Read/write data from S7 with netPI over Profinet

[student]

Hello,

I need some help with my project. I have to read/write data from an S7 1500 PLC with the netPI using Node-RED over Profinet. The "netPI-nodered-fieldbus" container is running, I implemented the netPI into my TIA-Project, did the physical and software connection and I have included the Profinet-Node into my flow. Everything works fine. 

Now I want to read and write data from my DB, But how can I do this? The PUT/GET option is activated and the hook on static addresses is deleted in the properties of my DB.
I tried it with the s7comm-Nodes but this seems to be wrong, there is no connection respectively there is a missing configuration. 
Maybe I have to use a JSON payload after the fieldbus-in Node? But I don't know how to read data from my DB in the TIA Project with it.

I put my Flow into the attachment. 

Thanks!

Marcel