Hello Experts,

Since today the connection between PLC and WinCC V7.5 SP2 is not working anymore. And it looks like it has something to do with pw/certificate. I am working on a project for a couple of months, all the time it was working well.

Its a project with a CPU 1513-1 PN with firmware V2.9 that communicates with WinCC v7.5 SP2 Update 11. I update the tags with an export in tia Simatic Scada. In this way the certificate is in the same package.

The CPU diagnostic buffer gives me the following error:

I tried creating a new certificate, created a new tag export and update in WinCC, deleting the password and also disable the "Only allow secure PG/PC and HMI communication". It all dont matter. Does anybody know how to fix this problem?

ElonksuM_SN_BN

Hi SanderBB,

From what I know about this type of error, the message System-initiated session termination means that a client (e.g. PG; Access Point; VPN) has closed the connection to the CPU. The message is often interpreted incorrectly, because the text assumes that the CPU has terminated the connection. Nothing changes in the operating state of the CPU - however, a stop / run or power cycle must be carried out so that the resources are released again.

The behavior can usually occur if an active online connection to the CPU has not been terminated properly, e.g. Close TIA Portal directly instead of disconnecting an existing online connection or if the CPU is accessed via WLAN (connection aborts). If there is a connection loss via WLAN, the next free resource is used until all resources are occupied - then it comes to the above message.

To this end, improvements have repeatedly been incorporated in the current firmware versions of the CPUs and also in the engineering software (TIA Portal).

See link below: Firmware update S7-1500 CPUs including displays and ET 200 CPUs (ET 200SP, ET 200pro) 

It is recommended to update all other components to the latest firmware version.

I have seen this behavior as well but with CPUs and Unified as indicated in the following link: "WinCC Unified: Connection to the CPU terminated, the diagnostics buffer shows "System initiated session termination""

Can you also attach the full diagotic buffer o see what more events we can find in .txt format?

I hope this is the case. information that may be of help to you.

Best regards!

 Hello ElonksuM,

Thank you for your reply. I have added the requested diagnostic. Restarting of the cpu doesnt give the solution. I will upgrade the firmware, maybe this will help, although i do not think this would solve it.

Is there a way to get some diagnostic from the WinCC side?