Programmable controller

Abstract

A programmable controller has a multi-purpose processor such as an MPU and an application specific control device such as an ASIC (application specific integrated circuit). When the MPU requests the ASIC to execute a user program and the ASIC is activated, the MPU executes an event process while the ASIC executes the requested user program. When the MPU requests the ASIC to execute a DMA transfer process in an input / output refresh process and the ASIC is activated, the MPU executes an event process while the ASIC executes the requested DMA transfer process.

Description

[0001] This is a divisional of application Ser. No. 10 / 109,541 filed Mar. 27, 2002, currently pending.BACKGROUND OF THE INVENTION [0002] This invention relates to a programmable controller, and more particularly to a programmable controller adapted to concurrently carry out a peripheral service process (event processing) for a peripheral component such as a host computer and a communication unit while carrying out the execution of a user program or an input / output refresh process such that the cycle time of the CPU unit of the programmable controller can be reduced and its response is improved. The invention also relates to a method of controlling such a programmable controller. [0003] In general, a programmable controller is structured as an assembly of an I / O unit connected to sensors, switches and actuators, a CPU unit for executing a preset user program and a communication unit for communicating with a host system through a network. In the case of a middle-sized or small-sized p...

AI Technical Summary

Benefits of technology

This design reduces cycle time by allowing the MPU to free up time for event processing while the ASIC handles user program commands, enabling faster response times and improved system responsiveness.

Problems solved by technology

In other words, a quick event response cannot be achieved.

When a complicated application command is executed, however, it becomes necessary to develop and design a dedicated hardware circuit for the purpose and it is difficult to realize it on an ASIC.

The speed of its software operation, however, is not as great as the operation speed of a hardware circuit.

Thus, unless the execution of the user program and the I / O refresh process is completed, the event process cannot be initiated.

Even if it is desired to carry out a peripheral service process with high priority, it cannot be done and a quick event response is not available.

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