Hampster, I have seen the same Q on the Tridium forum. I have a similar issue for a different application (using Jace2 with new Tenant Billing Service) which requires data passing.
I understand from SupportUK that the options are the Obix service or Bacnet. For me they recommended bacnet as this is the first real job of this type. I am just setting up a test rig now.
Basically I need to expose R2 data as a series of Bacnet points and then read from a backnet service in AX and create proxy points in the usual way. First time for me (having just completed the AX cert course).
I suspect the same Bacnet approach will work for you. I'll keep you posted.
"Once men turned their thinking over to machines in the hope that this would set them free. But that only permitted other men with machines to enslave them."
- The Reverend Mother Gaius Helen Mohiam