仪表通讯中数字的几种表示方法

1. 用32位表示浮点数

 vb 16进制和浮点数互相转换的方法

'IEEE754 浮点数 http://www.doc88.com/p-9902813307216.html,  0.98=3F 7A E1 47
'http://lostphp.com/hexconvert/
Private Function SingleToHex(ByVal fValue As Single) As String
    Dim AA(3) As Byte
    Dim HexString As String
    Dim tmp As String
    CopyMemory ByVal VarPtr(AA(0)), ByVal VarPtr(fValue), 4
    For i = 3 To 0 Step -1
        tmp = CStr(Hex(AA(i)))
        If (Len(tmp) = 1) Then
            tmp = "0" & tmp
        End If
        HexString = HexString & tmp & " "
    Next
    SingleToHex = Left(HexString, Len(HexString) - 1)
End Function

'IEEE754 浮点数
Private Function HexToSingle(ByVal HexString As String) As Single
        Dim AA() As Byte
        Dim BB(3) As Byte
        Dim fValue As Single
        
        AA = HexStringToBytes(HexString)
        'reverse array
        BB(0) = AA(3)
        BB(1) = AA(2)
        BB(2) = AA(1)
        BB(3) = AA(0)
        CopyMemory ByVal VarPtr(fValue), ByVal VarPtr(BB(0)), 4
        HexToSingle = fValue
End Function

C#的方法

//4048F5C2 => 3.14            
string value = "4048F5C2";//16进制字符串

UInt32 x = Convert.ToUInt32(value, 16);//字符串转16进制32位无符号整数

 float fy = BitConverter.ToSingle(BitConverter.GetBytes(x), 0);//IEEE754 字节转换float


//3.14=>4048F5C2 
            var cc = BitConverter.GetBytes(fy);

            string HexStr= string.Empty;
            for (int i = 0; i < 4; i++)
            {
                HexStr = Convert.ToString(cc[i], 16).ToUpper() + HexStr;
            }

 

 

2.  约定固定小数位数, 比如3.56 ,就*100 =356,  取值时对应就除100

通讯时就取Hex(356)