Need Help with adding 30 minutes to a field

You need convert the starting time string to a number using the "Time2Num" function. Then add 30 minutes converted to the same time unit as the value from the "Time2Num" function. And then convert that value to the formatted time string using the "Num2Time" function.

if (HasValue($))then
MyDateTimeField3.rawValue = Num2Time(Time2Num($.formattedValue, "HH:MM") + (30 * 60 * 1000), "HH:MM")
endif


In simpler format:

// default value if no entry or entry cleared
MyDateTimeField3.rawValue = null
// if we have a time entered
if (HasValue($))then
// get time in milliseconds
var nTime = Time2Num($.formattedValue, "HH:MM")
// add 30 minutes in milliseconds
nTime = nTime + (30 * 60 * 1000)
// convert milliseconds to HH:MM
MyDateTimeField3.rawValue = Num2Time(nTime, "HH:MM")
endif

I've tried that, but the resulting field always shows "5:30 PM" no matter what I add to it ... I tried deleting both fields and inserting new fields to see if I had formatted something wrong. Still always "17:30" or "5:30 PM"

Are the form fields within the same subform?

Try:

if (HasValue($))then
xfa.host.messageBox(Num2Time(Time2Num($.formattedValue, "HH:MM") + (30 * 60 * 1000), "HH:MM"))
MyDateTimeField3.rawValue = Num2Time(Time2Num($.formattedValue, "HH:MM") + (30 * 60 * 1000), "HH:MM")
endif

You also might want to clear the result field if there is no time entered.

I also have the result field as a plain text field.

Same problem ... if I remove the " + (30 * 60 * 1000)" part, I get a blank answer ...so my "Time2Num($.formattedValue, "HH:MM") " must not be working correctly ...

I have uploaded a copy of my PDF to acrobat.com ... https://acrobat.com/#d=xgZ6Jh2wlYVkaQyzBYDuMA ... maybe you can see what's wrong with it?

Look at the format for your source date field. It is not the exactly the same as the format string you are providing for the conversion.

From the LiveCycle Designer Scriptting Reference for the Time2Num funciton:

The function returns a value of 0 if any of the following conditions are true:
• The format of the given time does not match the format specified in the function.

• Either the locale or time format supplied in the function is invalid.

Insufficient information is provided to determine a unique time since the epoch (that is, any information regarding the time is missing or incomplete.