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I currently have a program that resets the rain counter with this code snippit:

'IF IT IS THE BEGINNING OF THE DAY THEN WE RESET THE DAILY RAIN TOTAL TO 0
If IfTime(0,1440,Min) Then
    SDI12Recorder (WXT(),C5,0,"XZRU!",1.0,0) 'THIS RESETS THE PRECIPITATION COUNTER
    SDI12Recorder (WXT(),C5,0,"XZRI!",1.0,0) 'THIS RESETS THE PRECIPITATION INTENSITY
    RainToday = 0
EndIf

Currently, my timestamp is set to Easter Standard Time (UTC-5) year-round. I want to change this to use UTC, and add a column for the local time using 

UTCOffset = 5*3600-DaylightSavingUS(-1)
TmStamp_Local = Public.TimeStamp(1,1) - UTCOffset

Thanks to "notcabbage" for his answer  in posting 

UTC and Local Data tables simultaneously - Campbell Scientific User Forums

I'm thinking that if I do this, IfTime(0, 1440, Min) will then actually be midnight UTC? 

Could I just change my code to

'5 hours early to account for UTC offset

If IfTime(-300, 1440,Min) Then  
    SDI12Recorder (WXT(),C5,0,"XZRU!",1.0,0) 'THIS RESETS THE PRECIPITATION COUNTER
    SDI12Recorder (WXT(),C5,0,"XZRI!",1.0,0) 'THIS RESETS THE PRECIPITATION INTENSITY
    RainToday = 0
EndIf

or maybe do this in Hours? (I inherited the current code)

If IfTime(-5, 24, hr) Then  
    SDI12Recorder (WXT(),C5,0,"XZRU!",1.0,0) 'THIS RESETS THE PRECIPITATION COUNTER
    SDI12Recorder (WXT(),C5,0,"XZRI!",1.0,0) 'THIS RESETS THE PRECIPITATION INTENSITY
    RainToday = 0
EndIf

Thanks in advance for any help.

I thought about this after I posted, but I still need to adjust for daylight saving time.

If IfTime(-300, 1440,Min) 

should probably be 

If IfTime(-UTCOffset/60, 1440,Min)

and 

If IfTime(-5, 24,hr) 

 should be

If IfTime(-UTCOffset/3600, 24,hr) 

 This will get you closer. DaylightSavingUS() only returns a value when the time change happens.

PreserveVariables
Public UTCOffset As Long = 5*3600

'Main Program
BeginProg
  Scan (1,Sec,0,0)
    'DaylightSavingUS only returns a value on the first scan at the new time
    'Use 0 in DaylightSavingUS to not adjust the clock
    UTCOffset += DaylightSavingUS(0)
  NextScan
EndProg

I am not completely certain this will work. The help for the instruction says the instruction returns 3600 when the time change happens. I am hoping it returns -3600 when time changes back. Otherwise, the offset would count up twice a year. 

Thanks JDavis. It turns out that 

UTCOffset = 5*3600-DaylightSavingUS(-1)
TmStamp_Local = Public.TimeStamp(1,1) - UTCOffset

 Does give me a value of 14400 (4 hours) now.(We'll see what happens next week.) However doing this

    UTCOffset_hrs = UTCOffset/3600
    If IfTime(-UTCOffset_hrs,24,Hr) Then
      SDI12Recorder (WXT(),C5,0,"XZRU!",1.0,0)    'THIS RESETS THE PRECIPITATION COUNTER
      SDI12Recorder (WXT(),C5,0,"XZRI!",1.0,0)    'THIS RESETS THE PRECIPITATION INTENSITY   
      RainToday = 0
    EndIf

did NOT work. Maybe it was because I was trying to use a negative value for TintoInt? Anyway, I changed the If clause to be

    If IfTime(24-UTCOffset_hrs,24,Hr) Then

 thinking that this will be true 4 hours before midnight UTC (8PM local EDT), since my datalogger is set to UTC time. Before I left work yesterday, I noticed that my rain count did get reset, but at 20:00 UTC, 16:00 local time. So I guess the clock for IfTime() is actually local time and not UTC after all, and the correct offset is 0. 

We had some light rain this morning. I haven't checked yet if the sensor picked it up yet (it was pretty light), so I suppose I'll know tomorrow morning if

    If IfTime(0,24,Hr) Then

 works as intended.

This post is under review.