EtherCAT Slave Implementation in Testbed.CONNECT: AVL manufactures various testbeds such as engine- and powertrain-testbeds as well as the associated automation. To connect testbeds or individual automation components AVL uses EtherCAT for a fast and stable communication. The automation system is defined as an EtherCAT master. If two automation systems are now connected with each other, special couplers are required, since a Master/Master-connection is not provided according to the EtherCAT protocol. To eliminate these additional components, an EtherCAT slave implementation is to be integrated into the automation system. For the implementation, a special EtherCAT slave hardware must be used, which communicates with the system via an application.