Thread: Communication using RS232 port

Originally Posted by matsp

Code:

delay(10);

Would you think that waiting 0.01 seconds every character you output could have some effect on the transfer time? At 38400, this is equivalent of waiting for 384 bit times - so 38 characters, making it 39 two out of five waits.

Also calling fputc on every character will be noticably less efficient than buffering up some amount (such as 256 to 1024 bytes) and storing that using fwrite().

--
Mats

yes, sir i was just wondering why its taking so much time and realized that delay is the reason..also sir, I have one question,

If transfer can be done so easily using these commands then why use bioscom or createfile etc. commands? I mean what is the main difference?(just curious)..

Thanks
Edesign

Ok..thanks....
I got it...Now I will try using fiber optic kit that I have at my college...I hope that also work..

Thanks..all

Hello all,

I made a complete program & now suddenly I am facing a strange problem...for text files it works perfectly but for other type files it transfers 1KB & then stops..what can be the reason..

Code:

#include <stdio.h>
#include <dos.h>
#include<string.h>
#include<stdlib.h>
#include<conio.h>
#include<limits.h>
#define PORT1 0x3f8
#define PATH_MAX 512
long int length;
char ch,cha;
char a,c;
int choice,i;
void main()
{
   void transmitfile(FILE *,long int);
   void receivefile(FILE *);
   long int sizeoffile(FILE *);

   char filename[PATH_MAX],filename2[PATH_MAX],buf;
   FILE *in,*out;
   clrscr();
   outportb(PORT1+3,0x80);
   outportb(PORT1,0x03);
   outportb(PORT1+3,0x03);
   printf("\nthis computer is going to act as a:");
   printf("\n 1.sender \n2.receiver\n\nEnter the choice:");
   scanf("%d",&choice);
   char x;
   switch(choice)
   {
	   case 1:
		  x=getchar();
		  printf("enter the filename to be created:");
		  fgets(filename,PATH_MAX,stdin);
		  in=fopen(filename,"rb");
		  length=sizeoffile(in);
		  if(length!=NULL)
			printf("\n\nsending.....\n\n");
		  else
			printf("\n\nFile does not exist\n\n");
		  transmitfile(in,length);
		  fclose(in);
		  printf("Reading from the port...");
		  printf("writing to file %s",filename2);
		  break;
	   case 2:
		 x=getchar();
		 printf("enter the filename to be created:");
		 fgets(filename2,PATH_MAX,stdin);
		 out=fopen(filename2,"wb");
		 printf("Reading from the port...");
		 printf("writing to file %s",filename2);
		 receivefile(out);
		 break;
	   default:
		 exit(1);
}
getch();
}
long sizeoffile(FILE *fp){
   long curpos, length;
   curpos = ftell(fp);
   fseek(fp, 0L, SEEK_END);
   length = ftell(fp);
   fseek(fp, curpos, SEEK_SET);
   return(length);
}
void transmitfile(FILE *in,long int len)
   {
      long int i=0;
      do{
      {
       ch=fgetc(in);
       do{
			a=inportb(0x3fd)&0x40;
		 }while(a!=0x40);
       outportb(PORT1,ch);
	 //printf("%c",ch);
	 i++;
  }while(i<len);
  }
  void receivefile(FILE *out)
  {

  do
  {
	do
	  {
	   c=inportb(PORT1+5)&0x01;
	  }while(c!=0x01);
    cha=inportb(PORT1);
    //printf("%c",buf);
    fputc(cha,out);
    //delay(10);
  if(kbhit())
   {
     ch=getch();
   }
  }while(ch!=27);
  }

I can't find out what can go wrong...I changed everything I can think of causing the problem...

Thanks
Edesign

Hello Sir,

yes..I should move it before switch..also..I will change the fgets to readline that you suggested me ...then I will check again...If I keep the printf statements uncommented it prints same garbage on both screens...I'll check once again...

Thanks,
Edesign

Sir there is also one more question - general

When i pass the file path as command line arguments and if the path is having space " ", then it is not able to open the file...that is c:\documents & settings\hi.txt..can't be opened..how to overcome this?

Edesign