emlxs_rpi_find
rpip = emlxs_rpi_find(port, rpi);
rpip = emlxs_rpi_find(port, rpi);
extern RPIobj_t *emlxs_rpi_find(emlxs_port_t *port, uint16_t rpi);
((_n)?((_n->rpip)?_n->rpip:emlxs_rpi_find(_p, _n->nlp_Rpi)):NULL)