从modbus接收到的数据，转为浮点数：

float f = GetFloat(registerBuffer[0], registerBuffer[1]);

public static float GetFloat(ushort P1, ushort P2)
        {
            int intSign, intSignRest, intExponent, intExponentRest;
            float faResult, faDigit;
            intSign = P1 / 32768;
            intSignRest = P1 % 32768;
            intExponent = intSignRest / 128;
            intExponentRest = intSignRest % 128;
            faDigit = (float)(intExponentRest * 65536 + P2) / 8388608;
            faResult = (float)Math.Pow(-1, intSign) * (float)Math.Pow(2, intExponent - 127) * (faDigit + 1);
            return faResult;
        }

将浮点数转为modbus需要的无符号短整数：

            float fff = float.Parse(floattxt.Text);
            string d = BitConverter.ToString(BitConverter.GetBytes(fff).Reverse().ToArray()).Replace("-", "");
            Console.WriteLine(d);
            
            ushort ss1 = Convert.ToUInt16(d.Substring(0,4),16);
            ushort ss2 = Convert.ToUInt16(d.Substring(3, 4), 16);