写一段基于linux c开发的modbus tcp从站库
时间: 2023-08-12 10:27:38 浏览: 87
以下是一个简单的基于Linux C开发的Modbus TCP从站库的示例代码,供您参考:
```
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <errno.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include "modbus.h"
#define SERVER_ADDRESS "127.0.0.1"
#define SERVER_PORT 502
#define MAX_CONNECTIONS 5
#define MAX_BUFFER_SIZE 256
int server_socket;
modbus_t *modbus_ctx;
static void signal_handler(int sig)
{
if (sig == SIGINT) {
printf("Received SIGINT, closing server socket and freeing modbus context...\n");
modbus_close(modbus_ctx);
modbus_free(modbus_ctx);
close(server_socket);
exit(0);
}
}
int main(int argc, char **argv)
{
modbus_mapping_t *modbus_mapping;
modbus_ctx = modbus_new_tcp(SERVER_ADDRESS, SERVER_PORT);
server_socket = modbus_tcp_listen(modbus_ctx, MAX_CONNECTIONS);
if (server_socket == -1) {
printf("Failed to create server socket: %s\n", modbus_strerror(errno));
exit(1);
}
printf("Modbus TCP slave listening on %s:%d...\n", SERVER_ADDRESS, SERVER_PORT);
modbus_mapping = modbus_mapping_new(MODBUS_MAX_READ_BITS, MODBUS_MAX_WRITE_BITS, MODBUS_MAX_READ_REGISTERS, MODBUS_MAX_WRITE_REGISTERS);
signal(SIGINT, signal_handler);
while (1) {
modbus_t *client_ctx;
int client_socket;
struct sockaddr_in client_addr;
socklen_t client_addrlen = sizeof(client_addr);
uint8_t request[MAX_BUFFER_SIZE];
client_socket = accept(server_socket, (struct sockaddr *)&client_addr, &client_addrlen);
if (client_socket == -1) {
printf("Failed to accept client connection: %s\n", modbus_strerror(errno));
continue;
}
printf("Accepted client connection from %s:%d\n", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));
client_ctx = modbus_new_tcp_pi(SERVER_ADDRESS, "0", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));
if (client_ctx == NULL) {
printf("Failed to create client context: %s\n", modbus_strerror(errno));
close(client_socket);
continue;
}
modbus_set_socket(client_ctx, client_socket);
modbus_set_slave(client_ctx, 1);
while (1) {
int rc = modbus_receive(client_ctx, request);
if (rc == -1) {
printf("Failed to receive Modbus request: %s\n", modbus_strerror(errno));
break;
}
modbus_reply(client_ctx, request, rc, modbus_mapping);
}
printf("Closing client connection from %s:%d\n", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));
modbus_close(client_ctx);
modbus_free(client_ctx);
close(client_socket);
}
modbus_mapping_free(modbus_mapping);
return 0;
}
```
这个示例代码基于libmodbus库实现,可以作为一个简单的基础框架进行修改和扩展。请注意,这只是一个简单的示例,实际的Modbus从站库需要根据具体的应用场景进行设计和实现。
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