Hi Ben,
Terribly sorry for all the trouble. I think we need to test the Fedora-build to see what happens. I'm quite sure it works on the Debian-build (which I use myself), can't confirm though since I'm off for the Christmas holiday. I'll be back on Monday again. Hopefully Claes (who produces all the packages) can make some test with the Fedora version.
I'll test it on monday if there is no response until then.
If you like to try you can use Proview both as a Master and as a Slave. You configure the Slave with a Modbus_TCP_Server. This should make it possible to test between two Proview-systems. This will though probably fail too I guess.
-Robert