通讯埠专题实验

1、通訊埠專題實驗1. 迴路測試：p3-23 LoopTest2. 迴路測試-使用SerialPort控制項：p3-33 LoopTest23. 數位輸出：p3-37 comDO4. 數位輸入：p3-47 PinEvent-Timer5. 自動偵測與事件處理：p3-57 AutoReceive6. 自動傳送資料：p3-68 AutoSendReceive7. 事件處理與執行緒：p3-75 comEvent-First8. 使用DataReceived事件：p3-85 comEvent9. 委派處理：p3-90 comEvent210. 使用PinChanged事件測試數位輸入：p3-90 comD

2、I11. 計時器與DoEvents()事件進階應用：P3-101 TimerDoevent12. 建立執行緒：p3-106 AutoReceive-Thread程式設計重點解說在類別模組上方引入通訊埠物件參考ImportsImports System.Text在類別模組內第一行宣告通訊埠物件Dim RS232 As SerialPort在Form_Load事件內替ComPort下拉組合方塊加入選項資料 For Each sp As String In SerialPort.GetPortNames Next cmbCOM.Sorted = True '排序 cmbCOM.Selecte

3、dIndex = 0 '第一個是預設選項開啟通訊埠程式碼Dim mBaudRate As Integer Dim mParity As Parity Dim mDataBit As Integer Dim mStopbit As StopBits Dim mPortName As String'欲開啟的通訊埠 mBaudRate = 9600 '通訊速度 mParity = Parity.None '同位位元檢查設定 mDataBit = 8 '資料位元設定值 mStopbit = StopBits.One '停止位元設定值 '建立一個通

4、訊埠物件 RS232 = New SerialPort(mPortName, mBaudRate, mParity, mDataBit, mStopbit) RS232.Encoding = Encoding.Unicode '設定編碼方式為Unicode，以便能顯示中文 If Not RS232.IsOpen Then '尚未開啟 RS232.Open() '開啟通訊埠 btnSend.Enabled = True '致能傳送按鈕 btnReceive.Enabled = True Else MsgBox("通訊埠開啟錯誤(通訊埠已被開啟)"

5、;, MsgBoxStyle.Critical Or MsgBoxStyle.OkCancel) End End If傳送資料RS232.Write(txtSend.Text)接收資料Dim InString As String InString = "" Try RS232.ReadTimeout = 1000 InString = RS232.ReadExisting() If InString Is Nothing Then Exit Sub Else txtReceive.Text = InString End If Catch ex As Exception Me

6、ssageBox.Show("讀取錯誤：" + ex.ToString, "錯誤通知", MessageBoxButtons.OK, MessageBoxIcon.Exclamation) End Try關閉通訊埠程式碼If RS232 Is Nothing OrElse Not RS232.IsOpen Then '尚未開啟 MsgBox("通訊埠尚未開啟", MsgBoxStyle.Critical Or MsgBoxStyle.OkCancel) Else RS232.Close() btnSend.Enabled =

7、False btnReceive.Enabled = False End If結束程式If Not RS232 Is Nothing Then '判斷是否已建立通訊物件 If RS232.IsOpen Then RS232.Close() '若已開啟，就將其關閉 End If End數位輸出測試預設輸出腳位為低RS232.DtrEnable = False RS232.RtsEnable = False以按鈕事件改變腳位RS232.DtrEnable = Not RS232.DtrEnable '變更狀態 If RS232.DtrEnable Then picDTR.I

8、mage = picGreen.Image '變更為綠色圖示 Else picDTR.Image = picRed.Image '變更為紅色圖示 End If RS232.RtsEnable = Not RS232.RtsEnable '變更狀態 If RS232.RtsEnable Then picRTS.Image = picGreen.Image '變更為綠色圖示 Else picRTS.Image = picRed.Image '變更為紅色圖示 End If數位輸入測試 搭配電路測試須加入 Timer控制項當開啟ComPort時同步啟動Timer

9、If Not RS232.IsOpen Then '尚未開啟 RS232.Open() '開啟通訊埠 Timer1.Enabled = True '啟動計時器 Else MsgBox("通訊埠開啟錯誤(通訊埠已被開啟)", MsgBoxStyle.Critical Or MsgBoxStyle.OkCancel) End End If加入Timer定時事件以定時偵測是否有資料輸入狀況Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) H

10、andles Timer1.Tick If RS232.DsrHolding Then 'DSR腳位為高電位狀態 picDSR.Image = picON.Image Else picDSR.Image = picOFF.Image End If If RS232.CtsHolding Then 'CTS腳位為高電位狀態 picCTS.Image = picON.Image Else picCTS.Image = picOFF.Image End If If RS232.CDHolding Then 'CD腳位為高電位狀態 picDCD.Image = picON.Im

11、age Else picDCD.Image = picOFF.Image End If End Sub自動讀取傳入的字串須加入 Timer控制項當開啟ComPort時同步啟動Timer加入Timer定時事件以定時偵測是否有資料輸入狀況Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick Dim InString As String InString = "" Try RS232.ReadTimeout = 1000 InS

12、tring = RS232.ReadExisting() If InString.Length = 0 Then '若無資料則跳出 Exit Sub Else txtReceive.Text += InString '若有資料則加到接收的文字框 End If Catch ex As Exception MessageBox.Show("讀取錯誤：" + ex.ToString, "錯誤通知", MessageBoxButtons.OK, MessageBoxIcon.Exclamation) End Try End Sub手動傳送字串Private Sub btnSend_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSend.Click RS232.Write(txtSend.Text) End Sub自動傳送字串 當在輸出文字方塊按下Enter 時選用輸出文字方之事件程序 KeyPress事件Private Su