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ThinkCore W311/321/341 Linux User’s Manual Programmer’s Guide
6-7
The makefile is shown below:
all:
arm-linux-gcc –o xxxx xxxx.c –lmoxalib
UART
The normal tty device node is located at
/dev/ttyM0 … ttyM3
.
The W311/321/341 support Linux standard termios control. The Moxa UART Device API allows
you to configure ttyM0 to ttyM3 as RS-232, RS-422, 4-wire RS-485, or 2-wire RS-485. The
W311/321/341 support RS-232, RS-422, 2-wire RS-485, and 4-wire RS485.
You must
include <moxadevice.h>.
#define RS232_MODE 0
#define RS485_2WIRE_MODE 1
#define RS422_MODE 2
#define RS485_4WIRE_MODE 3
1. Function: MOXA_SET_OP_MODE
int ioctl(fd, MOXA_SET_OP_MODE, &mode)
Description
Set the interface mode. Argument 3 mode will pass to the UART device driver and change it.
2. Function: MOXA_GET_OP_MODE
int ioctl(fd, MOXA_GET_OP_MODE, &mode)
Description
Get the interface mode. Argument 3 mode will return the interface mode.
There are two Moxa private ioctl commands for setting up special baudrates.
Function: MOXA_SET_SPECIAL_BAUD_RATE
Function: MOXA_GET_SPECIAL_BAUD_RATE
If you use this ioctl to set a special baudrate, the termios cflag will be B4000000, in which case the
B4000000 define will be different. If the baudrate you get from termios (or from calling tcgetattr())
is B4000000, you must call ioctl with MOXA_GET_SPECIAL_BAUD_RATE to get the actual
baudrate.
Example to set 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 to get the baudrate
#include <moxadevice.h>
#include <termios.h>
struct termios term;
int fd, speed;
fd = open(“/dev/ttyM0”, O_RDWR);
tcgetattr(fd, &term);