用VB怎么做COM口通讯`

Private Sub Command1_Click()
MSComm1.Output = "123456"
End Sub

Private Sub Form_Load()
MSComm1.PortOpen = True
MSComm1.RThreshold = 1
MSComm1.SThreshold = 1
MSComm1.InputMode = comInputModeText
Text1 = ""
End Sub

Private Sub MSComm1_OnComm()
Select Case MSComm1.CommEvent
Case comEvSend
Text1 = "comEvSend"
Case comEvReceive
Text1 = "comEvReceive"
Case comEvCTS
Text1 = "comEvCTS"
Case comEvDSR
Text1 = "comEvDSR"
Case comEvCD
Text1 = "comEvCD"
Case comEvRing
Text1 = "comEvRing"
Case comEvEOF
Text1 = "comEvEOF"
End Select
End Sub

以下参考MSDN：
OnComm 常数
常数 值 描述
comEvSend 1 发送事件。
comEvReceive 2 接收事件。
comEvCTS 3 clear-to-send 线变化。
comEvDSR 4 data-set ready 线变化。
comEvCD 5 carrier d