//?this?is?a?test?about?485?full-duplex?communication
//?hardware?:?MAX488

#include?
#include?
#include?

#include???????//?open（）?close（）
#include??????//?read（）?write（）

#include?????//?set?baud?rate

#include?
#include?
#include?
#include?


#define?DEVICE_TTYS?“/dev/ttyS2“
#define?MY_BAUD_RATE?B9600

#define?DATAS_CONTENT	“HELLO“

#define?RECEIVE_BUF_WAIT_1S?1
#define?RECEIVE_BUF_WAIT_2S?2
#define?RECEIVE_BUF_WAIT_3S?3
#define?RECEIVE_BUF_WAIT_4S?4
#define?RECEIVE_BUF_WAIT_5S?5

//-------------------------------------?read?datas?from?ttyS?------------------------------------------------
//?succese?return?1
//?error???return?0
int?read_datas_ttyS（int?fd?char?*rcv_bufint?rcv_wait）
{
????????int?retval;
????????fd_set?rfds;
????????struct?timeval?tv;

????????int?retpos;

????????tv.tv_sec?=?rcv_wait;???
????????tv.tv_usec?=?0;

????????pos?=?0;?//?point?to?rceeive?buf

????????while?（1）
????????{
????????????????FD_ZERO（&rfds）;
????????????????FD_SET（fd?&rfds）;

????????????????retval?=?select（fd+1??&rfds?NULL?NULL?&tv）;

????????????????if?（retval?==?-1）
????????????????{
????????????????????????perror（“select（）“）;
????????????????????????break;
????????????????}
????????????????else?if?（retval）
????????????????{//?pan?duan?shi?fou?hai?you?shu?ju
????????????????????????ret?=?read（fd?rcv_buf+pos?2048）;
????????????????????????pos?+=?ret;
????????????????????????if?（rcv_buf[pos-2]?==?‘\r‘?&&?rcv_buf[pos-1]?==?‘\n‘）
????????????????????????{
????????????????????????????????FD_ZERO（&rfds）;
????????????????????????????????FD_SET（fd?&rfds）;

????????????????????????????????retval?=?select（fd+1??&rfds?NULL?NULL?&tv）;

????????????????????????????????if?（!retval）?break;//?no?datas?break
????????????????????????}
????????????????}
????????????????else
????????????????{
?????????????????//???????printf（“No?data\n“）;
????????????????????????break;
????????????????}
????????}

????????return?1;
}?//?end?read_datas_ttyS


//-------------------------------------?send?and?receive?datas?by?RS485?-------------------------------------
int?func_485_transfer（int?fd）
{	
	ssize_t?ret;
	char?rcv_buf[1024];
	int?i;
????????char?*send_buf?=?DATAS_CONTENT;

	bzero（rcv_bufsizeof（rcv_buf））;
	
	while（1）?{
		//?send?datas
		ret?=?write（fdsend_bufstrlen（send_buf））;
????????????????if?（ret?==?-1）?{
????????????????????????printf?（“write?device?%s?error\n“?DEVICE_TTYS）;
????????????????????????return?-1;
????????????????}
		//?read?datas
		if?（read_datas_ttyS（fdrcv_bufRECEIVE_BUF_WAIT_1S））?{
			printf?（“%s\n“rcv_buf）;
		}
		else?{
			printf?（“read?error\n“）;
		}
	}
	
	return?0;

}?//?end?func_485_receive


//-------------------------------------?init?seriel?port??---------------------------------------------------
void?init_ttyS（int?fd）
{
????????struct?termios?options;

????????bzero（&options?sizeof（options））;???????	//?clear?options

????????c

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----

?????文件???????3925??2005-09-12?02:47??RS485實例代碼\full_488_test.c

?????文件???????7534??2005-09-12?02:47??RS485實例代碼\full_488_test.o

?????目錄??????????0??2007-09-01?21:26??RS485實例代碼

-----------?---------??----------?-----??----

????????????????11459????????????????????3