# Tag Bad quality , replace null value to zero

**URL:** <https://forum.inductiveautomation.com/t/tag-bad-quality-replace-null-value-to-zero/57033>\
**Category:** Ignition\
**Created:** [March 9, 2022, 8:47pm UTC](https://forum.inductiveautomation.com/t/tag-bad-quality-replace-null-value-to-zero/57033 "2022-03-09T20:47:51Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![rigoberto.reyes](https://avatars.discourse-cdn.com/v4/letter/r/65b543/32.png) [@rigoberto.reyes](https://forum.inductiveautomation.com/u/rigoberto.reyes)\
**Post date:** [March 9, 2022, 8:47pm UTC](https://forum.inductiveautomation.com/t/tag-bad-quality-replace-null-value-to-zero/57033/1 "2022-03-09T20:47:51Z")

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Hi there.

I have created a memory tag “tAirFlow” composed of the next formula (tags):

{[.]Machine/Process/CoolerAirFlow\_01}+{[.]Machine/Process/CoolerAirFlow\_02}+{[.]Machine/Process/CoolerAirFlow\_03}+{[.]Machine/Process/CoolerAirFlow\_04}+{[.]Machine/Process/CoolerAirFlow\_05}+{[.]Machine/Process/CoolerAirFlow\_06}+{[.]Machine/Process/CoolerAirFlow\_07}

When machine is disconnected of the network, tAirFlow = null. Is there a way to replace null value to zero automatically?. I need to use that tag for another arithmetic calculations.

Thanks in advance.

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**Author:** ![KathyApplebaum](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kathyapplebaum/32/7261_2.png) [@KathyApplebaum](https://forum.inductiveautomation.com/u/KathyApplebaum)\
**Post date:** [March 9, 2022, 8:53pm UTC](https://forum.inductiveautomation.com/t/tag-bad-quality-replace-null-value-to-zero/57033/2 "2022-03-09T20:53:05Z")

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Coalesce might be what you want: [docs](https://docs.inductiveautomation.com/display/DOC81/coalesce)

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**Author:** ![rigoberto.reyes](https://avatars.discourse-cdn.com/v4/letter/r/65b543/32.png) [@rigoberto.reyes](https://forum.inductiveautomation.com/u/rigoberto.reyes)\
**Post date:** [March 14, 2022, 10:16pm UTC](https://forum.inductiveautomation.com/t/tag-bad-quality-replace-null-value-to-zero/57033/3 "2022-03-14T22:16:31Z")

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Thanks Kathy for your support. It works 😀