I'll try to make some things clear. In an EtherNet/IP setup there is typically a master station that talks to and controls multiple slave stations. I use this "old" language only to make the control relationship clear. In the EtherNet/IP community it is talked about the master to be the "EtherNet/IP scanner" device and the slave is the "EtherNet/IP adapter" device. That was Martin talking about that the OpENer is an "EtherNet/IP adapter" device protocol stack.
This differs in great length from an "EtherNet/IP scanner" device. This is I assume what you mean with "primary station". I don't know how far parts of the code of OpENer could be used to implement parts of a scanner device. But I think it is far from being usable as scanner protocol stack.
If you are interested in a "EtherNet/IP scanner" protocol stack you may buy some here:
Best regards,
Stefan