Hi Sowma,

You can only work with fault tolerant connections on the ISO protocol...it does not work on TCP/IP.

Below is made clear when you use ISO (MAC) and when you use TCP/IP:

Normally plant bus communication is through ISO protocol, but you can use TCP/IP under the following conditions:

• Joint terminal and plant bus for small plants

• Routing via subnets required

• Using an automation system with integrated Ethernet interface

• Using a NTP network for time synchronization

• Monitoring network components on the plant bus for asset management

• Operating gateways on the plant bus

Use the ISO protocol under the following conditions:

• Configuring fault tolerant connections

• Time synchronization based on the Simatic procedure