Abstract: An industrial control system implementing a multi-tasking operating system employs a primary and secondary controller each having a processor and an I/O data table. The processors are configured to execute one or more priority ranked programs. A tracking of changes in the I/O data table of the primary processor is used to independently track changes to controller specific data that has been changed and program specific data that has been changed and to transmit controller specific data that has been changed by any program and program specific data that has been changed only for completed programs to the secondary processor.

Abstract: An industrial control system implementing a multi-tasking operating system employs a primary and secondary controller each having a processor and an I/O data table. The processors are configured to execute one or more priority ranked programs. A tracking of changes in the I/O data table of the primary processor is used to independently track changes to controller specific data that has been changed and program specific data that has been changed and to transmit controller specific data that has been changed by any program and program specific data that has been changed only for completed programs to the secondary processor.

Abstract: A system and method for industrial control I/O forcing is provided. The invention includes a processor, shared memory and an I/O processor with cache memory. The invention provides for the cache memory to be loaded with I/O force data from the shared memory. The I/O processor performs I/O forcing utilizing the I/O force data stored in the cache memory. The invention further provides for the processor to notify the I/O processor in the event that I/O force data is altered during control program execution. The invention further provides for the I/O processor to refresh the cache memory (e.g., via a blocked write) after receipt of alteration of the I/O force data from the processor.

Abstract: A system and method for industrial control I/O forcing is provided. The invention includes a processor, shared memory and an I/O processor with cache memory. The invention provides for the cache memory to be loaded with I/O force data from the shared memory. The I/O processor performs I/O forcing utilizing the I/O force data stored in the cache memory. The invention further provides for the processor to notify the I/O processor in the event that I/O force data is altered during control program execution. The invention further provides for the I/O processor to refresh the cache memory (e.g., via a blocked write) after receipt of alteration of the I/O force data from the processor.

Abstract: A bus structure for interconnecting the modules of an industrial automation controller includes DATA lines and associated control lines that enable interface circuits on each module to transfer frames of data. Modules connected to the bus structure support data transfers of differing widths and differing speeds, and interface circuits within each module automatically adapt to data width and speed differences between communicating modules. During a first bus cycle of each transfer, sending and receiving modules negotiate a bus width and clock speed to be used for the transfer by asserting their respective width and speed codes onto a set of wired-or status lines. After the first bus cycle, the status lines are then used for communicating alternate functions between the participating modules.