楼主：以前用过你想要的方法，看看这个东东，也许对你有些帮助！
int GetpointFromPlc()
{
FILE *fp1,*fp2;
char *infile="D:\\Data_WinCC\\TagList\\TagList_Setpoint.txt";
char *outfile="D:\\Data_WinCC\\ValueList\\Value_Setpoint.txt",line[30];
DWORD dwState=0;
if (dwState==0)
{
//WinCC & PLC Connection OK
if ((fp1=fopen(infile,"r"))==NULL) return 0;
if ((fp2=fopen(outfile,"w"))==NULL)
{
fclose(fp1);
return 0;
}
while (fscanf(fp1,"%s",line) != EOF)
fprintf(fp2,"%12.3f\n",GetTagFloat(line));
fclose(fp1);
fclose(fp2);
}
return 1;
}
////////////////////////////////////////////////////////////////////////////////
楼主你理解了上面的东东，就可以自己写SetpointToPLC() 了，我就不重复了！