Question

Dim MSComm1 As MSComm

on error goto cant_open_com1

MSComm1.CommPort = 1
MSComm1.Settings = "9600,N,8,1"
MSComm1.DTREnable = True
MSComm1.Handshaking = comRTS
MSComm1.InBufferSize = 12 + 1  ' +1 for the CR
MSComm1.RThreshold = MSComm1.InBufferSize
MSComm1.RTSEnable = True
MSComm1.InputLen = 0 ' read entire input buffer
MSComm1.InputMode = comInputModeText
MSComm1.NullDiscard = True
MSComm1.OutBufferSize = 0 ' not used, we don't write to the serial port
MSComm1.SThreshold = MSComm1.OutBufferSize
'MSComm1.ParityReplace = ?

MSComm1.PortOpen = True

控制传递给错误处理程序

Answer 1

当您说“控制传递给错误处理程序”时，您是否忘记添加Exit Sub？在您的评论中，您说您添加了新声明，但您仍然遇到问题？好吧，我刚刚运行了这段代码，打开端口没问题。

Private Sub Form_Load()

  Dim MSComm1 As New MSComm

  On Error GoTo cant_open_com1

  MSComm1.CommPort = 1
  MSComm1.Settings = "9600,N,8,1"
  MSComm1.DTREnable = True
  MSComm1.Handshaking = comRTS
  MSComm1.InBufferSize = 12 + 1
  MSComm1.RThreshold = MSComm1.InBufferSize
  MSComm1.RTSEnable = True
  MSComm1.InputLen = 0
  MSComm1.InputMode = comInputModeText
  MSComm1.NullDiscard = True
  MSComm1.OutBufferSize = 0
  MSComm1.SThreshold = MSComm1.OutBufferSize

  MSComm1.PortOpen = True

  Exit Sub

cant_open_com1:
    Debug.Print Err.Description

End Sub

Answer 2

不要在端口COM1上设置打印机。 COM1端口将被COM1端口中的打印机占用。使用Visual Basic MSCOMM组件时，您不需要任何打印机驱动程序。如果您在COM1端口中设置打印机。您可以使用以下代码。此代码不会受打印机设置的影响。

Visual Basic：为输出AS＃1打开“COM1”

为什么这个VB 6代码不会打开串口？

2 个答案: