A single DeltaV controller can host both DeltaV SIS hardware and DeltaV Intrinsically Safe (I.S.) cards making it possible to use DeltaV I.S. cards in a DeltaV Safety Instrumented System. One-wide carriers and extender cable, with the right one-wide carrier terminated, are used to connect DeltaV SIS to a second 8-wide carrier installed with DeltaV I.S. cards. A LocalBus Isolator and I.S. Power Supply must be installed on the second carrier. The LocalBus Isolator separates DeltaV I.S. cards from standard I/O cards to protect the I.S. cards from damaging voltages.