int main(void)
{
int socket;
modbus_param_t mb_param;
modbus_mapping_t mb_mapping;
int ret;
modbus_init_tcp(&mb_param, "127.0.0.1", 1502);
ret = modbus_mapping_new(&mb_mapping, MAX_STATUS, 0, MAX_REGISTERS, 0);
if (ret == FALSE) {
printf("Memory allocation failed\n");
exit(1);
}
socket = modbus_init_listen_tcp(&mb_param);
while (1) {
uint8_t query[MAX_MESSAGE_LENGTH];
int query_size;
ret = modbus_listen(&mb_param, query, &query_size);
if (ret == 0) {
modbus_manage_query(&mb_param, query, query_size, &mb_mapping);
} else if (ret == CONNECTION_CLOSED) {
/* Connection closed by the client, end of server */
break;
} else {
printf("Error in modbus_listen (%d)\n", ret);
}
}
close(socket);
modbus_mapping_free(&mb_mapping);
modbus_close(&mb_param);
return 0;
}
int main(void)
{
int master_socket;
int rc;
fd_set refset;
fd_set rdset;
/* Maximum file descriptor number */
int fdmax;
ctx = modbus_new_tcp("127.0.0.1", 1502);
mb_mapping = modbus_mapping_new(MODBUS_MAX_READ_BITS, 0,
MODBUS_MAX_READ_REGISTERS, 0);
if (mb_mapping == NULL) {
fprintf(stderr, "Failed to allocate the mapping: %s\n",
modbus_strerror(errno));
modbus_free(ctx);
return -1;
}
server_socket = modbus_listen(ctx, NB_CONNECTION);
signal(SIGINT, close_sigint);
/* Clear the reference set of socket */
FD_ZERO(&refset);
/* Add the server socket */
FD_SET(server_socket, &refset);
/* Keep track of the max file descriptor */
fdmax = server_socket;
for (;;) {
rdset = refset;
if (select(fdmax+1, &rdset, NULL, NULL, NULL) == -1) {
perror("Server select() failure.");
close_sigint(1);
}
/* Run through the existing connections looking for data to be
* read */
for (master_socket = 0; master_socket <= fdmax; master_socket++) {
if (FD_ISSET(master_socket, &rdset)) {
if (master_socket == server_socket) {
/* A client is asking a new connection */
socklen_t addrlen;
struct sockaddr_in clientaddr;
int newfd;
/* Handle new connections */
addrlen = sizeof(clientaddr);
memset(&clientaddr, 0, sizeof(clientaddr));
newfd = accept(server_socket, (struct sockaddr *)&clientaddr, &addrlen);
if (newfd == -1) {
perror("Server accept() error");
} else {
FD_SET(newfd, &refset);
if (newfd > fdmax) {
/* Keep track of the maximum */
fdmax = newfd;
}
printf("New connection from %s:%d on socket %d\n",
inet_ntoa(clientaddr.sin_addr), clientaddr.sin_port, newfd);
}
} else {
/* An already connected master has sent a new query */
uint8_t query[MODBUS_TCP_MAX_ADU_LENGTH];
rc = modbus_receive(ctx, master_socket, query);
if (rc != -1) {
modbus_reply(ctx, query, rc, mb_mapping);
} else {
/* Connection closed by the client, end of server */
printf("Connection closed on socket %d\n", master_socket);
close(master_socket);
/* Remove from reference set */
FD_CLR(master_socket, &refset);
if (master_socket == fdmax) {
fdmax--;
}
}
}
}
}
}
return 0;
}
