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/* DESC: This script can be used to access to the digital I/Os via Modbus TCP * Copyright (C) 2015 NetModule AG, Switzerland * supports Read Coil Status (FC01), Read Input Status (FC02) and Force Single Coil (FC05) * Mapping: * Coil(digital I/O): 1=out1, 2=out2 * Input(digital In): 1=in1, 2=in2 */ TCP_PORT = 1502; // sdk port must be higher than 1024 SLAVEID = 7; if ((fd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0) { printf("Unable to open socket\n"); exit(1); } if (bind(fd, TCP_PORT, "") < 0) { printf("Unable to bind port %d\n", TCP_PORT); exit(2); } if (listen(fd, 1) < 0) { printf("Unable to listen\n"); exit(3); } cfd = -1; for(;;) { if (cfd == -1) { if ((cfd = accept(fd)) < 0) { printf("accept failed\n"); continue; } if (nb_modbus_register(cfd, MODBUS_TYPE_TCP) < 0) { printf("Unable to register client (%s)\n", nb_modbus_last_error()); close(cfd); cfd = -1; continue; } } if ((r = nb_modbus_receive(cfd)) == NULL) { printf("Unable to receive request (%s)\n", nb_modbus_last_error()); nb_modbus_unregister(cfd); close(cfd); cfd = -1; continue; } if (r[6] == SLAVEID) { switch (r[7]) { // command case 1: // read coil status case 2: // read input status break; // no write, only reply needed case 5: // write to a single coil addr = r[8]<<8 + r[9]; data = r[10]<<8 + r[11]; switch (addr) { //switch on address case 0: if (data == 0) nb_dio_set("out1", 0); else nb_dio_set("out1", 1); break; case 1: if (data == 0) nb_dio_set("out2", 0); else nb_dio_set("out2", 1); break; } break; } // reply for all commands resp = mkstruct( "bits", mkarray(nb_dio_get("in1"), nb_dio_get("in2")), "ibits", mkarray(nb_dio_get("out1"), nb_dio_get("out2")), "regs", mkarray(), "iregs", mkarray() ); if (nb_modbus_reply(cfd, r, resp) < 0) { printf("Unable to reply%s)\n", nb_modbus_last_error()); nb_modbus_unregister(cfd); close(cfd); cfd = -1; continue; } } } /* not reached */