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UC-7420/7410 User’s Manual Programmer’s Guide
5-9
UART
The normal tty device node is located at
/dev/ttyM0 … ttyM7
, and the modem tty device node is
located at
/dev/cum0 … cum7
.
UC-7420/7410 supports Linux standard termios control. The Moxa UART Device API allows you
to configure ttyM0 to ttyM7 as RS-232, RS-422, 4-wire RS-485, or 2-wire RS-485. UC-7420/7410
supports 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 baud rates.
Function: MOXA_SET_SPECIAL_BAUD_RATE
Function: MOXA_GET_SPECIAL_BAUD_RATE
If you use this ioctl to set a special baud rate, the termios cflag will be B4000000, in which case
the B4000000 define will be different. If the baud rate you get from termios (or from calling
tcgetattr()) is B4000000, you must call ioctl with MOXA_GET_SPECIAL_BAUD_RATE to get
the actual baud rate.
Example to set the baud rate
#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 baud rate
#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);
}