A critical component for a HMI Frontend is “Data Source”, meaning where is data loaded and saver. HMI alone is worthless unless it is actually connected to something. This can be a remote Modbus device, a database, simple memory structure, file structures etc. BSA will provide the component, but the user must add the source behind this API in ordinary code. This means that if your GUI display the value of a memory variable you need to put this inside a data source so that the GUI is updated every time you change that variable. This also means that updating the GUI now becomes as easy as setting a variable.
Modbus (as an example) is just as easy – you bind a modbus variable to the HMI and as the HMI write you write to the device and as the device update a variable the GUI is updated automatically.
The only difference between the pure HMI version and the later versions is that PLD can use data sources and process data. For now that needs to be done in source code. But, this is still a close to no-code system once you deal with the protocols.