Hi Simon,
what exactly do you mean with "web application running on the S7-1500"? I assume you are speaking of an external application using the WebAPI?! https://github.com/siemens/simatic-s7-webserver-api
If so, yes - that is possible. Altough you don't explicitly define DBs in AX, you can access variables of you PLC program from external applications. For security reasons, no variable is accessible by default, adhering to the need-to-know principle. Therefore, you must explicitly enable access to the variables of your application!
This is achieved by adding pragmas to your ST code. For example:
VAR_GLOBAL
{S7.extern=ReadWrite}
MotorOn : BOOL; // variable can be read and written
{S7.extern=ReadOnly}
MotorState: INT; // variable can only be read
MotorFlags: UINT; // variable is not accessible by an external system (default: hidden)
END_VAR
The webserver can be enabled in the hardware configuration, either in the TIA Portal project used to set up the PLC or by using the AX hardware engineering.
If you already have access to the SIMATIC AX documentation, you can find more information on this topic here: https://console.simatic-ax.siemens.io/docs/sld/extern-accessibility
Best regards,
Johannes
Yes, there are more ways
1. REST API Communication (via Mendix and S7-1500 Web Server)
2. WebSockets