code: public byte[] getMessage() {
          byte result[] = new byte[4];
  
          result[0] = (byte)(function >> 8);
          result[1] = (byte)(function & 0xFF);
          result[2] = (byte)(data >> 8);
          result[3] = (byte)(data & 0xFF);
  
          return result;
      }
docs: getMessage -- Create the DIAGNOSTICS message paylaod.
  @return message paylaod