Judgment method for communication stability of network system, main unit, slave unit and relay station

Abstract

A method of judging communication stability is provided for a network system including a master unit forming a programmable controller and a slave connected to a network. The master unit transmits to the slave a distorted test pattern formed by distorting a standard test pattern to a specified distortion level. If this distorted test pattern is normally received by the slave, a response is returned from the slave to the master unit. If the mater unit receives this response normally, it is judged that this network system has communication stability corresponding to this specified distortion level.

Description

technical field [0001] The invention relates to a method for judging communication stability of a network system, a master unit, a slave unit and a relay station. Background technique [0002] PLC (programmable logic controller) used in FA (factory automation) inputs ON / OFF information of input devices such as switches and sensors, and executes logic operations according to sequence programs (user programs) written in rad-language, etc. After that, the PLC performs control by outputting ON / OFF information signals to output devices such as relays, valves, and actuators according to the obtained calculation results. [0003] As one aspect of the related PLC, a plurality of components generated for each function are prepared and constituted by electrical and mechanical connections. As units for configuring the relevant types, there are various units such as a power supply unit, a CPU unit, an I / O unit, and a main unit. [0004] In addition, the master unit is connected to a c...

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Problems solved by technology

[0011] However, in the invention shown in the above-mentioned Patent Document 1, although it is possible to judge whether it is good or not to a certain extent, it is still impossible to know the level of the field bus (how much margin there is for the boundary where communication cannot be performed).

[0012] In addition, even though it is known that there are various restrictions, in fact, in order to satisfy each restriction, users must stock various wire rods, which will lead to an increase in cost, so it is desirable to judge whether the existing wire rods can be used, and use substitutes if there are substitutes. In the above-mentioned Patent Document 1, it is not possible to judge whether the substitution

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