What language do you code in? I typically stick to C/C++, but there are examples in all languages. More details would help, but if you are interested in reliable communications, then you probably want a TCP programming tutorial in your preferred language. If you have local networks and need low latency but can tolerate some dropped data, then you probably want a UDP tutorial. If there is a standard interface for network data on the PLC, then you might need to combine that with TCP or UDP.
In some cases the program “netcat” (the command “nc”, see “man nc”) can be used over the network just like “cat” can be used with an ordinary text file on a local computer (e.g., “cat /proc/cmdline” to see the boot options…this is just a text file, and “nc” can do this between two computers instead of to the local console…redirects can use that as a program’s data).
Many more details on the nature of the data would be required before being able to make specific suggestions. Details like whether it is binary data might help, if there is a continuous stream of small amounts of data, if it is a lot of data (e.g., a 4k 60Hz monitor’s data for images would be a lot, reading a temperature probe once per second would be tiny; copying files in a batch mode would change how you do this versus continuously streamed data). Maybe information on how critical latency is would help.