Custom script to get data from an OPC UA on a S7-1500

[Viktor_k83]

Working on a home-brew SCADA and trying to get data from an OPC UA server provided by the manufacturer on a S7-1500. I use UA Expert as a reference to get the structure but have to write my own script. After a few hours, I was able to figure out the path and access to objects/tags (if I may call them this way) but am not able to read the attributes - getting no properties. I'm confused by expanding errors before the tags (e.g. DoorX_Locked) but in reality, there is nothing under level when I click on the tags and the window then show all the attributes. Tried different referencetypeIDs - 47, 46, null, I believe, 35, too - but it then goes into infinite loop as there are too many tags on the server. I just need to test and extract one specific tag for now, and its attributes in a .json file. The script is JS based but I can try Py for the test purposes if it handles something differently. I'm not really a pro in OPC UA.

[DanW]

Back in the late 1990's when OPC DA was gaining steam, the hotel meeting room seminars by the OPC Foundation provided an overview on use and applicability, but the nitty gritty details about the protocol were available by membership, typically corporate membership, given the market.   

That appears to be the case for OPC UA, reading the last line on the Developer Tools page on their web site:

https://opcfoundation.org/developer-tools/

[Mark-]

4 hours ago, DanW said:

Back in the late 1990's when OPC DA was gaining steam, the hotel meeting room seminars by the OPC Foundation provided an overview on use and applicability, but the nitty gritty details about the protocol were available by membership, typically corporate membership, given the market.   

That appears to be the case for OPC UA, reading the last line on the Developer Tools page on their web site:

https://opcfoundation.org/developer-tools/

Right the original DA stuff you had to be a member, $$$, to get the specification and code examples, tools, etc.. For UA it changed, the specification is available to the public and you must be a member $$$ to get the code/tools/examples/etc.. 

[Viktor_k83]

23 minutes ago, Mark- said:

Right the original DA stuff you had to be a member, $$$, to get the specification and code examples, tools, etc.. For UA it changed, the specification is available to the public and you must be a member $$$ to get the code/tools/examples/etc.. 

5 hours ago, DanW said:

Back in the late 1990's when OPC DA was gaining steam, the hotel meeting room seminars by the OPC Foundation provided an overview on use and applicability, but the nitty gritty details about the protocol were available by membership, typically corporate membership, given the market.   

That appears to be the case for OPC UA, reading the last line on the Developer Tools page on their web site:

https://opcfoundation.org/developer-tools/

And now I made everything work with CGPT and GEMINI. This was really one of the trickiest parts on my machine polling back-end and it took I'd say, a few days in total. Mostly because of how and where variables are nested inside the machine program. And their structural categories. What really helped me were OPC UA expert and KEP Server - reading their logs and then feed them to AI models. Then read network logs and decode them, too. AIs fall in loop often times, so you'd have to be good in the troubleshoot flow )

p.s attached is my dashboard layout. The machine back-end -  polls OPC UA, FINS and cIP machines every 20 secs and stores raw data in the SQL DB. The dashboard back-end handles events and then sends to the front-end. Now working on integration with Microsoft Teams to have alerts on mobile devices and other visual effects - e.g. machines live map

[Hati]

KEP server and NodeRed have a direct S7 driver to read the DB's without even configuring OPC server to the PLC. And when the PLC has OPC server configured, the data structure is defined in the PLC and then you receive the same structure to the OPC client software, so it should be really staight forward.

[Viktor_k83]

2 hours ago, Hati said:

KEP server and NodeRed have a direct S7 driver to read the DB's without even configuring OPC server to the PLC. And when the PLC has OPC server configured, the data structure is defined in the PLC and then you receive the same structure to the OPC client software, so it should be really staight forward.

Possibly if you have a ready client, but all my scripts were custom js. Besides, I was only given the OPC server address as these machines are still on the manufacturer support. So I had to trace logs and values to read the nesting, to say the least. For some reason, direct addressing similar to what OPC Expert read from the server - didn't work for me.

But, again, this was my first experience with OPC UA at all.

Edited July 6 by Viktor_k83

[Hati]

So the PLC has OPC UA server configured and running? Then the OPC client should directly see the lags offered by the OPC UA server.