blank condition has occurred the programmable rotary limit switch 52 and associated relay 57 hold the turned blank fault indicator relay 54 energized during a time period or portion of a machine cycle that the tool case 31 is ordinarily displaced by proper engagement of a blank 27 in the tool 29 the relay 57 serves to maintain the fault indicating relay 54 on i e latched in at this portion of a machine cycle in contrast the programmable rotary limit switch 52 turns off the relay 57 for a time period or segment of a machine cycle before normal displacement of the tool case 31 and the normal turn off of the related relay 56 to thereby create a check window and detect premature actuation of the proximity sensor 47 assumed to be the result of a turned blank as soon as neither relay 56 or 57 is energized the power to the coil of relay 54 is removed and this relay de energizes which action also opens its own contact at the same time the signal to the plc 51 disappears which condition the plc recognizes as a sensed turned blank tbm fault and the crankshaft 12 is stopped by the plc with a signal to the clutch brake 14 in the process of stopping the crankshaft 12 even if either relay 56 or 57 are re energized relay 54 will not latch in again.