diff --git a/daq.c b/daq.c
index 5fcd322..01e2d2a 100644
--- a/daq.c
+++ b/daq.c
@@ -129,38 +129,37 @@ int str2int(unsigned char *ptr){
 
 int DAQ(int t_hrs, int tm_s)
 {
+  FILE* dfp;                                    // create a file pointer
   const char colums[200] = "t(s)\tCO2 uf(ppm)\tCO2(ppm)\tCO uf(ppm)\t"\
                            "CO(ppm)\tO2(ppm)\tO2(%%)\tT C02(ºC*10)\t"\
                            "T 02(ºC)\tP C02(.mBar)\tP 02(mBar)\tRH(.)\n";
-  FILE* dfp;                                    // create a file pointer
   unsigned char co2_uf[10]="", co2_f[10]="",
               co_uf[10]="", co_f[10]="",
               o2_ppm[10]="", o2_xcent[10]="",
               co2_temp[10]="", o2_temp[10]="",
               co2_press[10]="", o2_press[10]="",
               co2_relH[10]="", DATA[100]="";    //measurements varirables
+  time_t curtime;                               //current time (date)
   clock_t start_t, end_t;                       //processing time measurements variables
-  time_t new_time, prev_time, t0;               //time control variables
+  time_t next_samp_time;                        //time control variables
 	double tm_ms = tm_s*1e6 - 0.20e6;             //tiempo de muestreo en milisegundos (-) margen
 	double dif = tm_ms;                           //diferencia de tiempo(time to sleep)
 
+  time(&curtime);                               //saving date in curtime
   //registro datos de inicio
   dfp = fopen(data_file_path, "w");             // open file for writing
-  time_t curtime;                               //current time (date)
-  time(&curtime);                               //saving date in curtime
   // send the value to the file
   fprintf(dfp, "Starting DAQ at %s\n", ctime(&curtime);
   fclose(dfp);                                  // close the file using the file pointer
   printf("%s", colums);                         //display variables colums
   //ciclo
-  t0 = time(NULL) + tm_s;                       //intitial time = current time + tiempo de muestreo
-  new_time = t0;                                //saving initial time in time control variable
-  for(int i = 0; i < (t_hrs*3600); i=i+tm_s){   //cycle from 0 to adquisition time (seconds), incrementing sampling period
+  next_samp_time = time(NULL) + tm_s;           //setting nex sampling time
+  for(int t = 0; t < (t_hrs*3600); t+=tm_s){    //cycle from 0 to adquisition time (seconds), incrementing sampling period
     //checking if there's time to sleep
     if (dif <= 0) printf("Ejecution time exceded.\n%s", colums);
     else usleep((int)dif);                      //inactivity time
     //waiting to start measurements
-    while(new_time != time(NULL));
+    while(next_samp_time != time(NULL));
 
     start_t = clock();                          //saving start time
       //transmiting commands to sensors
@@ -186,14 +185,14 @@ int DAQ(int t_hrs, int tm_s)
       //saving formated measurements in string DATA
       sprintf(DATA,
               "%d\t%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s",
-              (int)(new_time-t0), co2_uf, co2_f, co_uf, co_f, o2_ppm, o2_xcent,
+              t, co2_uf, co2_f, co_uf, co_f, o2_ppm, o2_xcent,
               co2_temp, o2_temp, co2_press, o2_press, co2_relH);
       printf("\r%s", DATA);                     //showing measurements on display
 
       dfp = fopen(data_file_path, "a");         // open file for writing
           fprintf(dfp, "%s\n", DATA);           // saving measurements string to data file
       fclose(dfp);                              // close the file using the file pointer
-      new_time += tm_s;                         //adding sampling period to new_time
+      next_samp_time += tm_s;                         //adding sampling period to next_samp_time
     end_t = clock();                            //saving end time
     //calculate time to sleep
     dif =  tm_ms - ((double)(end_t - start_t)*1e6 / CLOCKS_PER_SEC);