高手请进来指点一下迷津！

[sunlightgz]

为什么我的串口程序在运行时，总出现“串口已打开”（单击command2时）和“设备未打开”（单击command1时）的错误？
其中command2.caption="打开串口"
command1.caption="关闭串口"

程序代码如：
Dim ytemp() As Byte
Dim stemp As String
Dim i As Integer


Private Sub Command2_Click()
MSComm1.CommPort = 1
MSComm1.Settings = "9600,N,8,1"
MSComm1.InputLen = 0
MSComm1.InBufferSize = 1024
MSComm1.OutBufferSize = 1024
MSComm1.InputMode = comInputModeBinary
MSComm1.PortOpen = True
MSComm1.InBufferCount = 0
MSComm1.OutBufferCount = 0
MSComm1.RThreshold = 1
If MSComm1.PortOpen = False Then
MSComm1.PortOpen = True
If Err Then
MsgBox "串口通讯失败！"
Exit Sub
End If

End If



End Sub

Private Sub Command1_Click()
MSComm1.PortOpen = False
Exit Sub


End Sub

Private Sub Form_Load()

End Sub

Private Sub MSComm1_OnComm()
With MSComm1
Select Case .CommEvent
Case comEvReceive
'接受

If MSComm1.InBufferCount > 0 Then
i = MSComm1.InBufferCount
ytemp = MSComm1.Input
stemp = StrConv(ytemp, vbFromUnicode)
Text1.Text = stemp
End If

End Sub

Private Sub Timer1_Timer()


'发送
stemp = Text2.Text
ytemp = StrConv(stemp, vbUnicode)
Debug.Print UBound(ytemp)
MSComm1.Output = ytemp

End Sub

[用户 昵称]

try close com first after form_load.