# PLC Offline \>\< Online

**URL:** <https://discourse.nodered.org/t/plc-offline-online/26252>\
**Category:** General\
**Created:** [7 May 2020 16:05 UTC](https://discourse.nodered.org/t/plc-offline-online/26252 "2020-05-07T16:05:02Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![rromele](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/rromele/32/18431_2.png) [@rromele](https://discourse.nodered.org/u/rromele)\
**Post date:** [7 May 2020 16:05 UTC](https://discourse.nodered.org/t/plc-offline-online/26252/1 "2020-05-07T16:05:03Z")

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Hi,  
when the plc is offline the flow stops, instead I would like to write the number "-1" in the following nodes, how could I do this?

 ![plc-01](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/3/4/34ac83e8474ab65c340f9d0e8e593fb4cfd32260.jpeg)

Thanks very much for your help.

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**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [7 May 2020 16:41 UTC](https://discourse.nodered.org/t/plc-offline-online/26252/2 "2020-05-07T16:41:44Z")

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Use a status node to monitor the status of them nodes  
Its relatively straightforward.  
Give it a go & come back if you get stuck.

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**Author:** ![kuema](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/kuema/32/6542_2.png) [@kuema](https://discourse.nodered.org/u/kuema)\
**Post date:** [7 May 2020 17:23 UTC](https://discourse.nodered.org/t/plc-offline-online/26252/3 "2020-05-07T17:23:56Z")

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Alternatively - or complementary to that - you could use a `trigger` node configured as a watchdog timer. That could send you a `-1` if no message has been received for a specific amount of time.

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**Author:** ![rromele](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/rromele/32/18431_2.png) [@rromele](https://discourse.nodered.org/u/rromele)\
**Post date:** [7 May 2020 22:41 UTC](https://discourse.nodered.org/t/plc-offline-online/26252/4 "2020-05-07T22:41:09Z")

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@[Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl), @[kuema](https://discourse.nodered.org/u/kuema), thank you very much for your help, I have successfully used both solutions, the w.dog node completes the status node.

 ![plc-2](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/c/c/ccc9f7169cdf432fa11cdc39d7b05393bb5ffbf6.jpeg)

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**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [21 May 2020 22:41 UTC](https://discourse.nodered.org/t/plc-offline-online/26252/5 "2020-05-21T22:41:12Z")

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