QUESTION:  
What function does the C-PLUG have with network components and SIMATIC Cps ?

ANSWER:  
The C-PLUG is a removable medium that supports rapid device change without having to configure the replacement device if there is a fault. All you do is remove the C-PLUG from the failed device and insert it in the replacement device. The replacement device then starts up automatically with the same configuration as the failed device.

The C-PLUG can usually be used as an option, in other words the devices can also be operated without C-PLUG.

In the case of some S7 CP modules, such as the CP 443-1 Advanced, the C-PLUG is part of the delivery package and is required for the complete scope of functions of the components concerned