When setting up a web client server in a PCS7 9.1 system, there are a few best practices to consider:

1. Dedicated Web Server: Ideally, it's recommended to use a dedicated server for the web client to ensure optimal performance and security. This helps in isolating the web server from other critical functions and reduces the risk of performance bottlenecks

2. Using the ES as a Web Server: While it is possible to use the Engineering Station (ES) as a web server, this setup can lead to performance issues, especially if the ES is heavily utilized for engineering tasks. If you choose this route, ensure that the ES has sufficient resources (CPU, memory, and network bandwidth) to handle both engineering and web server tasks

3. Redundancy Considerations: Since you have a redundant system, ensure that the web server setup also considers redundancy. This can be achieved by configuring a secondary web server that can take over in case the primary server fails

4. Network Configuration: Proper network configuration is crucial. Ensure that the web server is on the same network as the OS servers and clients to facilitate seamless communication. Also, configure firewalls and security settings to protect the web server from unauthorized access

5. Licensing and Software Requirements: Verify that you have the necessary licenses for the web client and ensure that the software versions are compatible with PCS7 v9.1

6. Testing and Validation: Before going live, thoroughly test the web server setup in a controlled environment to identify and resolve any potential issues. This includes testing the performance, security, and failover mechanisms
   
   Process control system PCS 7 Web Option for OS (V9.1)