Question

我正在尝试创建一个应用程序，使用VB .NET显示来自Arduino的水分传感器值。我想在Label1.Text中显示传感器值，但似乎并不总是显示正确的值。

我还试图将值显示给RichTextBox，它可以显示正确的值。例如，如果读取值为1023，则RichTextBox1中显示的值为1023，但Label1中的值为23，或023，有时为3.

对此有何帮助？

Private Sub SerialPort1_DataReceived(ByVal sender As System.Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
    ReceivedText(SerialPort1.ReadExisting())
End Sub

Private Sub ReceivedText(ByVal [text] As String)
    If Me.RichTextBox1.InvokeRequired Then
        Dim x As New SetTextCallBack(AddressOf ReceivedText)
        Me.Invoke(x, New Object() {(text)})
    Else
        RichTextBox1.Text &= [text]
        Label1.Text = Val([text])
    End If
End Sub

Answer 1

为什么使用Val设置Text的{{1}}属性？

Label1将字符串中包含的数字作为数字值返回，并停止在第一个字符处读取字符串，该字符串无法识别为数字的一部分。

例如：

Val

如果您收到读取值为字符串...

Dim valResult As Double 
' The following line of code sets valResult to 2457.
valResult = Val("2457")
' The following line of code sets valResult to 2457.
valResult = Val(" 2 45 7")
' The following line of code sets valResult to 24.
valResult = Val("24 and 57")

Answer 2

所以我找到了解决问题的方法。我使用了ReadLine（）而不是ReadExisting（）并进行了一些字符串操作。

Private Sub SerialPort1_DataReceived(ByVal sender As System.Object, ByVal e As System.IO.Ports.SerialDataReceivedEventArgs) Handles SerialPort1.DataReceived
    readbuffer = SerialPort1.ReadLine()
    Me.Invoke(New EventHandler(AddressOf ReceivedText))
End Sub

Public Sub ReceivedText(ByVal sender As Object, ByVal e As System.EventArgs)
    Dim read As Decimal
    read = readbuffer.Replace(vbCr, "").Replace(vbLf, "")
    Label1.Text = read
End Sub

使用VB .NET显示Arduino的传感器值

2 个答案: