VB.NET串口通讯
发布时间:2020-12-16 22:27:56 所属栏目:大数据 来源:网络整理
导读:Mitsubishi公司的FX2N系列PLC与计算机之间的串口通讯,参考代码如下 mports System.IO.PortsPublic Class Form1 '使用WithEvents关键字声明一个通信端口对象 Dim WithEvents RS232 As SerialPort '初始化取得计算机中存在的可用串行通讯端口 Sub initializin
Mitsubishi公司的FX2N系列PLC与计算机之间的串口通讯,参考代码如下 mports System.IO.Ports Public Class Form1 '使用WithEvents关键字声明一个通信端口对象 Dim WithEvents RS232 As SerialPort '初始化取得计算机中存在的可用串行通讯端口 Sub initializing() For Each sp As String In SerialPort.GetPortNames() cmbCOM.Items.Add(sp) 'cmbCOM是ComboBox控件,该代码用来取得系统找到的所有串口名称 Next cmbCOM.Sorted = True '排序 cmbCOM.SelectedIndex = 0 '第一个是预设选项 End Sub '联机,使用正确的通讯参数建立一个通讯端口对象 Sub online() Try RS232 = New IO.Ports.SerialPort(cmbCOM.SelectedItem.ToString,9600,Parity.Even,7,StopBits.Two) 'RS232.Encoding = System.Text.Encoding.ASCII,如果系统支持中文,可以使用Encoding.Unicode编码方案 If Not RS232.IsOpen Then RS232.Open() Catch ex As Exception MsgBox("通讯端口打开错误!" & vbCrLf & "故障信息:" & vbCrLf & ex.Message,MsgBoxStyle.OkCancel) End Try End Sub '离线,关闭通讯端口 Sub offline() Try If RS232.IsOpen Then RS232.Close() : RS232 = Nothing '释放资源 Catch ex As Exception MsgBox("通讯端口关闭错误!" & vbCrLf & "故障信息:" & vbCrLf & ex.Message,MsgBoxStyle.OkCancel) End Try End Sub '通讯延时,通讯延时与串口处理数据时的ReadTimeout和WriteTimeout的含义是完全不同的 Sub TimeDelay(ByVal DT As Integer) Dim ET As Integer ET = Environment.TickCount() Do If Environment.TickCount() - ET >= DT Then Exit Do Application.DoEvents() '处理队列中的讯息 Loop End Sub '串口数据接收函数 Function DataReceive() As String Dim input As String,strfst As String DataReceive = Nothing input = RS232.ReadExisting() If input <> Nothing Then '以下代码用来判断接收的数据起始字符是STX(Chr(2))/ACK(Chr(6)),NAK/(Chr(21)) strfst = Asc(Microsoft.VisualBasic.Left(input,1)).ToString Select Case strfst Case "2" If rCheckSum(input) = "OKSUM" Then Return (input) If rCheckSum(input) = "ERSUM" Then Return "ERSUM" Case "6" Return Asc(input).ToString Case "21" Return Asc(input).ToString Case Else Return "ERCOM" '如果所选串口返回的未知数据,说明串口通讯故障/计算机连接到未知设备! End Select Else Return "ERCOM" '如果所选串口没有任何数据返回,说明串口通讯故障/PC Command ERROR! End If End Function '************************************************************** Private Sub Form1_Load(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles MyBase.Load initializing() btnoffline.Enabled = False stx.Text = "Chr(2)" cmd.Text = "0" End Sub Private Sub btnonline_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles btnonline.Click online() If RS232.IsOpen Then btnonline.Enabled = False If RS232.IsOpen Then btnoffline.Enabled = True End Sub Private Sub btnoffline_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles btnoffline.Click offline() btnoffline.Enabled = False btnonline.Enabled = True End Sub Private Sub btnEnd_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles btnEnd.Click If RS232 Is Nothing Then '判断是否已建立通信对象 End Else If RS232.IsOpen Then RS232.Close() '若已经打开,就将其关闭 End If End End Sub Private Sub btnSend_Click(ByVal sender As System.Object,ByVal e As System.EventArgs) Handles btnSend.Click Try If Not RS232 Is Nothing Then '判断是否已建立通信对象 Dim OutCmd As String Dim indat As String OutCmd = Nothing indat = RS232.ReadExisting() '使用.ReadExisting()方法清空缓冲区 If cmd.Text.Trim = "0" Then OutCmd = cmd.Text.Trim + address.Text.Trim + byten.Text.Trim + Chr(3) If cmd.Text.Trim = "1" Then OutCmd = cmd.Text.Trim + address.Text.Trim + byten.Text.Trim + data.Text.Trim + Chr(3) OutCmd = Chr(2) + OutCmd + tCheckSum(OutCmd) '发送命令调用CheckSum函数生成CheckSum字符串 RS232.Write(OutCmd) TimeDelay(300) indat = DataReceive() If indat = "ERCOM" Or indat = "ERSUM" Then MsgBox("通讯故障!PLC OFFLINE!!!/数据传输错误!!!") Else txtResult.Text += OutCmd + "->" + indat + vbCrLf txtResult.SelectionStart = txtResult.TextLength '将光标自动移至最下一位 txtResult.ScrollToCaret() '将光标自动移至最下一位 End If Else MsgBox("通信端口尚未打开!",MsgBoxStyle.OkCancel) End If Catch ex As Exception MsgBox("通讯端口发生故障!" & vbCrLf & "故障信息:" & vbCrLf & ex.Message) End Try End Sub '应用程序窗口关闭时的响应事件,如果RS232通讯已建立就将其关闭再退出 Private Sub Form1_FormClosing(ByVal sender As Object,ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing If RS232 Is Nothing Then '判断是否已建立通信对象 End Else If RS232.IsOpen Then RS232.Close() '若已经打开,就将其关闭 End If End End Sub End Class (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |