# Start and End data values

**URL:** <https://forum.inductiveautomation.com/t/start-and-end-data-values/42912>\
**Category:** Ignition\
**Tags:** ignition80, vision\
**Created:** [February 2, 2021, 8:22pm UTC](https://forum.inductiveautomation.com/t/start-and-end-data-values/42912 "2021-02-02T20:22:02Z")\
**Posts on this page:** 1\
**Page:** 3

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**Author:** ![justinedwards.jle](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/justinedwards.jle/32/37854_2.png) [@justinedwards.jle](https://forum.inductiveautomation.com/u/justinedwards.jle)\
**Post date:** [September 27, 2023, 1:22am UTC](https://forum.inductiveautomation.com/t/start-and-end-data-values/42912/41 "2023-09-27T01:22:55Z")

</div>

> [@robb](#):
>
> how do I set the initial state of the easychart to not include that time?

A simpler solution would be to check if any of the values are null before doing the calculation, and if null values are present, handle it in some way.

**Example:**

```auto
# Check if null values are present.
if startVol is not None and endVol is not None and adjVol is not None:

	#If all values are good, perform the calculation
	diffVol = startVol - endVol - adjVol
else:

	#If there are null values, handle it by zeroing the diffVol variable.
	diffVol = 0

```

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