The CANopen application profile for lift control systems, also known as CANopen Lift specification, defines the communication interfaces for different virtual devices. This includes call, car drive, and car door controllers as well as input panel, output panel, car drive, car position, load measuring, car door, light barrier, remote data transmission, and power-measuring units. All necessary PDOs for a single-shaft lift control system are defined; some of them are distributed in broadcast other peer-to-peer. For multi-shaft lift control systems, the communication between the controllers is manufacturer-specific. Nevertheless, each device may implement up to eight instances of the application profile, so that it can be used in up to eight lift control systems.