# Inter-PLC COmmunication

**URL:** <https://forum.inductiveautomation.com/t/inter-plc-communication/11883>\
**Category:** General Discussion\
**Created:** [June 30, 2016, 8:05am UTC](https://forum.inductiveautomation.com/t/inter-plc-communication/11883 "2016-06-30T08:05:58Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Frandee](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/frandee/32/4699_2.png) [@Frandee](https://forum.inductiveautomation.com/u/Frandee)\
**Post date:** [June 30, 2016, 8:05am UTC](https://forum.inductiveautomation.com/t/inter-plc-communication/11883/1 "2016-06-30T08:05:58Z")

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Can we use Ignition as Inter-PLC Communication between several PLCs where we don’t have to use messaging? Can we send/read data from one PLC thru gateway then pass it to the other PLC?

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**Author:** ![Chris\_Taylor](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/chris_taylor/32/3315_2.png) [@Chris\_Taylor](https://forum.inductiveautomation.com/u/Chris_Taylor)\
**Post date:** [June 30, 2016, 8:39am UTC](https://forum.inductiveautomation.com/t/inter-plc-communication/11883/2 "2016-06-30T08:39:22Z")

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Yes, use transaction groups  
but only for non critical data.

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**Author:** ![Frandee](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/frandee/32/4699_2.png) [@Frandee](https://forum.inductiveautomation.com/u/Frandee)\
**Post date:** [July 1, 2016, 5:45am UTC](https://forum.inductiveautomation.com/t/inter-plc-communication/11883/3 "2016-07-01T05:45:21Z")

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thanks for the reply bro!!!

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**Author:** ![Curlyandshemp](https://avatars.discourse-cdn.com/v4/letter/c/bcef8e/32.png) [@Curlyandshemp](https://forum.inductiveautomation.com/u/Curlyandshemp)\
**Post date:** [July 1, 2016, 1:46pm UTC](https://forum.inductiveautomation.com/t/inter-plc-communication/11883/4 "2016-07-01T13:46:41Z")

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[quote=“Chris Taylor”]Yes, use transaction groups  
but only for non critical data.[/quote]

+1 on that.  
Good design practice is to never have a more reliable device rely on a less reliable device.

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**Author:** ![abishur](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/abishur/32/9096_2.png) [@abishur](https://forum.inductiveautomation.com/u/abishur)\
**Post date:** [July 1, 2016, 2:47pm UTC](https://forum.inductiveautomation.com/t/inter-plc-communication/11883/5 "2016-07-01T14:47:40Z")

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> [@Curlyandshemp](#):
>
> Good design practice is to never have a more reliable device rely on a less reliable device.

+1

I can't tell you how many times I've been tasked with upgrading a system to a different HMI package only to find out that it had extremely critical data being computed in the HMI and then relayed to a different PLC. It's a nightmare full of non-euclidean logic and dead-ends in dark alleys where bad things happen. 😮

For PLC-to-PLC communication where the two devices cannot communicate to each other natively, you might want to check out something like the Red Lion DSPLE it's less than $600 last I checked and a more robust solution than HMI based communications