SCADA connection to KNX bus using LM5 and VPN

[Higgel]

Hi.

We have a sentral SCADA system running on Niagara, thats connected to many buildings and in one of them we want to connect to it to the KNX bus.
The SCADA system is connected to the buildings using IXON VPN routers. 
We've tried to connect the SCADA system to both KNX-IP routers and a LM5 to get access to the KNX bus but without any success.
We where able to connect to the IP-routers and LM5 using ETS with NAT enabled, it didn't work without NAT.
I was wondering if its possible to connect the SCADA system to the knx bus like I've described?

This is how the topology should look like:
   

[Daniel]

Yes NAT would be needed in such config and if Niagara is not supporting it then nothing we can do. Why don't you use BACnet? As farI know Niagara supports it. BBMD server will be needed for this.