Multitech MultiConnect MTPCIE-BW, Developer'S Manual

Page: 77 / 88

USING LINUX WITH H5 DEVICES
MultiConnect
®
PCIe MTPCIE-H5/MTPCIE-BW Developer Guide 77
int fd; // file descriptor for the /dev/ttyACM0 entry
if((fd = open("/dev/ttyACM0", O_RDONLY) < 0)
{
/* Error Management Routine */
} else {
/* ttyACM0 Device Opened */
}
read()
The read() function reads nbyte bytes from the file associated with the open file descriptor, fildes , and copies them
in the buffer that is pointed to by buf .
Header File
unistd.h
Prototype:
ssize_t read(int fildes, void *buf, size_t nbyte)
Parameters:
fildes - file descriptor
buf - destination buffer pointer
nbyte - number of bytes that read() attempts to read
Returns :
The number of bytes actually read if the operation is completed successfully, otherwise it is -1.
Example
Read sizeof(read_buff) bytes from the file associated with fd and stores them
into read_buff .
char read_buff[BUFF_LEN];
if(read(fd, read_buff, sizeof(read_buff)) < 0)
{
/* Error Management Routine */
} else {
/* Value Read */
}
write()
The write() function writes nbyte bytes from the buffer that are pointed by buf to the file associated with the open
file descriptor. fildes .
Header File
unistd.h
Prototype:
ssize_t write(int fildes, const void *buf, size_t nbyte)