Brake system of a commercial vehicle comprising a) a first control unit which is connected by a bus system to an electro-pneumatic wheel brake unit which is connected to a service brake chamber of a combination brake cylinder , and which electrically controls the wheel brake unit via the bus system in order to control a pneumatic brake pressure for the service brake chamber of the combination brake cylinder to correspond to a brake demand, b) a second control unit which is connected via the bus system to the electro-pneumatic wheel brake unit and which electrically controls the wheel brake unit via the bus system in order to control a pneumatic brake pressure for the service brake chamber of the combination brake cylinder to correspond to a brake demand, the second control unit also electrically controlling an electro-pneumatic parking brake valve device for generating a parking brake pressure to correspond to a brake demand, wherein the parking brake valve device is connected via a pneumatic parking brake line to a spring brake chamber of the combination brake cylinder for transmitting the parking brake pressure, c) wherein ca) a service brake unit is connected via brake demand signaling lines both to the first control unit as well as to the second control unit for transmitting a brake demand and/or cb) a parking brake actuation unit is connected by parking brake demand signaling lines both to the first control unit as well as to the second control unit for transmitting a parking brake demand. a) a first control unit which is connected by a bus system to an electro-pneumatic wheel brake unit which is connected to a service brake chamber of a combination brake cylinder , and which electrically controls the wheel brake unit via the bus system in order to control a pneumatic brake pressure for the service brake chamber of the combination brake cylinder to correspond to a brake demand, b) a second control unit which is connected via the bus system to the electro-pneumatic wheel brake unit and which electrically controls the wheel brake unit via the bus system in order to control a pneumatic brake pressure for the service brake chamber of the combination brake cylinder to correspond to a brake demand, the second control unit also electrically controlling an electro-pneumatic parking brake valve device for generating a parking brake pressure to correspond to a brake demand, wherein the parking brake valve device is connected via a pneumatic parking brake line to a spring brake chamber of the combination brake cylinder for transmitting the parking brake pressure, c) wherein ca) a service brake unit is connected via brake demand signaling lines both to the first control unit as well as to the second control unit for transmitting a brake demand and/or cb) a parking brake actuation unit is connected by parking brake demand signaling lines both to the first control unit as well as to the second control unit for transmitting a parking brake demand. ca) a service brake unit is connected via brake demand signaling lines both to the first control unit as well as to the second control unit for transmitting a brake demand and/or cb) a parking brake actuation unit is connected by parking brake demand signaling lines both to the first control unit as well as to the second control unit for transmitting a parking brake demand. <EOS>