Endianess

[John Arvanitis]

I want to change the endaieness from litle to big

There is selecton on file endianconv.c (line 240) but this variable does not change the output on the UDP packet

Is there any error on that? 

[Martin Melik-Merkumians]

I am not sure what you are trying, but regardless of endianess, the payload should stay the same, as ENIP defines endianess on its network packets

[stm-at-esd]

Hi,

Am Montag, 25. Mai 2020 10:32:38 UTC+2 schrieb John Arvanitis:

I want to change the endaieness from litle to big

There is selecton on file endianconv.c (line 240) but this variable does not change the output on the UDP packet

 

The endian detection and selection only serves the purpose to make the OpENer run on little and big endian machines

without change. OpENer needs to know the endianness of the machine it runs on to know how to encode some data.

Also as Martin already mentioned the EtherNet/IP protocol itself is inherently little endian and all the protocol data keeps its

endianness.

If you want to change the endianness of your IO data in the IO data assembly the easiest way it would be if you put the data

in the g_assembly_data* array the way you want it on the network. This is possible because the GetAttributeSingle() function

that is called internally to transmit the data from the g_assembly_data* array to the network uses itself EncodeData() which in

turn for a assembly would use a plain memcpy() if it is defined as array of bytes.

If you violate the EtherNet/IP spec would in part also be depending on your *.eds file where you declare the type(s) and size

of the content of your assembly object.

YMMV,

    Stefan

[Martin Melik-Merkumians]

Hi,

I recently removed EncodeData in favor of function pointer, but you can achieve the same effect by providing a custom function to the assembly data.