帮我写一个485串口测试代码

好的，我可以回答这个问题。以下是一个简单的485串口测试代码示例：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>

int main()
{
int fd;
struct termios options;

// 打开串口
fd = open("/dev/ttyS", O_RDWR | O_NOCTTY | O_NDELAY);
if (fd == -1)
{
perror("open");
exit(1);
}

// 配置串口
tcgetattr(fd, &options);
cfsetispeed(&options, B960);
cfsetospeed(&options, B960);
options.c_cflag |= CLOCAL | CREAD;
options.c_cflag &= ~CSIZE;
options.c_cflag |= CS8;
options.c_cflag &= ~PARENB;
options.c_cflag &= ~CSTOPB;
options.c_cflag &= ~CRTSCTS;
options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
options.c_iflag &= ~(IXON | IXOFF | IXANY);
options.c_oflag &= ~OPOST;
options.c_cc[VMIN] = 1;
options.c_cc[VTIME] = ;
tcsetattr(fd, TCSANOW, &options);

// 发送测试数据
char buf[] = "Hello, world!";
int len = strlen(buf);
write(fd, buf, len);

// 接收测试数据
char recv_buf[256];
int recv_len = read(fd, recv_buf, sizeof(recv_buf));
if (recv_len > )
{
printf("Received: %.*s\n", recv_len, recv_buf);
}

// 关闭串口
close(fd);

return ;
}