output lo of the fourth lrc 44 if however one of the dasd slots 88 of the first bank of four dasd 58 and the second bank of four dasd 60 includes a dasd tray 24 then one of the first bank of four dasd 58 and the second bank of four dasd 60 generates an include group selection signal in response to the include group selection signal the third signal is output at the local output lo of the third lrc 52 and received at the input i of the seventh lrc 56 if one of the dasd slots 88 of the second bank of eight dasd 48 includes a dasd tray 24 then the second bank of eight dasd 48 outputs an include group selection signal in response to the include selection signal the seventh lrc 56 outputs the third signal at its local output lo to the second communication path 13 of the second bank of eight dasd 48 the third signal then returns via the second communication path 13 of the second bank of eight dasd 48 to the local input li of the seventh lrc 56 the seventh lrc 56 outputs the third signal at its output o to the second communication path 13 of the second bank of four dasd 60 alternatively if none of the dasd slots 88 of the second bank of eight dasd 48 includes a dasd tray 24 then the second bank of eight dasd 48 generates an exclude group selection signal in response to the exclude group selection signal the third signal received at the input i of the seventh lrc 56 is directly output at the output o of the seventh lrc 56 thus bypassing the second bank of eight dasd 48 the third.