Acceleport Xem PCI

Can anyone tell me what the maximum distance is between the Acceleport Xem PCI card and the C/CON concentrator ?
Is it possible to connect the concentrator using RS-485 ?

C/CON Concentrators will not work with the AccelePort XEM adapter. Only Ports/em modules can be attached to this adapter.

The EBI cable used to connect the modules is proprietary and has a maximum length of 10 feet from the host adapter to the last Ports/em module. This is due to the modules obtaining the power from the host systems bus.