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Read/write data from S7 with netPI over Profinet
#1
Hello,

I need some help with my project. I have to read/write data from an S7 1500 PLC with the netPI using Node-RED over Profinet. The "netPI-nodered-fieldbus" container is running, I implemented the netPI into my TIA-Project, did the physical and software connection and I have included the Profinet-Node into my flow. Everything works fine. 

Now I want to read and write data from my DB, But how can I do this? The PUT/GET option is activated and the hook on static addresses is deleted in the properties of my DB.
I tried it with the s7comm-Nodes but this seems to be wrong, there is no connection respectively there is a missing configuration. 
Maybe I have to use a JSON payload after the fieldbus-in Node? But I don't know how to read data from my DB in the TIA Project with it.

I put my Flow into the attachment. 

Thanks!

Marcel

 


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#2
Hello, your understanding is not correct.

If you want to read/write data sets from/to an S7 PLC like your Windows TIA portal software is doing it during programming session or diagnostics then you do NOT need fieldbus nodes and you have to use S7 Comm nodes instead. These nodes support a subset of the functiond a TIA portal software supports. For this the netPI and IP address needs to be in the same subnet as you TIA Portal Windows PC and connected to the same Ethernet switch for example. Then the S7comm nodes can access to the PLC at the same time as your TIA portal software.

In contrast of this previous use case is if you want to exchange process data from PLC I/O buffers with a PROFINET IO slave like with Beckhoff IO or Wago IO devices, then you need the fieldbus nodes. The Fieldbus nodes let the netPI simulating IO data that can be exchanged with Node-RED forth and back.

Thx
Armin
You never fail until you stop trying.“, Albert Einstein (1879 - 1955)

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#3
There is one more remark in addition. While cyclic IO goes over 2xRJ45 real-time ethernet ports, the acyclic communication put/get with the S7comm nodes goes over the single RJ45 Ethernet port
You never fail until you stop trying.“, Albert Einstein (1879 - 1955)

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#4
At first thank you very much for the fast reply and the good information.

That is what I already thought. The device delivers just the information from the S7 to other Profinet IO devices over the Fieldbus ports. The s7comm-nodes communicate about tcp/ip and that was my fault. 


I have a further question: for one of my project tasks, I have to find out how the netPI can communicate with an S7 plc via Profinet on the one hand as a device and on the other hand as a master device. What I read is that the netX controller is not able to work as a master device. is that right? 

Thank you!

Marcel
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#5
Yes this is right. netX51 type of chip cannot be a master. It supports device protocol stacks only.

But if you want to let a Rasperry Pi be a PROFINET master (and because netPI is compatible to RPi it works with netPI too) then this is very easy. It goes across the eth0 port using CODESYS SoftPLC. You can test it 2 hours for free then the PLC stops. So you can replace an S7 PLC with a Raspberry Pi or netPI.

Next to PROFINET master, CODESYS can also be EtherNet/IP master or EtherCAT master.

Thx
Armin
You never fail until you stop trying.“, Albert Einstein (1879 - 1955)

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#6
Thank you very much, the information is very helpful!

Marcel
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