SoraJayson

Can a PLC read another PLC data through router

8 posts in this topic

Good day everyone, before I start asking my question, just want to let you all know that my knowledge with PLC is not that good. I'm still learning on how to do it.

So currently I'm working on a project that trying to obtain data from Omron PLC. I was told that I can't touch the Omron PLC program or modify it. That Omron PLC is connected in an isolated network within a router. Other than adding Network Card on the device, can I use another PLC (any brands) to get the data from that Omron PLC through the router? The communication protocol using here is Ethernet. Can i just tapped into the network and take the data with that way?

Or the other method I'm thinking is that, the Omron PLC will feed the data to a server, can I just obtain that data from server by using OPCUA? I heard there's some PLC that have the OPCUA function, I just make my PLC into the cilent and request the data of that Omron PLC from server through Ethernet. Is this possible?

Please let me know whether my method works or not, thanks in advance guys!

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Ethernet is not "one single protocol", it is a platform involving various type of hardware, media and many many protocols. 

yes some PLC support OPC, some support Ethernet/IP, some support ModbusTCP, or EtherCat or ProfiNet or PowerLink, TCP sockets etc.

One PLC can use same port in different ways. One port has limited resources such as number of connections it can handle.

just because port exists, it does not mean that one can open another connection.

Also Omron makes many PLCs...

so to even begin to think about your request, more info is needed (detailed info). 

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Found this topic over in the general lounge and assuming that SoraJayson leaves some more information as to model and such , I felt the Omron Forum was better suited to answering his questions.

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Found this topic over in the general lounge and assuming that SoraJayson leaves some more information as to model and such , I felt the Omron Forum was better suited to answering his questions.

Sorry, this was my first time using this forum.

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Ethernet is not "one single protocol", it is a platform involving various type of hardware, media and many many protocols. 

yes some PLC support OPC, some support Ethernet/IP, some support ModbusTCP, or EtherCat or ProfiNet or PowerLink, TCP sockets etc.

One PLC can use same port in different ways. One port has limited resources such as number of connections it can handle.

just because port exists, it does not mean that one can open another connection.

Also Omron makes many PLCs...

so to even begin to think about your request, more info is needed (detailed info). 

So the current Omron PLC is using CJ2M-CPU34, there are 2 of the same PLC but the both PLCs are connected to several servo motors (using EtherCat, the rest using Ethernet IP) and both the Ethernet Port of the PLCs are connected to a isolated router network. Only the data that is needed will be sent into the cloud server through the expansion network card of the 2nd CJ2M-CPU34 PLC. The Person in Charge doesn't let me touch/modify the PLC to add a monitoring counter system. 

My plan here is to get a new PLC with Ethernet port to take the data from either 1 of the PLC through the isolated router network, I wonder is that possible? Can I just connect my RJ from my new PLC to the router to get the data from the CJ2M PLC?

or can I try getting a new PLC that able to use OPCUA to act as the client and take the data from the server where the Omron PLC send it data to?

The info this time is detailed? or I'm still lacking something. cause I'm not sure what I'm lacking yet, I will try and get those info if needed.

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Well... That is a tiny bit better, we got one piece of the puzzle but this is still vague for me. 
I have not touched CJ2M in years so i hope Omron gurus here will be able to offer better advice.

At any rate, here is how i see it:
You did mention PLC model but that is more or less it. There is no clear info what are the option cards or interfaces and it is unclear waht you mean when you mention "Ethernet" interface without pinpointing exact product. There is a reason devices have different names (CJ1W-EIP21, CJ1W-ECT21, CJ1W-NCxxx, etc.) even though all of them are using "Ethernet".

Also it is unclear what exact restrictions are that you are facing:
cannot access and see PLC program and configuration offline?
or you can see it but must not make any modifications?
adding hardware options, mapping something new to either Ethernet/IP or EtherCat etc will require write access and modifying project.
Btw. if your management or admin does not want you make changes to PLC, how likely is that you would be allowed to make changes to router configuration? Would htey think this is less of a problem? if so the management is a problem. ;-)
What is the real reason for not allowing modifications? Up-time? Warranty? Training/Competence? Review policies? Backup options (or lack of)? 


PLCs in general support transparent mode which allows access to its memory for example with minimal if any configuration. This is for example how programming software and HMI may be accessing different parts of memory. An example would be host link so maybe a way forward is to create PC program that gets the data out of the PLCs or whatever. This would allow completely bypassing restrictions (and defeating them) since one could also write garbage to PLC memory and still cripple production. Hence my curiosity about validity of restrictions in the first place.


As you can see i have more questions than answers.
 

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On 8/26/2020 at 7:48 PM, SoraJayson said:

Sorry, this was my first time using this forum.

No need to apologize.  My moving the post was not a correction to you, but an attempt to get your query in front of the Omron Guru's that @panic modementions and get you the best response possible.

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