# First out block

**URL:** <https://forum.inductiveautomation.com/t/first-out-block/75575>\
**Category:** General Discussion\
**Created:** [June 27, 2023, 12:28pm UTC](https://forum.inductiveautomation.com/t/first-out-block/75575 "2023-06-27T12:28:38Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Gourav\_Kumar](https://avatars.discourse-cdn.com/v4/letter/g/c68b51/32.png) [@Gourav\_Kumar](https://forum.inductiveautomation.com/u/Gourav_Kumar)\
**Post date:** [June 27, 2023, 12:28pm UTC](https://forum.inductiveautomation.com/t/first-out-block/75575/1 "2023-06-27T12:28:38Z")

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Dear team,

We have an requirement of first out block , which can tell which event call for DO activation.

Do anyone has prepared such block .

If yes, please share

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**Author:** ![Transistor](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/transistor/32/3380_2.png) [@Transistor](https://forum.inductiveautomation.com/u/Transistor)\
**Post date:** [June 27, 2023, 12:30pm UTC](https://forum.inductiveautomation.com/t/first-out-block/75575/2 "2023-06-27T12:30:40Z")

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What is a "DO activation"?

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**Author:** ![Gourav\_Kumar](https://avatars.discourse-cdn.com/v4/letter/g/c68b51/32.png) [@Gourav\_Kumar](https://forum.inductiveautomation.com/u/Gourav_Kumar)\
**Post date:** [June 27, 2023, 2:28pm UTC](https://forum.inductiveautomation.com/t/first-out-block/75575/3 "2023-06-27T14:28:08Z")

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We have written a logic in hardware, which activate my relay i.e DO block.Now my customer demanks to know, which input signal Activa which call for Module DO activation

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**Author:** ![woodsb02](https://avatars.discourse-cdn.com/v4/letter/w/6a8cbe/32.png) [@woodsb02](https://forum.inductiveautomation.com/u/woodsb02)\
**Post date:** [June 30, 2023, 11:18am UTC](https://forum.inductiveautomation.com/t/first-out-block/75575/4 "2023-06-30T11:18:18Z")

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I've typically seen the first out logic added to the PLC code.  
Then in the SCADA package you would simply read the first out boolean from the PLC, and add an alarm to it.