摘要:
First ends of electrical elements (CR18, CR14, CR17, CR16) forming safety circuits are electrically grounded, and safety circuits (switches 105, 103, 104, 107) are connected between the remaining second ends of the electrical elements and the power supply side (positive (+) side) of the system thereof, so that even if a signal transmitting line in the safety circuit system is grounded, the safety system relay is not excited; that is, it is kept opened, thereby to interrupt of the servo power supply circuit. Further, two relays of hardware system and of software system are provided which transmits an emergency stop state or other abnormal state to the outside. The relay contact means of the two relays are extended outside, so that it is detected with an external control board whether the relays are opened or closed, thereby to detect whether or not the contact means are fused.