The KEY-PLUG stores the configuration data of a SCALANCE X-500 or SCALANCE XM-400 component. Additional Layer 3 Routing functions can be enabled by inserting a KEY-PLUG.

In addition to this, if there is a fault on a module, the module can be replaced simply and quickly without needing to reconfigure the replacement device and without specially trained personnel. If a device needs to be replaced, the KEY-PLUG is simply removed from the failed component and plugged into the replacement device. The replacement device now starts up automatically with the device configuration of the failed device.