I want to cancel the automatic address allocation for all IO mappings. If I directly set the automatic_iec_address in class ScriptIoMapping to False, the address becomes None. So I reset manual_iec_address with itselfs value. It only work with the Input IOMapping . For output, it reports an error: "Invalid address: The channel type 'Output' requires address type '%Q'." I checked the description file ,both accessRight are total same. Does anyone know what causes this?