Abstract: A safety PLC includes an I/O module to which a safety device for detecting a predetermined condition at any time is connected, a CPU module that executes a safety program for managing the I/O module, and a communication unit that interconnects the I/O module and the CPU module with each other. The CPU module includes: a PIN code memory that stores a PIN code for authenticating that the safety program satisfies a predetermined standard; a PIN code input unit that allows a user to designate the PIN code; a program auto-creating unit that automatically creates the safety program; and a program authentication unit that puts the safety program into an executable condition when the PIN code designated by the user coincides with the PIN code stored in the PIN code memory.

Abstract: A safety PLC having duplex power supply circuits, includes: a first output-stage transistor; a first DC power supply that drives the first output-stage transistor; a second output-stage transistor; a second DC power supply that drives the second output-stage transistor; a signal transfer path that includes a resistor and connect the first output-stage transistor to the second output-stage transistor; and a pair of overvoltage protection units, each of which is disposed between a pair of output terminals of the corresponding one of the first and second DC power supplies and restricts the maximum value of an output potential difference between the pair of output terminals.

Abstract: A contact welding detecting device includes: a relay including a first contact for permitting and breaking transmission of a first DC input potential to a first output and a second contact for permitting and breaking transmission of a second DC input potential; a relay open/close control unit that simultaneously controls to open and close the first and second contacts when welding of at least one of the first and second contacts is detected; a first potential difference detection unit that detects a potential difference between a first point at an input side of the first contact and a second point at an output side of the second contact; and a second potential difference detection unit that detects a potential difference between a third point at an output side of the first contact and a fourth point at an input side of the second contact.

Abstract: The function block memory unit stores a plurality of function blocks by programming each ladder circuit for computing output signals which has to be determined based on input signals from each safety device according to a connection specification of the safety device. The ladder circuit satisfies a predetermined safety standard, and thus, the function blocks satisfying the safety standard are used. The program link unit sequentially links each function block received from the function block memory unit based on the ID number of each I/O module to automatically create the safety program. The corresponding function block can be uniquely determined based on the ID number.

Abstract: A safety PLC includes an I/O module to which a safety device for detecting a predetermined condition at any time is connected, a CPU module that executes a safety program for managing the I/O module, and a communication unit that interconnects the I/O module and the CPU module with each other. The CPU module includes: a PIN code memory that stores a PIN code for authenticating that the safety program satisfies a predetermined standard; a PIN code input unit that allows a user to designate the PIN code; a program auto-creating unit that automatically creates the safety program; and a program authentication unit that puts the safety program into an executable condition when the PIN code designated by the user coincides with the PIN code stored in the PIN code memory.

Abstract: A safety PLC having duplex power supply circuits, includes: a first output-stage transistor; a first DC power supply that drives the first output-stage transistor; a second output-stage transistor; a second DC power supply that drives the second output-stage transistor; a signal transfer path that includes a resistor and connect the first output-stage transistor to the second output-stage transistor; and a pair of overvoltage protection units, each of which is disposed between a pair of output terminals of the corresponding one of the first and second DC power supplies and restricts the maximum value of an output potential difference between the pair of output terminals.

Abstract: A contact welding detecting device includes: a relay including a first contact for permitting and breaking transmission of a first DC input potential to a first output and a second contact for permitting and breaking transmission of a second DC input potential; a relay open/close control unit that simultaneously controls to open and close the first and second contacts when welding of at least one of the first and second contacts is detected; a first potential difference detection unit that detects a potential difference between a first point at an input side of the first contact and a second point at an output side of the second contact; and a second potential difference detection unit that detects a potential difference between a third point at an output side of the first contact and a fourth point at an input side of the second contact.

Abstract: The function block memory unit stores a plurality of function blocks by programming each ladder circuit for computing output signals which has to be determined based on input signals from each safety device according to a connection specification of the safety device. The ladder circuit satisfies a predetermined safety standard, and thus, the function blocks satisfying the safety standard are used. The program link unit sequentially links each function block received from the function block memory unit based on the ID number of each I/O module to automatically create the safety program. The corresponding function block can be uniquely determined based on the ID number.

Abstract: In a numerical control system, a plurality of machine tools are provided each having a tool spindle, a tool magazine for storing primary tools along with spare tools respectively associated with some of the primary tools, and a tool changer for changing tools between the tool spindle and the tool magazine. A system control host computer included in the system divides the operational period of each machine tool into a plurality of operational period sections and calculates prospective used times of primary tools which are programmed to be used on the tool spindle in accordance with at least one numerical control program within each of the operational period sections. The host computer then estimates primary tools whose lives will expire within each operational period section, based upon cumulative past used times, the prospective used times and life times of the primary tools and searches for tool number data of spare tools associated with the estimated primary tools.

Abstract: A numerical control system is provided wherein numerical controllers associated with machine tools are respectively coupled to auxiliary controllers communicating with a host computer. Each auxiliary controller has a memory for storing revision values which respectively correspond to primary and spare tools being stored in a tool magazine of the associated machine tool. When a spare tool is attached to a tool spindle of the associated machine tool in place of a primary tool, each auxiliary controller reads out a corresponding revision value from the memory and transfers it to the associated numerical controller. Thus, a corresponding one of tool dimension compensation values being stored in a memory of the associated numerical controller is revised or modified by the revision value transferred thereto so as to adapt itself for the spare tool being used on the tool spindle.

Abstract: A tool position offsetting system for a spare tool, including a tool life detecting device provided for detecting a broken or substantially worn tool and for replacing the same by a spare tool, and a detecting device which detects whether the spare tool is inserted in the tool spindle. If the detecting device makes a detection, an input controlling circuit applies several signals to a numerical controller so as to instruct the same to introduce the dimensional data for the spare tool into the memory of the numerical controller, resulting in amending the offset data stored in the memory before a machining operation. After the machining operation, the input controlling circuit applies several signals so as to remove the dimensional data from the memory, resulting in restoring the tool offset data to its original setting.

Abstract: An index apparatus for a rotary table comprises first and second index plates connected to a driving motor. First and second switches are provided for generating first and second signals in cooperation with the first and second index plates each time the rotary table is rotated a unit angle. Third signal generating circuit is connected to the first and second switches for generating third signals, each of which is generated when the second signal is generated and disappears when the first signal disappears. Control circuit is provided for counting the number of the third signals to thereby stop the rotary table at a desired angular position when the number reaches to a preset number.

Abstract: A data transfer system in which a programmable sequence controller, a computerized numerical controller and a pair of data transfer devices are associated respectively with the controllers. Each of the transfer devices includes a data memory and a first read-out and write-in circuit for exchanging control data between the data memory and the associated one of the controllers. Each of the transfer devices further includes a second read-out and write-in circuit which is enabled to operate when the first read-out and write-in circuit is inoperative, for exchanging control data between the data memory and the other controller, so that the control data is transferred from the sequence controller to the numerical controller, and vice versa.

Abstract: A cam grinding machine rotates a workpiece by using a servomotor which is capable of being rotated at a variable speed. A memory device stores data of rotational speeds of the workpiece corresponding to angular positions thereof in order to maintain the circumferential speed of the workpiece constant. A detecting device detects an angular position of the workpiece. A counter is responsive to the detecting device and reads out rotational speed data stored in the memory device in order to apply the same to the servomotor.

Abstract: In an automatic tool change apparatus, numbers of tools stored in respective tool holding devices mounted on a magazine and held in a spindle are identifiable whether the tools are large or small ones. A combination of a tool held in the spindle and a tool commanded by NC data is discriminated to selectively perform a normal or special cycle of a tool change operation.