Bus ID of the bus port. Depending on the bus system, the value is a simple number, an IP address or a combination of letters and numbers. The property in the "Bus data" tab of the property dialog is entered at the single-line network / bus cable-connection points. Describes the address / position the bus master uses to manage a bus port. The property in the "PLC structure data" tab of the property dialog is entered at PLC boxes and describes which bus ID the PLC box has in the connected bus system.

Reference

FunctionPropertyList Class
FunctionPropertyList Members