def packMessage(DeviceID, Offset, dataLength=None,
                Byte0=None, Byte1=None, Byte2=None, Byte3=None,
                Word0=None, Word1=None, DWord0=None):

    Bytes = [Byte0, Byte1, Byte2, Byte3]

    #check if the values to be used are in range
    if Offset >= 2**16:
        raise ValueError
    else:
        Offset_low = Offset & 0x00FF
        Offset_high = Offset & 0xFF00 >> 8

    if dataLength is not None and not 1 <= dataLength <= 4:
        raise ValueError

    #split bigger data to bytes and check the data length
    if DWord0 is not None:
        if 0 <= DWord0 <= 2**32:
            Bytes[0] = DWord0 & 0xFF
            Bytes[1] = (DWord0 & 0xFF00) >> 8
            Bytes[2] = (DWord0 & 0xFF0000) >> 16
            Bytes[3] = (DWord0 & 0xFF000000) >> 24
            length = 4
        else:
            raise ValueError
    elif Word0 is not None:
        if 0 <= Word0 <= 2**16:
            Bytes[0] = Word0 & 0xFF
            Bytes[1] = (Word0 & 0xFF00) >> 8
        else:
            raise ValueError
        if Word1 is not None:
            if 0 <= Word0 <= 2**16:
                Byte2 = Word1 & 0xFF
                Byte3 = (Word1 & 0xFF00) >> 8
                length = 4
            else:
                raise ValueError
        else:
            Word1 = 0
            Byte2 = Byte3 = 0
            length = 2
    else:
        for i in range(len(Bytes)):
            if Bytes(i) is not None:
                length = i
            else:
                Bytes[i] = 0

    #if no length given take calculated length
    if dataLength is None:
        dataLength = length

    #return the Message
    return bytearray([DeviceID, dataLength, Offset_low,
                      Offset_high, Bytes[0], Bytes[1], Bytes[2], Bytes[3]])

if Byte0 is not None:
    if Byte1 is not None:
        if Byte2 is not None:
            if Byte3 is not None:
                length = 4
            else:
                Byte3 = 0
        else:
            length = 3
            Byte2 = 0
            Byte3 = 0
    else:
        length = 2
        Byte1 = 0
        Byte2 = 0
        Byte3 = 0
else:
    length = 1
    Byte0 = 0
    Byte1 = 0
    Byte2 = 0
    Byte3 = 0