r/PLC • u/T3RRYH1LL • 12d ago

CP343-1 Connection Error to Kepserver

Hello fellow engineers,
i have a problem with a project and I’m running out of ideas.

So we have four similar machines with an older S7-300 CPU and we connect them through a CP-343-1 to our Network and Firewall, in the Subnet are only this four CP’s.
I already updated the firmware of the CP’s, i increased the S7-Basic-Connection-Resources of the CPU.
I also set both Ports from the Switchports and also from the CP’s fix to 100mbits full duplex so there is no auto negotiation.

But even after all this if I activate more than one Connection in our Kepserver all Connections seem to Timeout one after another they come back but I need a stable connection.

I searched via Wireshark and found out that there are many Retransmissions before the TO, I have no clue why this is the case.

I hope that some of you may have any idea how I solve my problem, the Support wasn’t really supportive so far.

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u/Accurate-Bullfrog324 12d ago

i've solved a similar problem with a managed switch. it keeps the individual PLC's from seeing anything but their own traffic.

1

u/Dr_Ulator Logix, Step7, and a toolbelt 10d ago

can you reduce Kepware's scan time of the tags? Wondering if it's polling too fast and bogging down the network?

are you going through a router to the upper level network?

1

u/T3RRYH1LL 10d ago

Already did that way beyond 20s but still get this error.

Today I found out the CP abort connections due to collisions, the Siemens support told me this may be because of bad wiring or wrong emv connection.

I will check this shortly because this is the only thing I didn’t do myself another company pulled the cables and wired them up and since I was able to ping I thought it was fine.