Good day experts,

We observed through NCM S7 diagnostic/ online monitoring through simatic manager, that the CP343-1 lean uses different router/gateway IP address (192.168.2.110) compared to the configured address (192.168.2.107) - please see attached picture for reference.

Does anyone had a similar experience on this problem? Asking for your advise on how to resolve this.

Thanks!

Update as of July 3, 2023:

We tried isolating the CP from the network switch and connected directly to PC, and observed that communication is ok (simatic manager can connecto online HW config and software blocks, as well as online DB monitoring).

However, when we connect the CP to the network switch, and from network switch connect the PC, communication from simatic manager to PLC doesn't work.

Please note that for WinCC communication to PLC with the same PC, communication works fine all throughout (isolated from network setup and networked setup).

Network switch (Layer 3) have the same subnet IP with the PLC and PC.

We're suspecting some firewall config or gateway settings interfering with the communication?

Please share if you have any similar experience.

Thanks!

Hello jomzki

does a Ping work from PC to CP?

Check if Port 102 is free. disable Anto virus Scanner and firewall for testing. Conect directly from PC to CP, does this work? then the configuration of the switch is the reason... -> test also with an unmanaged switch

Bye Murof

Yes Murof, connecting PC and CP directly is ok.

But connecting to the network (from CP to Network switch, then Network switch to PC), does not work.

Ping tests are all ok with these two setups.

Hello Jomzki

Do you have tested with an unmanaged switch? if this work then there is something blocked in your Network...

Bye Murof

No I was'nt able to test with unmanaged switch, but already confirmed direct connection (only CP and PC connected and without network switch).

It seems that the network switch (Cisco) or the firewall is causing communication problems but can't exactly determine which one. What are your recommendations for this? Thanks!

Hello jomzki

Is the cisco switch administrated by you or a IT department?

In managed switches there should be an integrated webserver with a webbased configuration.

Here you should be able to set rules and settings that have an influence on the network trafic.

bye Murof

Hi Murof,

Yes, cisco switch is managed by our IT team. 

What are the important settings needed to be checked?

Thanks!

Hello jomzki

as I wrote only Port 102 should be used for S7 communication

if it works with unmanaged switch then something should be diffeent or blocked

Bye Murof

Update 2024:

Further observations: Cannot connect to the PLC online thru simatic manager when WinCC Runtime is activated. 

Our temporary work-around  is to deactivate WinCC Runtime first.

So our problem is WinCC and Simatic Manager cannot connect to the PLC simultaneously on the same computer through TCP/IP. Other work around is to connect from simatic manager using MPI cable but unfortunately the cable length is limited.

Wondering how this happened and how to solve this? This setup has been working since 2013, only until 2023 have we encountered this issue.

Thanks!