Safe PLC, sequence program creation support software, and sequence program judgment method

Abstract

There is provided sequence program creation support software in a safe PLC capable of rewriting a sequence program. According to input device type information containing first type information indicating that safety is guaranteed for each input device or second type information indicating that safety is not guaranteed and the sequence program as an object, the sequence program creation support software judges whether the output unit corresponding to the sequence program is configured in such a way that safety is guaranteed or not and distinctly displays the judgment result.

Description

technical field [0001] The present invention relates to a safety PLC capable of rewriting a sequence program that combines a plurality of input devices to control an output device, creation support software for the sequence program written in the safety PLC, and a method for judging the sequence program. Background technique [0002] In the past, PLC (Programmable Logic Controller) was generally used in the production line of factories, etc., to input signals related to the conduction state (ON or OFF information) from various input devices (switches, sensors, etc.), and to use various input devices Combine the sequence program in the desired mode (serial or parallel combination) to control (output ON or OFF signal, etc.) output devices (relays, motors, etc.). [0003] Also, when creating a sequence program in which any combination of input devices arbitrarily selected from various input devices is connected in series or in parallel, the user usually creates a ladder circuit...

AI Technical Summary

Problems solved by technology

[0010] In the conventional technology described in Patent Document 1, the reliability of the calculation results can be improved by calculating the sequence programs created by multiple CPUs and comparing the results, but the security of the sequence programs themselves cannot be improved.

[0011] In addition, as another conventional technique, there is a technique in which security is set for each input device in advance, and when a sequence program (ladder circuit, etc.) Secure Input Devices

However, it only shows whether the individual input device is safe, and whether the output of the sequence program is a safe output has to be determined manually by the user, which takes a lot of labor.

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