An expander coupled between at least a first and second SCSI device for transmitting data and training patterns is provided. The control circuit realizes data write by a set of two types of operations of an operation of erasing data of a first address or an operation of setting a flag value to an invalid state and an operation of writing data to a second address different from the first address or an operation of setting a flag value to a valid state. The monitoring device further makes the organized information explicit, that is, available either locally at the appliances or remotely within or outside the household environment. The moveable plate has an open position, a closed position and a plurality of positions therebetween.