VB编写的Modbus RTU协议通讯源程序

1、VB编写的Modbus RTU协议通讯源程序 sunwu 建议删除该贴! | 收藏 | 回复 | 修改 | 2005-12-09 12:37:09 楼主 modbus rtu协议可以算是一种事实上的工业标准协议，为许多仪表、PLC等所支持。以前有几个用户问如何使用VB编程来与我们的KND-K3系列PLC通讯，于是整了一个demo程序。这次把这个demo共享，希望能给大家一点帮助。 1） 模块文件：modCRC，其中包含了CRC校验的函数。 'data 待校验的数组名称 'no 数组中元素个数 'btLoCRC 算出的CRC高字节 'btHiCRC 算出的CRC低

2、字节 Public Function CalCRC16Fast(data() As Byte, no As Integer, btLoCRC As Byte, btHiCRC As Byte) As String Dim CL As Byte, CH As Byte '多项式码&HA001 Dim SaveHi As Byte, SaveLo As Byte Dim i As Integer Dim Flag As Integer btHiCRC = &HFF btLoCRC = &HFF CL = &H1 CH = &HA0 For i = 0

3、 To (no - 1) btHiCRC = btHiCRC Xor data(i) '每一个数据与CRC寄存器进行异或 For Flag = 0 To 7 SaveHi = btLoCRC SaveLo = btHiCRC btLoCRC = btLoCRC 2 '高位右移一位 btHiCRC = btHiCRC 2 '低位右移一位 If (SaveHi And &H1) = &H1) Then '如果高位字节最后一位为1 btHiCRC = btHiCRC Or &H80 '则低位字节右移后前面补1 End If '否

4、则自动补0 If (SaveLo And &H1) = &H1) Then '如果LSB为1，则与多项式码进行异或 btLoCRC = btLoCRC Xor CH btHiCRC = btHiCRC Xor CL End If Next Flag Next i Dim ReturnData(1) As Byte ReturnData(0) = btHiCRC 'CRC高位 ReturnData(1) = btLoCRC 'CRC低位 CalCRC16Fast = ReturnData End Function Public Function CalCR

5、C16Tbl(data() As Byte, no As Integer, btLoCRC As Byte, btHiCRC As Byte) As String Dim btLoCRC As Byte Dim btHiCRC As Byte btLoCRC = &HFF btHiCRC = &HFF Dim i As Integer Dim iIndex As Long For i = 0 To (no - 1) iIndex = btHiCRC Xor data(i) btHiCRC = btLoCRC Xor GetCRCLo(iIndex) '低位处理 btLo

6、CRC = GetCRCHi(iIndex) '高位处理 Next i Dim ReturnData(1) As Byte ReturnData(0) = btHiCRC 'CRC高位 ReturnData(1) = btLoCRC 'CRC低位 CalCRC16Tbl = ReturnData End Function 'CRC低位字节值表 Function GetCRCLo(Ind As Long) As Byte GetCRCLo = Choose(Ind + 1, _ &H0, &HC1, &H81, &H40, &

7、;H1, &HC0, &H80, &H41, &H1, &HC0, _ &H80, &H41, &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, _ &H0, &HC1, &H81, &H40, &H0, &HC1, &H81, &H40, &H1, &HC0, _ &H80, &H41, &H1, &HC0, &H

8、80, &H41, &H0, &HC1, &H81, &H40, _ &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, &H0, &HC1, _ &H81, &H40, &H1, &HC0, &H80, &H41, &H1, &HC0, &H80, &H41, _ &H0, &HC1, &H81, &H40, &H1

9、, &HC0, &H80, &H41, &H0, &HC1, _ &H81, &H40, &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, _ &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, &H1, &HC0, _ &H80, &H41, &H0, &HC1, &H81,

10、 &H40, &H0, &HC1, &H81, &H40, _ &H1, &HC0, &H80, &H41, &H1, &HC0, &H80, &H41, &H0, &HC1, _ &H81, &H40, &H1, &HC0, &H80, &H41, &H0, &HC1, &H81, &H40, _ &H0, &HC1, &H81, &H40, &H1, &

11、amp;HC0, &H80, &H41, &H1, &HC0, _ &H80, &H41, &H0, &HC1, &H81, &H40, &H0, &HC1, &H81, &H40, _ &H1, &HC0, &H80, &H41, &H0, &HC1, &H81, &H40, &H1, &HC0, _ &H80, &H41, &H1, &HC0, &H80, &a

12、mp;H41, &H0, &HC1, &H81, &H40, _ &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, &H1, &HC0, _ &H80, &H41, &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, _ &H0, &HC1, &H81, &H40, &H0, &

13、;HC1, &H81, &H40, &H1, &HC0, _ &H80, &H41, &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, _ &H1, &HC0, &H80, &H41, &H0, &HC1, &H81, &H40, &H1, &HC0, _ &H80, &H41, &H0, &HC1, &H81, &

14、H40, &H0, &HC1, &H81, &H40, _ &H1, &HC0, &H80, &H41, &H1, &HC0, &H80, &H41, &H0, &HC1, _ &H81, &H40, &H0, &HC1, &H81, &H40, &H1, &HC0, &H80, &H41, &H0, &HC1, &H81, &H40, &H1, &HC0,

