Method for keeping PLC device power-down data

Abstract

The invention provides a method for keeping power-down data. The method is applied to a PLC. The method for keeping the power-down data comprises the steps that a microprocessor is used for erasing the power-down keeping storage space in advance, and when the PLC is powered down, packaged keeping data are written in the storage space which is erased in advance; when the PLC is powered on, comparison is carried out on the data updating situation, then selection is carried out, and the status of the power-down data is kept newest and usable. According to the method for keeping the power-down data, the problem that the power-down data are stored unreliably or are lost in the limited single-board hardware design on an industrial site is effectively solved, the power-down data keeping performance of the PLC is optimized under the situation that original hardware equipment is not changed, and the requirement for storing the power-down data on the industrial site is met.

Description

technical field [0001] The invention relates to a power-down data retention method for PLC equipment, which belongs to the technical field of industrial control. Background technique [0002] PLC (Programmable Logic Controller), programmable logic controller, an electronic system for digital operations, designed for use in industrial environments. It uses a programmable memory for its internal storage program, executes user-oriented instructions such as logic operations, sequence control, timing, counting and calculation operations, and controls various types of machinery through digital or analog input / output. Or production process, is the core part of industrial control. [0003] With the increasing complexity of the industrial production environment, industrial automation products have higher and higher requirements for data recovery after the production environment encounters an emergency, and even require that in the case of an external sudden power failure, the PLC ca...

AI Technical Summary

Problems solved by technology

Patent CN201220171318.2 provides a power-down hold circuit, which is convenient for writing data into flash (flash memory) in time within a certain period of time after the power is disconnected. Since there is no pre-erasing method, and this method only prolongs the The power-off hold time cannot fully guarantee the correctness of the power-off data, but it greatly increases the hardware design cost

Patent CN200710198446 provides a power-down data software repair method. Although there is already a concept of check code, it lacks time-sequence requirements for stored data, and it is difficult to ensure the real-time and accuracy of industrial field data protection.

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