Question

系统细节：Debian Jessie，gcc 4：4.9.2-2

我尝试使用以下代码对连接在串行端口上的仪器（自定义硬件，115200波特）进行长期测试：

    while (1)
    {
        // Setup nonblocking IO (unused)
        FD_SET(open_fds.serial.fd,&rset);

        usleep(1000000);

        // Write to instrument
        printf("About to send this message:\n");
        print_struct(i % 2 ? msg_test_be : msg_test_le, 12, 4);
        printf("Transmitting message as %s endian. Attempt number: %d\n", i % 2 ? "big" : "little", i);
        txlen = write(open_fds.serial.fd, i % 2 ? msg_test_be : msg_test_le, NUM_BITS_PER_CMD/CHAR_BIT);//      
        printf("%d bytes transmitted\n", txlen);

        // Read from instrument
        printf("Attempting to read from instrument. If this doesn't work, the serial connection may not be set up properly.\n");
        printf("Press Ctrl+C to cancel.\n");
        recvlen = read(open_fds.serial.fd, output, NUM_BYTES_PER_RESPONSE);
        printf("%d bytes read.\n", recvlen);
        printf("Response as hex:\n");
        print_struct((unsigned char *)output, recvlen, 15);

        i++;
    }

以下是print_struct的代码：

void print_struct(unsigned char *p, size_t length, int bytes_per_line)
{
    int i = 0;
    int modulus = bytes_per_line > MIN_BYTES_PER_LINE ? bytes_per_line : MIN_BYTES_PER_LINE;
    //printf("modulus: %d\n", modulus);
    for(i = 0; i < length; i++)
    {
        // Every "modulus" lines (excluding 0) print a newline.
        if(i && !(i % modulus) && i + 1 <= length) 
        {
            printf("\n");
        }
        printf("%02x ", p[i]);
    }
    // Throw in an extra newline to avoid colliding with other messages.
    printf("\n");
    return;
}

这适用于约700次迭代，然后它挂起。我觉得我有一些设置缺失可能导致它挂起，我想确保在部署仪器时不会发生这种情况。以下是我的串口设置：

int initSerial(int fd_tty, speed_t baud_rate, int vmin, int vtime) 
{
struct termios options;
    if(tcgetattr(fd_tty, &options) != 0)
    {
        //fprintf(fptr_log, "Error %d from tcgetattr in %s (%s)\n", errno, strerror(errno), __func__); 
        syslog(LOG_ERR, "Error %d from tcgetattr in %s (%s)\n", errno, strerror(errno), __func__);
        return EXIT_FAILURE; 
    }
    // Set the baud rates to whatever is needed... (Max 115200)
    cfsetispeed(&options, baud_rate);
    cfsetospeed(&options, baud_rate);
    options.c_cflag     &=      ~PARENB;
    options.c_cflag     &=      ~CSTOPB;
    options.c_cflag     &=      ~CSIZE;
    options.c_cflag     |=      CS8;
    options.c_cflag      &=      ~CRTSCTS;
    options.c_cc[VMIN]  =       vmin;
    options.c_cc[VTIME] =       vtime;
    options.c_cflag     |=      CREAD | CLOCAL;
    cfmakeraw(&options);

    // TODO: Add these functionalities back in.
//  options.c_cc[VMIN]  = vmin;  // vmin input bytes are enough to return from read()
//  options.c_cc[VTIME]  = vtime; // Or wait 0.1*vtime s if nothing to read 
    // Set the new options for the port...
        tcflush(fd_tty, TCIFLUSH);
        if(tcsetattr(fd_tty, TCSANOW, &options) !=0) 
    {
        //fprintf(fptr_log, "Error %d from tcsetattr: %s\n", errno, strerror(errno)); 
        syslog(LOG_ERR, "Error %d from tcsetattr in %s (%s)\n", errno, strerror(errno), __func__);
        return EXIT_FAILURE;
    }
return EXIT_SUCCESS;
}

我过去曾遇到过错误的串口设置问题，但是不知道在任何一个设置上都指责。有什么想法吗？

串行读取在C中经过一定时间后停止工作

0 个答案: