public UInt16  Cal_crc16(byte[] data, int size)
{

    UInt32 i = 0;
    UInt16 crc = 0;
    for (i = 0; i < size; i++)
    {
        crc = UpdateCRC16(crc, data[i]);
    }
    crc = UpdateCRC16(crc, 0);
    crc = UpdateCRC16(crc, 0);

    return (UInt16)(crc);
}
public UInt16  UpdateCRC16(UInt16  crcIn, byte  bytee)
{
    UInt32  crc = crcIn;
    UInt32  ins =(UInt32)bytee | 0x100;

    do
    {
        crc <<= 1;
        ins <<= 1;
        if ((ins & 0x100)==0x100 )
        {
            ++crc;
        }
        if ((crc & 0x10000)==0x10000)
        {
            crc ^= 0x1021;
        }
    }
    while (!((ins&0x10000)==0x10000) );
    return (UInt16 )crc;
}