# Why is my time difference off by a second?

**URL:** <https://forum.inductiveautomation.com/t/why-is-my-time-difference-off-by-a-second/85258>\
**Category:** Ignition\
**Tags:** ignition81\
**Created:** [February 5, 2024, 9:03pm UTC](https://forum.inductiveautomation.com/t/why-is-my-time-difference-off-by-a-second/85258 "2024-02-05T21:03:31Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![JB77](https://avatars.discourse-cdn.com/v4/letter/j/f19dbf/32.png) [@JB77](https://forum.inductiveautomation.com/u/JB77)\
**Post date:** [February 5, 2024, 9:03pm UTC](https://forum.inductiveautomation.com/t/why-is-my-time-difference-off-by-a-second/85258/1 "2024-02-05T21:03:31Z")

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I have script for when a alarm is cleared to calculate how long the alarm was on. But when I test it out, the difference is sometimes off by a second.

```auto
def alarmCleared(tag, tagPath, alarmName, alarmEvent, alarmPath, missedEvents):

   # Get alarm details
	alarm = system.tag.read(tagPath).value
	active = alarmEvent.activeData.timestamp
	clear = alarmEvent.clearedData.timestamp

    # Convert Timestamp objects to java.util.Date if needed
	active_date = system.date.fromMillis(active)
	clear_date = system.date.fromMillis(clear)

    # Extract values
	value1 = exempt_default(tagPath)
	value2 = alarmName
	value3 = system.date.format(active_date, "MM/dd/yyyy")
	value4 = system.date.format(active_date, "hh:mm:ss a")
	value5 = system.date.format(clear_date, "hh:mm:ss a")

	# Calculate duration using system.date functions
	duration_seconds = system.date.secondsBetween(active_date, clear_date)

    # Round the duration to the nearest second
	rounded = round(duration_seconds)

    # Convert rounded duration to hours, minutes, and seconds
	hours = int(rounded // 3600)
	minutes = int((rounded % 3600) // 60)
	seconds = int(rounded % 60)
	
    # Format duration as HH:mm:ss
	value6 = "{:02}:{:02}:{:02}".format(hours, minutes, seconds)

    # Insert into database
	query = "INSERT INTO Alarm (Machine, Name, Date, TimeOn, TimeOff, Duration) VALUES (?,?,?,?,?,?)"
	args = [value1, value2, value3, value4, value5, value6]
	system.db.runPrepUpdate(query, args)
	
def exempt_default(tag_path):
	# Check if [default] is present in tag_path and remove it
	return tag_path.replace("[default]", "") if "[default]" in tag_path else tag_path

```

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<div class="post-metadata">

**Author:** ![JordanCClark](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/jordancclark/32/83362_2.png) [@JordanCClark](https://forum.inductiveautomation.com/u/JordanCClark)\
**Post date:** [February 5, 2024, 9:40pm UTC](https://forum.inductiveautomation.com/t/why-is-my-time-difference-off-by-a-second/85258/2 "2024-02-05T21:40:17Z")

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I'ds say it's rounding depending on the milliseconds. It is, still part of the date.

What happens of you use something like

`duration_seconds = (clear - active) / 1000.0`

or, if you're just looking to truncate the milliseconds:

`duration_seconds = (clear - active) // 1000`

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<div class="post-metadata">

**Author:** ![JB77](https://avatars.discourse-cdn.com/v4/letter/j/f19dbf/32.png) [@JB77](https://forum.inductiveautomation.com/u/JB77)\
**Post date:** [February 5, 2024, 9:46pm UTC](https://forum.inductiveautomation.com/t/why-is-my-time-difference-off-by-a-second/85258/3 "2024-02-05T21:46:46Z")

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Thank you, the `duration_seconds = (clear - active) / 1000.0` fixed the issue.