A communication gateway apparatus for a substation automation system, the gateway includes a VERSA Module Eurocard (VME) bus to provide a data communication path, a Peripheral Component Interconnect (PCI)-VME module connected to the VME bus for communication and having a PCI-VME bus bridge circuit to transfer data of the VME bus to a PCI bus or data of the PCI bus to the VME bus, and a plurality of input/output modules connected to the VME bus for communication.