A method of determining variable trip setpoints at the time of performing a safety analysis on a plant protection system includes: selecting a fixed analysis setpoint including a first analysis setpoint at which safety functions are initiated according to process variables of a power plant, and a first reaching time representing a time required to reach the first analysis setpoint; deriving a variable analysis setpoint satisfying conditions of the first fixed analysis setpoint; and determining a variable trip setpoint by reflecting uncertainty of an instrumentation and control system in relation to the variable analysis setpoint.

A machine state monitoring device is a machine state monitoring device that is intended for a motor drive device of a machine tool. The motor drive device includes: a motor; a converter and an inverter that adjust a power supply voltage; a power failure detection unit that acquires an input voltage of the motor drive device so as to detect a power failure in the motor drive device; and a communication unit that transmits, based on the result of the detection of the detection unit, a time when the power failure is started, and a time when the power failure is completed. The machine state monitoring device includes: a communication unit that receives information of the time when the power failure is started and the time when the power failure is completed from the communication unit of the motor drive device; and a storage unit that stores the information.

A method of determining variable trip setpoints at the time of performing a safety analysis on a plant protection system includes: selecting a fixed analysis setpoint including a first analysis setpoint at which safety functions are initiated according to process variables of a power plant, and a first reaching time representing a time required to reach the first analysis setpoint; deriving a variable analysis setpoint satisfying conditions of the first fixed analysis setpoint; and determining a variable trip setpoint by reflecting uncertainty of an instrumentation and control system in relation to the variable analysis setpoint.

A robot control device configured to control a robot includes a first memory part configured to store work data, a second memory part configured to store restoring data, a calculating part configured to perform an operation instructing process configured to read the work data and generate an operating instruction to the robot, and a data evacuation process configured to determine whether the operation instructing process operates normally, and when the calculating part determines that the operation instructing process does not operate normally, coincide the restoring data with the work data, and an operation controlling part configured to control operation of the robot based on the operating instruction.

A robot control device configured to control a robot includes a first memory part configured to store work data, a second memory part configured to store restoring data, a calculating part configured to perform an operation instructing process configured to read the work data and generate an operating instruction to the robot, and a data evacuation process configured to determine whether the operation instructing process operates normally, and when the calculating part determines that the operation instructing process does not operate normally, coincide the restoring data with the work data, and an operation controlling part configured to control operation of the robot based on the operating instruction.

A machine state monitoring device is a machine state monitoring device that is intended for a motor drive device of a machine tool. The motor drive device includes: a motor; a converter and an inverter that adjust a power supply voltage; a power failure detection unit that acquires an input voltage of the motor drive device so as to detect a power failure in the motor drive device; and a communication unit that transmits, based on the result of the detection of the detection unit, a time when the power failure is started, and a time when the power failure is completed. The machine state monitoring device includes: a communication unit that receives information of the time when the power failure is started and the time when the power failure is completed from the communication unit of the motor drive device; and a storage unit that stores the information.

When a main power supply is shut off and a robot control apparatus is unable to be involved, information on a state of each joint can be recorded at a robot arm alone. A robot arm includes: a plurality of links; a joint connecting the plurality of links to each other; and a sensor that detects a state of the joint. Further, the robot arm includes: a logging device that records output information of the sensor; and a powering unit that supplies power to the sensor and the logging device in a state where a drive power supply of the joint is shut off.