15、 &H80, &H41, &H1, &HC0, &H80, &H41, &H0, &HC1, &H81, &H40) End Function 'CRC高位字节值表 Function GetCRCHi(Ind As Long) As Byte GetCRCHi = Choose(Ind + 1, _ &H0, &HC0, &HC1, &H1, &HC3, &H3, &H2, &HC2, &HC6, &H6, &H7, &

16、amp;HC7, &H5, &HC5, &HC4, &H4, &HCC, &HC, &HD, &HCD, &HF, &HCF, &HCE, &HE, &HA, &HCA, &HCB, &HB, &HC9, &H9, &H8, &HC8, &HD8, &H18, &H19, &HD9, &H1B, &HDB, &HDA, &H1A, &H1E, &HDE, &

17、amp;HDF, &H1F, &HDD, &H1D, &H1C, &HDC, &H14, &HD4, &HD5, &H15, &HD7, &H17, &H16, &HD6, &HD2, &H12, &H13, &HD3, &H11, &HD1, &HD0, &H10, &HF0, &H30, &H31, &HF1, &H33, &HF3, &HF2, &H32, &

18、amp;H36, &HF6, &HF7, &H37, &HF5, &H35, &H34, &HF4, &H3C, &HFC, &HFD, &H3D, &HFF, &H3F, &H3E, &HFE, &HFA, &H3A, &H3B, &HFB, &H39, &HF9, &HF8, &H38, &H28, &HE8, &HE9, &H29, &HEB, &H2B, &

19、amp;H2A, &HEA, &HEE, &H2E, &H2F, &HEF, &H2D, &HED, &HEC, &H2C, &HE4, &H24, &H25, &HE5, &H27, &HE7, &HE6, &H26, &H22, &HE2, &HE3, &H23, &HE1, &H21, &H20, &HE0, &HA0, &H60, _ &H61, &HA1,

20、 &H63, &HA3, &HA2, &H62, &H66, &HA6, &HA7, &H67, &HA5, &H65, &H64, &HA4, &H6C, &HAC, &HAD, &H6D, &HAF, &H6F, &H6E, &HAE, &HAA, &H6A, &H6B, &HAB, &H69, &HA9, &HA8, &H68, &H78, &HB8,

21、 &HB9, &H79, &HBB, &H7B, &H7A, &HBA, &HBE, &H7E, &H7F, &HBF, &H7D, &HBD, &HBC, &H7 C, &HB4, &H74, &H75, &HB5, &H77, &HB7, &HB6, &H76, &H72, &HB2, &HB3, &H73, &HB1, &H71, &H70, &HB0

22、, &H50, &H90, &H91, &H51, &H93, &H53, &H52, &H92, &H96, &H56, &H57, &H97, &H55, &H95, &H94, &H54, &H9C, &H5C, &H5D, &H9D, &H5F, &H9F, &H9E, &H5E, &H5A, &H9A, &H9B, &H5B, &H99, &H59

23、, &H58, &H98, &H88, &H48, &H49, &H89, &H4B, &H8B, &H8A, &H4A, &H4E, &H8E, &H8F, &H4F, &H8D, &H4D, &H4C, &H8C, &H44, &H84, &H85, &H45, &H87, &H47, &H46, &H86, &H82, &H42, &H43, &H83

24、, &H41, &H81, &H80, &H40) End Function 2）窗体：FORM1，上面放置的控件如下： Begin VB.Form frmCom Caption = "Form1" ClientHeight = 8235 ClientLeft = 3885 ClientTop = 2250 ClientWidth = 6810 LinkTopic = "Form1" ScaleHeight = 8235 ScaleWidth = 6810 Begin VB.TextBox txtReceive 注：放置接

25、收上来的IB0数据 Height = 495 Left = 1200 TabIndex = 2 Top = 2280 Width = 1335 End Begin VB.CommandButton Command1 Caption = "读取IB0" Height = 495 Left = 2760 TabIndex = 1 Top = 2280 Width = 1695 End Begin VB.CommandButton cmdSDO Caption = "置位Q1.1" Height = 495 Left = 2160 TabIndex = 0 T

26、op = 3720 Width = 1575 End Begin MSCommLib.MSComm ComK3 Left = 480 Top = 1080 _ExtentX = 1005 _ExtentY = 1005 _Version = 393216 DTREnable = -1 'True End End Form_Load事件，在此主要是实现了打开并初始化串口 Private Sub Form_Load() With ComK3 .CommPort = 1 .Settings = "19200,N,8,1" .InputMode = comInputMode

27、Binary '二进制收发 .InBufferSize = 512 .OutBufferSize = 512 If (Not .PortOpen) Then .PortOpen = True End With End Sub Form_UnLoad事件，在此主要是关闭串口 Private Sub Form_Unload(Cancel As Integer) If (ComK3.PortOpen) Then ComK3.PortOpen = False End If End Sub “置位Q1.1”按钮单击事件 '设置Q1.1为1 Private Sub cmdSDO_Click() Dim btSend(8) As Byte btSend(0) = &H1 '目标站号 btSend(1) = &H5 '功能码 btSend(2) = &H0 'Q1.1地址（0009）高字节 btSend(3) = &H9 'Q1.1地址（0009）低字节 btSend(4) = &HFF '强制值高字节 btSend(5) = &H0 '强制值低字节 Dim crc