Siemens S7-300 can connect directly but not through switch

Hello,
I'm not a Siemens person so I'm a little confused what can be missing in siemens ethernet configuration.

I have S7-300 with 343 module and i want it to communicate with KepServer (which is on another subnet).

Right now i tested connection by connecting directly S7-300 and my laptop's virtual machine kepserver and it worked but when i connected it through switch (without changing ip addres of my laptop) i couldnt connect to it. I was still able to ping it. What should i check? what can be missing in Siemens configuration? If i can ping it (even in different subnet) it seems that ip and gateway is set correctly...

IT department of course say there is something wrong with siemens configuration but i believe it can be something with switch. I need to prove that it's not siemens configuration related. Please help me.

Is it a managed switch?
Try a non-managed switch for starters.

You say you're trying to do routing. Is there any NAT involved, or is it straight layer 3 switching? Is there a firewall involved? Port 102 must be open.

If the IP address, subnet mask, and gateway are set correctly on the cp343 you are plugged into, then I don't think there is much else to worry about configuration-wise.

Also.. If I am not mistaken, if you are using a profinet connection for some reason, this will not work if you are routing. It should work with a switch.

Does not seem to apply for your case, but thought I would throw that in.

Boneless makes a good point. Profinet IO communication is layer 2 (MAC address and device name) not Layer 3 (IP address), and therefore does not support routing. This makes for less overhead and faster communication, and I've never heard of a case where it was a good idea to route IO from one network to a PLC in another.

However, an OPC server connection uses ISO over TCP, which is layer 3, and does support routing.

Guys,
It's getting weird. I can telnet to siemens on port 102. I can ping it. IT said they disabled all security on siemens port and my laptop port (on switch). Still I'm not able to read tags...

@rdrast - yes it's managed switch i'll try with not managed
@mk42 - we tested it with all security between used ports disabled - still no go
@boneless - thanks for heads up! but as mk42 stated OPc server use tcp so it's should be easly routable

I conntacted Kepware support but after answering their questions they say it's network related and they can't help me much.

mk42 said:

If the IP address, subnet mask, and gateway are set correctly on the cp343 you are plugged into

Click to expand...

Did you check this. Especially the gateway (aka. Router) ?

Chcecked


I can't read tags even when i'm in same subnet with my laptop :/

Can you ping the router address from the end of the ethernet cable that goes to the CP343-1 module.

Yes i can.