I have a main clock in place

the overtime clock = main clock - set time

the problem occures when the clock value roles over and the clockvalue - set_time < 0
during that time the value of the OT clock is incorrect

eg set time = 10 sec , when main clock counts to 1min , the over time clock would show 0.50 instead of 0.51 etc, for the duration of main clock moving 1.00 - 1.10 , then it be fine


this approch seems to be correct but i am not sure if it needs to be nested

Code:
 if     Days => Set_Day    and Hours => Set_Hour  and _
        Minutes => Set_Min and Seconds => Set_Sec and _
        100th => Set_100th then OT_Enable = 1
  
  
     if OT_Enable = 1 THEN      
        OT_Days    =  Days    - Set_Day  
        OT_Hours   =  Hours   - Set_Hour
        OT_Minutes = Minutes - Set_Min 
        OT_Seconds =Seconds - Set_sec
        OT_100th   = 100TH   - Set_100th
     endif 
     
      
      if  Hours   - Set_Hour <0 then
          OT_Days    = Days - 1
          OT_Hours   = 24 - Set_Day  + Hours 
      endif
     
     if   Minutes - Set_Min  <0 then 
          OT_Hours   = OT_Hours - 1
          OT_Minutes = 60 - Set_Min + Minutes 
      endif
    
     if  Seconds - Set_Sec   <0 then 
         OT_Minutes =  OT_Minutes - 1 
         OT_Seconds =  60 - Set_Sec + Seconds
      endif  
   
     if 100TH - Set_100th   <0 then
         OT_Seconds = OT_Seconds - 1
         Ot_100TH   = 100 - Set_100th + 100TH 
      endif