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);