With this app you have access to the database of your siemens plc operator panel. You can read and write tag values. My next step will be to make a user interface where you can put buttons on and indicators to controle your HMI-PLC.
If you have suggestions or problems you can find my contact details on my website.
Be careful when you use my app on working machines. Be sure you know what you are doing.
How it works.
Create a PLC-HMI give it a name and fill in the IP-adress of the HMI device. Create a tag give it the same name as in database of the HMI (case sensitive) select the PLC-HMI and now you can read and write data to the tag.