Hi René,
currently SIMATIC AX capabilities to expose variables to external/internal are limited. There are no integrated/internal connection mechanisms as of now, but you can declare variables to be exposed and use external mechanisms.
For any external client who wants to access the variables from the PLC-1500 runtime (AX loaded), we recommend creating an OPC UA server interface.
{OpcUa=ReadWrite}
{S7.extern=ReadWrite}
VAR_GLOBAL
var1 : BOOL;
var2 : typeA;
END_VAR
apax add @ax/opcua-server-config
On a side note:
Any variables exposed via the {S7.extern=...} pragma this way will be accessible by any client tools that can establish a non-integrated S7 connection (including browsing). For example: NX MCD.
If you know the FQN of the variables on the runtime, you may be able to make other mechanisms work as well. This is at your own risk and may be subject to change, so be aware.
If you have any further questions or need additional support, feel free to reach out to me!
Greetings
Fabian
You could also have a look at the "coupling DBs" feature
https://console.simatic-ax.siemens.io/docs/tia2st/import-db
This allows you to generate a SIMATIC AX library to include in your project which provides access to DBs defined in TIA Portal.
Access to HMI data blocks is one of the listed use cases.