Amount of tags accessible - Siemens

Hi all,
We have a current project accessing tags from a 1500 Siemens PLC. The supplier had to change the configuration in order to be able to access those data (pull/get, optimized block access turned off, etc).
It is working fine, we use around 50 tags.

Now we are thinking on our second project and asking the supplier from beginning the configurations and which tags we want to access. They have told us that this second project is bigger and more complex, so the access to those amount of tags needed may cause failure or a slow performance of the PLC.
They say that will be because off the configurations (optimized block access disabled).
If they don’t set this off, is there some alternative to access the data from de PLC?
They suggest to connect the variables through the Siemens OPC_UA, but I’m not sure if it’s possible or how could we do it.
All that I’ve read in the documents and forum is that the only way with Siemens PLC is with that configuration. But I’ve found this post ( Amount of tags in an Ignition project - General Discussion - Inductive Automation Forum where @Sanderd17 said:

Siemens and Ignition works good enough. If you use a recent S1500 series, you can communicate over OPC-UA, so you get all the benefits of browsing and easy configuration. You should limit what you make available over OPC-UA tough (it’s a checkmark you can enable per data point). Otherwise the PLC may choke.

For other Siemens PLCs, you have to use the Siemens driver, which requires you to type the addresses yourself (or generate them in some way if there’s some logic in the addresses).

I’m not sure how many tags we’ll need, but surely not more than 1k. This could really collapse the PLC?

PD: Edit with more info from the supplier about what they’d like to use. They ask to use the OPC_UA Server of the own PLC, not the libraries Libnodave that use Get/pull.

For (some) Siemens PLCs you have two main options for connectivity with Ignition.
You can use our driver, which uses Siemen’s proprietary network protocol for communication, and has some limitations.
Or you can use the Siemen’s PLC’s on-board OPC-UA server, which means Ignition just acts as an OPC-UA client. Instead of connecting as a device in Ignition, you would create an additional OPC-UA connection.

There will be some additional overhead on the PLC for this, because you’re asking it to “translate” to a different protocol, in addition to the baseline CPU overhead for network communication. I would say that the general advice to limit how much data your fetching, be considerate with your scan rates, etc, applies as much as it does on any PLC.

If I’ve understood correctly, to avoid the config of disable optimized block access we can create an additional OPC connection. But this can affect the performance of the PLC and make it slower as well because it has to translate to a different protocol.

Is that right? If so, we’ll need to ask to Siemens support to know how much overloaded could be the PLC with the configs needed and the requirements of our system.

thanks PGriffith