The Loadable Firmware (LFW) from Hilscher includes the protocol stack and real-time kernel rcX. The firmware can be seen as a "black box" and is useable in so-called "companion chip" solutions. The Firmware has easily to be transferred to the netX so that he understands the particular protocol. Thus, no software development on the netX itself is necessary, therefore the time to market is shortened. The firmware is configured by a host controller via the dual-port memory of the netX. The configuration data is transmitted by a mailbox system either directly over the protocol API or over a configuration file created with SYCON.net. Is the protocol stack configured, he provides cyclic and acyclic data at the host interface.