An apparatus and method for interrogating and automatically identifying a radio-frequency tagged surgical instrument tray and its contents of RFID-tagged surgical instruments are disclosed. A rope is affixed to and extends along the gas line and has an end affixed to the cuff member. Similarly, each of the edges may be assigned a weight value which may indicate the probably the edge will be traversed during traversal of the directed graph. The machine will shutdown if the critical parameters are determined to be beyond the shutdown values.