void crc(unsigned char msgData[],byte *lowbyte,byte *highbyte)
{
  unsigned short Polynom = 0x8408;
  unsigned short Register = 0x0000;
  unsigned short temp = 0x0000;

  // loop through the entire array of bytes
	  for( int i = 0; i < sizeof(msgData); i++ )
	  {
		temp = msgData[i];

		// shift all 8 data bits once
		for( int y = 0; y < 8; y++ )
		{
			if ( ( ( Register ^ temp ) & 0x01 ) == 0x01 )
			{
				Register >>= 1;
				Register ^= Polynom;
			}
			else
			{
				Register >>= 1;
			}
			temp >>= 1; // shift data 1 bit right, dividing it by 2

		} // end of inner for loop (bit shift loop)
	  } // end of outer for loop (data loop)

  // now we have got our overall 2-byte CRC "Checksum" number
  *lowbyte = (byte) ( Register / 256 );
  *highbyte = (byte) ( Register % 256 );

}