# S7-node/DataBase

**URL:** <https://discourse.nodered.org/t/s7-node-database/50494>\
**Category:** General\
**Created:** [1 September 2021 09:52 UTC](https://discourse.nodered.org/t/s7-node-database/50494 "2021-09-01T09:52:10Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![grandautism](https://avatars.discourse-cdn.com/v4/letter/g/b5ac83/32.png) [@grandautism](https://discourse.nodered.org/u/grandautism)\
**Post date:** [1 September 2021 09:52 UTC](https://discourse.nodered.org/t/s7-node-database/50494/1 "2021-09-01T09:52:10Z")

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Hello,  
I have a question, I read data of the sensors from API by S7 node, and I send this data to a database that I created. What I want to do is that if I add a sensor, I want it to be added without modifying my node or add variable. Is that possible with node S7, or if you have a proposition I would be glad.  
Thank you

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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:** [1 September 2021 11:20 UTC](https://discourse.nodered.org/t/s7-node-database/50494/2 "2021-09-01T11:20:58Z")

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> [@grandautism](#):
>
> I want it to be added without modifying my node or add variable. Is that possible with node S7

Yes of course this is possible I actually do this myself. In the PLC is ladder that buffers sensor data in a FIFO and presents it for collection in one fixed/known memory area that node-red polls. When future sensors are added to the PLC, we simply add a line of ladder to push its value into the the FIFO buffer and the existing framework collects this data.

This is a slightly more descriptive post here...

> [@Scalability Node-Red](https://discourse.nodered.org/t/scalability-node-red/18294/13):
>
> Actually, it is 123 (but I seem to remember the node-red implimentation is fixed at 100 for some reason) [ref](https://en.wikipedia.org/wiki/Modbus#:~:text=Because%20the%20number%20of%20bytes,can%20be%20read%20at%20once.) This limit is hidden by driver implementation. What is happening under the hood is - multiple requests/polls are occurring. Even on your SCADA. PS, 2000 data per second is (probably) easily achievable in node-red too. If you are unaware of this, you can (AND WILL) eventually hit issues with inconsistent data (i.e. the 1st item of 10000 would probably have been read 100 polls before t…

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**Author:** ![grandautism](https://avatars.discourse-cdn.com/v4/letter/g/b5ac83/32.png) [@grandautism](https://discourse.nodered.org/u/grandautism)\
**Post date:** [1 September 2021 12:31 UTC](https://discourse.nodered.org/t/s7-node-database/50494/3 "2021-09-01T12:31:58Z")

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I don't know if I get it  
With the S7 node we should declare every single variable so that we can read it. How we can get this variables automatically via PLC  
Do you have an example you o fthis application ?

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/7/4/746430e8b70887e30d0e3f6277ea145142013cda.png)

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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:** [31 October 2021 12:32 UTC](https://discourse.nodered.org/t/s7-node-database/50494/4 "2021-10-31T12:32:47Z")

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