Linux c使用485通讯，ioctl的配置

//原文链接：https://www.kernel.org/doc/Documentation/serial/serial-rs485.txt
#include <linux/serial.h>

/* Include definition for RS485 ioctls: TIOCGRS485 and TIOCSRS485 */
#include <sys/ioctl.h>

/* Open your specific device (e.g., /dev/mydevice): */
int fd = open ("/dev/mydevice", O_RDWR);
if (fd < 0) {
/* Error handling. See errno. */
}

struct serial_rs485 rs485conf;

/* Enable RS485 mode: */
rs485conf.flags |= SER_RS485_ENABLED;

/* Set logical level for RTS pin equal to 1 when sending: */
rs485conf.flags |= SER_RS485_RTS_ON_SEND;
/* or, set logical level for RTS pin equal to 0 when sending: */
rs485conf.flags &= ~(SER_RS485_RTS_ON_SEND);

/* Set logical level for RTS pin equal to 1 after sending: */
rs485conf.flags |= SER_RS485_RTS_AFTER_SEND;
/* or, set logical level for RTS pin equal to 0 after sending: */
rs485conf.flags &= ~(SER_RS485_RTS_AFTER_SEND);

/* Set rts delay before send, if needed: */
rs485conf.delay_rts_before_send = ...;

/* Set rts delay after send, if needed: */
rs485conf.delay_rts_after_send = ...;

/* Set this flag if you want to receive data even whilst sending data */
rs485conf.flags |= SER_RS485_RX_DURING_TX;

if (ioctl (fd, TIOCSRS485, &rs485conf) < 0) {
/* Error handling. See errno. */
}

/* Use read() and write() syscalls here... */

/* Close the device when finished: */
if (close (fd) < 0) {
/* Error handling. See errno. */
}