This fault indicates that the communication between the IBC system and the FE-7 is not functioning properly.  Check the Ethernet cable that connects the two devices.  Make sure the cable configuration is correct.  If the FE-7 is connected directly to the IBC system or it is connected to an unmanaged switch, the Ethernet cable should be a cross-over cable.  If the FE-7 is connected to a managed switch or a router, it should be a straight through cable. If the Ethernet cable appears to be ok, check also the large 25 pin cable between the MBI and the measuring bar.