To read respective values as updated of a plurality of variables synchronization of which respective values is ensured while tasks are being carried out in a multi-tasking manner, a PLC 10 reads respective values as updated of variables A to C in such a manner as to complete reading the respective values as updated of the variables A to C during a time period from (i) a time point of a start of a single instance of a cycle of a task which cycle is shortest to (ii) a time point of an end of the single instance of the cycle.

A high availability industrial automation system in disclosed. The system has a primary industrial automation controller, a secondary industrial automation controller, and a communication network connected to the primary industrial automation controller and the secondary industrial automation controller. The primary industrial automation controller includes a processor and a memory configured to store a plurality of instructions, a plurality of automation tasks, input/output (I/O) data, and internal storage data. The processor is operative to execute the plurality of instructions to cross load information from the primary industrial automation controller to the secondary industrial automation controller. The cross loading of information can be less than the maximum amount of communicable information capable of being cross loaded. Also disclosed are methods of communicating over the high availability industrial automation system.

A configuration of control device capable of linking control applications even in a control system that combines a control device with another control device is provided. A first control device includes: a first program execution part outputting a first control command at every first cycle; a parsing part parsing at least a part of a first application program at every second cycle to sequentially generate an internal command; a command calculation part outputting a second control command at every first cycle according to the internal command generated by the parsing part; and an arbitration part managing a parsing process performed by the parsing part. The arbitration part adjusts an output timing of the second control command according to the internal command generated by the parsing part in response to notification of a timing from the second control device.

To read respective values as updated of a plurality of variables synchronization of which respective values is ensured while tasks are being carried out in a multi-tasking manner, a PLC 10 reads respective values as updated of variables A to C in such a manner as to complete reading the respective values as updated of the variables A to C during a time period from (i) a time point of a start of a single instance of a cycle of a task which cycle is shortest to (ii) a time point of an end of the single instance of the cycle.

A high availability industrial automation system in disclosed. The system has a primary industrial automation controller, a secondary industrial automation controller, and a communication network connected to the primary industrial automation controller and the secondary industrial automation controller. The primary industrial automation controller includes a processor and a memory configured to store a plurality of instructions, a plurality of automation tasks, input/output (I/O) data, and internal storage data. The processor is operative to execute the plurality of instructions to cross load information from the primary industrial automation controller to the secondary industrial automation controller. The cross loading of information can be less than the maximum amount of communicable information capable of being cross loaded. Also disclosed are methods of communicating over the high availability industrial automation system.

A programmable controller periodically controls a plurality of external devices. The programmable controller includes a temporary memory, a working memory, and a control unit. The control unit transmits request packets to each of the external devices, the request packets requesting transmission of device data to be used in control of the external devices, the external devices being targets to be subjected to synchronization control, acquires the device data from response packets received from the external devices in response to the request packets, and stores the acquired device data into the temporary memory, and writes the device data stored in the temporary memory into the working memory on the condition that the respective response packets in response to the request packets transmitted within the same control period are received from the external devices.

A configuration of control device capable of linking control applications even in a control system that combines a control device with another control device is provided. A first control device includes: a first program execution part outputting a first control command at every first cycle; a parsing part parsing at least a part of a first application program at every second cycle to sequentially generate an internal command; a command calculation part outputting a second control command at every first cycle according to the internal command generated by the parsing part; and an arbitration part managing a parsing process performed by the parsing part. The arbitration part adjusts an output timing of the second control command according to the internal command generated by the parsing part in response to notification of a timing from the second control device.

A programmable controller periodically controls a plurality of external devices. The programmable controller includes a temporary memory, a working memory, and a control unit. The control unit transmits request packets to each of the external devices, the request packets requesting transmission of device data to be used in control of the external devices, the external devices being targets to be subjected to synchronization control, acquires the device data from response packets received from the external devices in response to the request packets, and stores the acquired device data into the temporary memory, and writes the device data stored in the temporary memory into the working memory on the condition that the respective response packets in response to the request packets transmitted within the same control period are received from the external devices.

An automation device is provided, which comprises an operating system having a first system clock and a communication system having a second system clock. The first system clock is intended to control a system time cycle of the operating system, and the second system clock is intended to control a system time cycle of the communication system. Furthermore, the first system clock and the second system clock are synchronized in time.