Moxa UC-8416-T-LX [66/90] Baudrate inaccuracy

UC-8410/8416/8418/8430 Programmer's Guide

5-14

2 RS-422

3 RS-485 4-wire

The following example sets /dev/ttyM0 to RS-422 mode

Example for setting the baudrate

#include <moxadevice.h>

#include <termios.h>

struct termios term;

int fd, speed;

fd = open(“/dev/ttyM0”, O_RDWR);

tcgetattr(fd, &term);

term.c_cflag &= ~(CBAUD | CBAUDEX);

term.c_cflag |= B4000000;

tcsetattr(fd, TCSANOW, &term);

speed = 500000;

ioctl(fd, MOXA_SET_SPECIAL_BAUD_RATE, &speed);

Example for getting the baudrate

#include <moxadevice.h>

#include <termios.h>

struct termios term;

int fd, speed;

fd = open(“/dev/ttyM0”, O_RDWR);

tcgetattr(fd, &term);

if ( (term.c_cflag & (CBAUD|CBAUDEX)) != B4000000 )

{// follow the standard termios baud rate define} else

{ioctl(fd, MOXA_GET_SPECIAL_BAUD_RATE, &speed);}

Baudrate inaccuracy

Divisor = 921600/Target Baud Rate. (Only Integer part)

ENUM = 8 * (921600/Target - Divisor) ( Round up or down)

Inaccuracy = (Target Baud Rate – 921600/(Divisor + (ENUM/8))) / Target Baud Rate * 100%

E.g.,

To calculate 500000 bps

Divisor = 1, ENUM = 7,

Inaccuracy = 1.7%

NOTE: The Inaccuracy should less than 2% for the device to work reliably.

Special Note

1. If the target baudrate is not a special baudrate (e.g., 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800,

2400, 4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800, 921600), the termios cflag will be set

to the same flag.

root@Moxa:/# setinterface /dev/ttyM0 2

root@Moxa:~# setinterface /dev/ttyM0

Now setting is RS422 interface.

root@Moxa:~#