JYG

I have used Kepware for several years but now it's a No-go. Kepware used licensing and lose licence when PC abnormally shutdown I must paid again to get my licence. The price is excessive. The NX102 have a OPC-UA server inside, and the cost is lower than KepServer. OPC is not appropriate for real time data.  

That's why I commented but I don't know what he want to do.

Yes, because the SktUDPSend() need a ARRAY[0..1999] of BYTE. Using ToAryByte() transform the structure in bytes and computes the size in the structure. Using the default Offset type NJ for the structure is the same packing and the same endian of Visual Studio C#. In C you can cast the bytes buffer receive from socket in pointer to struct. Voilà!

With TCP you must care of socket status and close the socket if it's not _ESTABLISHED. Take care with SktTCPGetStatus() because the outputs are valid only when Done flag is TRUE and the socket is not closed. Use WireShark software to see what is the problem.

You can look at Omron Instructions manual or on line help under SktUDPCreate() function for a complete example on the server side and client side. You must choose to use UDP or TCP for your application. Usually the PLC is the server and wait request from client but you can also choose to send data to client as soon new data is available. Your decision. If you have specific questions I will answer you.

Last NX firmware version 1.50 does not used HTTP protocol, now using TLS! The port 80 does not respond. The web server seem to be gone.

From W506 CPU Unit Built-in EtherNet/IP™ Port:  

You can't use same subnet IP!

Make your own Login/Logout dialog box and use timer to auto-logout.

Do you have read this manual : W22I-E-01 PackML Support Library Implementation Guide? The library is "OmronLib_PackML30V1_0.slr".  

NJ/NX-series CPU Unit Software User’s Manual (W501) page 8-25. 16GB FAT32.

Not understand your setup. Explain more in details please.

You must choose the appropriate direction CW or CCW in Setup and Tuning, transfer settings to drive and reboot the drive. Next do homing!

NJ/NX-series CPU Unit Software User’s Manual (W501) explain details (page 6-44). It is used for data alignment. In CJ data is packed and NJ is like Microsoft C default structure alignment. In User alignment you specify your needs with byte offset and bit offset.

A little library can help you implement HTTP server on the controller : https://www.support-omron.fr/details/librairie.php?id=2021-02-24%20-%2016-51-09%20-%202086348523 Only 2 FB :  HTTP_GET and HTTP_POST You can implement a little web server using REST API.