There is also MQTT integrating bus-hardware- you basically plug in as bus-hardware replacement which allows to send data directly from the bus to the broker. The PLC never know what hit it.

https://www.ifm.com/de/de/product/AL1332

Pretty wild times.

PS: You can web GET/POST set and get ios with these. Robot experience that tragic irony POST {NOOO} and he just dropped it like its hot.

In some cases yes, controllers are adding in MQTT support directly or SparkplugB.

It works in simple cases, but the lack of transactions & ability to control what and how often you're reading from the client side, can create challenges.