Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
If SerialPort1.IsOpen = True Then SerialPort1.Close() '避免重复打开端口
SerialPort1.Open()
With SerialPort1
.ReadTimeout = 100
.WriteTimeout = 100
.BaudRate = 9600
.DataBits = 8
.StopBits = IO.Ports.StopBits.One
.Parity = IO.Ports.Parity.None
End Sub
初始化串口。再试试。