进度更新2：在原程序的基础上加了一个文本框，一个按钮，可以在程序运行阶段改端口了。并且实现了对小灯状态的检测

代码：

Private Sub Command1_Click()
MSComm1.Output = "1"
End Sub

Private Sub Command2_Click()
MSComm1.Output = "0"
End Sub

Private Sub Command3_Click()
MSComm1.CommPort = Text1.Text
If MSComm1.PortOpen = False Then
MSComm1.PortOpen = True '打开串口
End If
End Sub

Private Sub MSComm1_OnComm()
Dim num As Integer
num = 0
num = CInt(MSComm1.Input)
Form1.Caption = num
If num = 1 Then
Command1.BackColor = RGB(0, 255, 0)
Command2.BackColor = RGB(255, 255, 255)
Else
Command1.BackColor = RGB(255, 255, 255)
Command2.BackColor = RGB(255, 0, 0)
End If
End Sub