我想请教一下，在读取电子称的值得时候，如何读取。我没有搞过这个东东，看了一下别人写的代码，我看不明白，请高手指点一下，帮我解释一下。代码是这样的：(重点帮我分析一下红色字体的代码，我有点看不懂）。
Private Sub GetWeight_Value()
    On Error Resume Next
    Dim BytesReceived() As Byte
    Dim buffer As String
    Dim HData As String
    Dim i As Integer
                buffer = Comm1.Input                  '接收数据至字符串中
            BytesReceived() = buffer                '将数据转入Byte数组中
             For i = 0 To UBound(BytesReceived)      '显示结果以十六进制显示
                If Len(Hex(BytesReceived(i))) = 1 Then
                    HData = HData & "0" & Hex(BytesReceived(i))
                Else
                    HData = HData & Hex(BytesReceived(i))
                End If
                Recievedata = HData
                          Next   
    Call Calculatescale
End Sub
Public Sub Calculatescale()
    Dim a, b, c, d, e As Integer
    e = Mid(Recievedata, 18, 1)
    a = Mid(Recievedata, 20, 1)
    b = Mid(Recievedata, 24, 1)
    c = Mid(Recievedata, 26, 1)
    d = Mid(Recievedata, 28, 1)
    Weight_value = (e * 10000 + a * 1000 + b * 100 + c * 10 + d * 1) / 1000
    Weight_value = Format(Weight_value, "0.0000")
        Comm1.OutBufferCount = 0 '清除发送缓冲区
    Comm1.InBufferCount = 0 '清除接收缓冲区
    Comm1.PortOpen = False
End Sub

你说的那个我看过，我就是不知道这个   
    e = Mid(Recievedata, 18, 1)
    a = Mid(Recievedata, 20, 1)
    b = Mid(Recievedata, 24, 1)
    c = Mid(Recievedata, 26, 1)
    d = Mid(Recievedata, 28, 1) ，为什么读18,20,24,26,28这几位？
还有这个 Weight_value = (e * 10000 + a * 1000 + b * 100 + c * 10 + d * 1) / 1000
乘10000,1000,100,10,1的原因？