I think it may be your PC that doesn’t have enough memory.

...sent from App

I can make sure in the future that I only have 1 instance of TIA running at the moment of download, but actually my laptop with 64GB installed physical memory should be sufficient. For example at the moment of writing I've 3 instances open and run currently with a memory usage of 30%.

0_Einstein

How many profinet devices are connected to the PLC all the time?

Are you using multi-engineering connections to the PLC?

The PLC has currently 56 Profinet devices in it's own network, but also shares his subnet with more than 250 devices. But all the other CPU's in the same subnet from the same type (1517) never have this issue. I took a print screen of the online connections.

Multi-user was used in the beginning of the project, now there is only one engineer online at the time.

0_Einstein

When the www / web server is used, is it logged in / out every time?  Or, do the users do like most people and skip the logout?

If so, once the online connections exceed the available web server connections, it stops accepting new connections.

 I've enabled all useful functions in the web server without a required user level in order to avoid this. On this CPU there are no user-pages running, it's only visited for debugging purposes. That's also the reason why it showed one web connection in my post above since I was visiting the webpage for this at that moment.

0_Einstein

Is 56 PN devices typical of all the other PLCs in the same subnet?

A lot of them are similar, like for instance servo drives. But some of them are also very unique per machine like lasers, robots, webcams, vision, etc. But this is the CPU with the most Profinet devices for sure. Note that this network is not segmented and runs far from efficient but this was a desiccation I didn't make and cannot change anymore. Maybe also good to mention that all CPU's run OPC UA servers as well with an update rate of 1s. Therefore I've configured the communication load at 50% on all of them to make it all as smooth as possible.

0_Einstein

The S7-1517 PLC is quite powerful as you already know.  Is the firmware the same on all the S7-1517's?  What version of TIA Portal is used on most of those PLCs?

No, and that's why it would make a lot of sense to me if we can find a correlation between the FW version in this CPU and these download errors. This CPU is running with FW2.5.0 and the others run either on FW2.6.0 or FW2.6.1. Because we currently have so many different versions and because we already found proof for another issue on another CPU that we could relate to the FW, we will soon upgrade them all to FW2.8.2.

0_Einstein

What version of TIA Portal is used on most of those PLCs?