Dear All,

             We are having a PCS7 multiproject having  18 AS + Redundant OS Server/Clients +9 Single OS Station. We are using S7 fault tolerant connection between all AS-AS and AS-OS communications. We are using Plant bus for AS-OS Server communication and Terminal bus for OS Server - OS Client communication

Both Server were running normally and suddenly   Dataserver02 lost communication at 15:17:17 and at 15:19:43 some AS started to communicate with Dataserver02, while some AS                        (eg, ISBL_Train1_ESD,ISBL_Train1_PCS,ISBL_Train2_ESD,ISBL_Train2_PCS) did not communicate.

Hence at 15:30:50, we deactivated Dataserver02 and upon restarting the server , communication to all AS were re-established. During all these communication issues with Dataserver02, there was no issue with all AS communication with Dataserver01.

Also the S7DOS SCP Remote service is unable to start in Dataserver02

Below are the logs from Wincc/diagnose location taken from S7 Protocol Suite and Wincc_Sys 

Hello arunvt1992

Check the Error Code Details: Error code 0x0000 7002 typically indicates a connection issue with the named connection. Verify the connection status in the S7-Connection Diagnosis and Channel Diagnosis tools to ensure the connection is properly established.

Deactivate Unused Ethernet Ports: Ensure that any unused Ethernet ports on the servers are deactivated. Open ports can sometimes lead to unexpected behavior in redundant systems.

Verify Monitoring Times: Configure adequate monitoring times for fault-tolerant S7 connections using TCP/IP. Recommended monitoring times can be found in the PCS 7 manual. Ensure these settings align with the system requirements.

Restart WinCC Runtime: As observed in historical tickets, restarting the WinCC Runtime on one server at a time can help re-establish the connection. Stop the runtime on the affected server, wait for a few minutes, and then restart it. Repeat the process for the redundant server if necessary.

Check Firmware and Settings: Ensure that the firmware of all components involved (CP, switch, and CPU) is up to date. Also, verify that all components on the plant bus (Scalance switches, CPs, CPUs) have identical settings regarding connection type and transmission rate (e.g., full duplex vs. half duplex).

Inspect Hardware and Network Configuration: Check for hardware issues such as broken cables, dusted switches, or loose connections. Ensure the network configuration is consistent across all devices, including IP subnet settings and default gateway configurations.

Review SQL Server Logs: If SQL Server is involved in the connection, check its logs for any memory or resource-related issues. Ensure the SQL Server has sufficient memory allocated and optimize its task processing settings if needed.

Compile and Download Connections: Recompile and download all connections in NetPro, including the affected named connection. This can often resolve configuration-related issues.