楼主：神马也不说，就贴点代码吧！（仅供参考）
int SetpointToPLC()
{
FILE *fp1,*fp2;
float sv;
char *infile1="e;D:\\Data_WinCC\\TagList\\TagList_Setpoint.txt"e;;
char *infile2="e;D:\\Data_WinCC\\ValueList\\Value_Setpoint.txt"e;,line1[30],line2[30];
if ((fp1=fopen(infile1,"e;r"e;))==NULL) return 0;
if ((fp2=fopen(infile2,"e;r"e;))==NULL)
{
fclose(fp1);
return 0;
}
while (fscanf(fp1,"e;%s"e;,line1) != EOF)
{
if (fscanf(fp2,"e;%s"e;,line2) == EOF)
{
fclose(fp1);
fclose(fp2);
return 0;
}
sv=atof(line2);
SetTagFloat(line1,sv);
}
fclose(fp1);
fclose(fp2);
return 0;
}