If you want to use more than one PLC on an MPI network, you would have to do:

        dc2 =daveNewConnection(di, 2nd_MPI_address, 0, 0);
        res =daveConnectPLC(dc2);

If you want to use more than one PLC over TCP connections, you would have to setup a second daveOSserialType, daveInterface and daveConnection:

        fds2.rfd=openSocket(102, IPaddress_of_CP);
        di2 =daveNewInterface(fds2, "IF2", 0, daveProtoISO_TCP, 0);
        dc2 =daveNewConnection(di2, 0, 0, 2);
        res =daveConnectPLC(dc2);