Each of DAW processes and UI devices which are controllers of the DAW processes regularly sends a heartbeat signal including identification information of a music system which the DAW process or UI device belongs to, to a network by broadcast or multicast. The heart beat signal can be transmitted to the network using an Ethernet frame for UDP including the heartbeat signal in the data body, as a heartbeat packet. Based on the received heartbeat signal, it can be distinguished that the DAW process or UI device which sent the heartbeat signal is which of a device or music software process belonging to the relevant music system, a device or music software process belonging to another music system, and a device or music software process not belonging to any music system.