitAdr = 0,Count = 1,StartByteAdr = 138,Value = new object()
};

Then define a list where the DataItems will be stored in

private static List<DataItem> dataItemsRead = new List<DataItem>();

add the data items to the list

dataItemsRead.Add(varBit);
dataItemsRead.Add(varByteArray);
dataItemsRead.Add(varInt);
dataItemsRead.Add(varReal);
dataItemsRead.Add(varString);
dataItemsRead.Add(varDateTime);

open the connection to the plc and read the items at once

myPLC.Open();// read the list of variables
myPLC.ReadMultipleVars(dataItemsRead);// close the connection
myPLC.Close();// access the values of the list
Console.WriteLine("Int:" + dataItemsRead[2].Value);

Write multiple variables

This method writes multiple variables in a single request.

public void Plc.Write(Array[DataItem] dataItems);

Array[] you have to specifiy an array of DataItem which contains all the items you want to write

Example: this method writes multiple variables into one data block

define the data items

 private static DataItem varWordWrite = new DataItem()
{DataType = DataType.DataBlock,VarType = VarType.Word,DB = 83,BitAdr = 0,Count = 1,StartByteAdr = 146,Value = new object()
};private static DataItem varIntWrite = new DataItem()
{DataType = DataType.DataBlock,VarType = VarType.Int,DB = 83,BitAdr = 0,Count = 1,StartByteAdr = 148,Value = new object()
};private static DataItem varDWordWrite = new DataItem()
{DataType = DataType.DataBlock,VarType = VarType.DWord,DB = 83,BitAdr = 0,Count = 1,StartByteAdr = 150,Value = new object()
};private static DataItem varDIntWrite = new DataItem()
{DataType = DataType.DataBlock,VarType = VarType.DInt,DB = 83,BitAdr = 0,Count = 1,StartByteAdr = 154,Value = new object()
};private static DataItem varRealWrite = new DataItem()
{DataType = DataType.DataBlock,VarType = VarType.Real,DB = 83,BitAdr = 0,Count = 1,StartByteAdr = 158,Value = new object()
};private static DataItem varStringWrite = new DataItem()
{DataType = DataType.DataBlock,VarType = VarType.StringEx,DB = 83,BitAdr = 0,Count = 20,StartByteAdr = 162,Value = new object()
};

Asign the values to the data items. Be aware to use the correct data conversion for the variables to fit into the S7-data types

// asign values to the variable to be written
varWordWrite.Value = (ushort)67;
varIntWrite.Value = (ushort)33;
varDWordWrite.Value = (uint)444;
varDIntWrite.Value = 6666;
varRealWrite.Value = 77.89;
varStringWrite.Value = "Writting";

Then define a list to store the data items and add the created items to the list

private static List<DataItem> dataItemsWrite = new List<DataItem>();// add data items to list of data items to write
dataItemsWrite.Add(varWordWrite);
dataItemsWrite.Add(varIntWrite);
dataItemsWrite.Add(varDWordWrite);
dataItemsWrite.Add(varDIntWrite);
dataItemsWrite.Add(varRealWrite);
dataItemsWrite.Add(varStringWrite);

Finally open a connection to the plc and write the items at once. Use to convert the list into an array..ToArray()

// open the connection
myPLC.Open();// write the items
myPLC.Write(dataItemsWrite.ToArray());// close the connection
myPLC.Close();

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