VB.NET 串口读取 HEX 数据并插入到文本框中

Question

我想从连接在我的一个 COM 端口上的 UHF RFID 阅读器读取数据，数据应该是十六进制的，并且必须是一个完整的十六进制，应该粘贴在我制作的 windows 窗体应用程序的文本框中在 VB.NET 中。

请帮助我，我是 VB.NET 编程的新手。我需要一个 vb.net 代码来完成这项任务：

我的代码：

Public Class Form1

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
   For Each s In System.IO.Ports.SerialPort.GetPortNames() 
        ComboBox1.Items.Add(s)
    Next s

End Sub


Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    If ComboBox1.SelectedIndex = -1 Then
        MessageBox.Show("Please select a port")
        Exit Sub
    Else
        SerialPort1.BaudRate = 9600
        SerialPort1.DataBits = 8
        SerialPort1.Parity = IO.Ports.Parity.None
        SerialPort1.StopBits = IO.Ports.StopBits.One
        SerialPort1.PortName = ComboBox1.SelectedItem.ToString
        SerialPort1.Open()
    End If
End Sub

Private Shared buffer As String = ""

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

    Try
        Dim rcv As String = _SerialPort1.ReadExisting()
        buffer = String.Concat(buffer, rcv)


        Dim hexVal As Integer
        hexVal = Convert.ToInt32(rcv, 16) '16 specifies the base

        txtReceived.Text = hexVal

    Catch ex As Exception
    End Try

End Sub

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
    SerialPort1.Close()

End Sub

结束类

Answer 1

我明白你的问题..

一行

hexVal = Convert.ToInt32(c, 16) '16 specifies the base

正在尝试将字符转换为 int32，但该函数假设传入的值已经是十六进制，而您得到的答案完全错误。

顺便说一句，您的数据是 8 位二进制，而您的串行端口阅读器将每个 8 位读取为 char 类型。

你需要的是使用VB内置函数Hex，它接受一个整数/字节（在这种情况下是每个字符的ascii代码）并返回一个十六进制值作为字符串所以

Dim x As Integer = 15
Dim s As String = hex(x)

将“F”分配给字符串

一切顺利。但是，如果您想要一个 2 位的十六进制字符串，则需要检查返回的字符串是否只有一个字符，如果是，则在开头添加一个“0”。

那么，你的台词

Dim hexVal As Integer
hexVal = Convert.ToInt32(rcv, 16) '16 specifies the base
txtReceived.Text = hexVal

应该替换为..

Dim hexVal As string =""
For Each c As Char In rcv
    hexVal = heval & AsciiCharToHexSring(c)
Next
txtReceived.Text = hexVal

并添加此函数以转换字符并在必要时添加“0”..

Private Function AsciiCharToHexSring(s As Char) As String
    Dim hexdigit As String = Hex(Asc(s))
    If hexdigit.Length = 1 Then
        hexdigit = "0" & hexdigit
    End If
    Return hexdigit
End Function

如果您不需要每次都使用 2 位十六进制数字，只需删除 If..End If 块