System and method for automatically testing analog module used for programmable logic controller (PLC)

Abstract

The invention discloses a system and a method for automatically testing an analog module with a settable input / output (I / O) channel in a programmable logic controller (PLC). The system comprises an upper control computer, a programmable direct current signal source, a digital multimeter, a channel and voltage / current mode switching control plate and a communication interface, wherein the upper control computer sets a testing parameter, issues an instruction to realize output or measurement, receives a test result and makes judgment according to the result; the programmable direct current signal source receives the instruction and the parameter to set the output as a voltage or current mode, sets and outputs a voltage / current signal to an input channel; the digital multimeter receives the instruction to set the measurement as the voltage or current mode, measures the voltage or current signal output by an output channel and returns a measured value to a computer; the channel and voltage / current mode switching control plate switches a test channel and a voltage / current connection mode according to the instruction; and the communication interface transmits the parameter, the instruction and the test result between each device and a tested model. A computer reads the conversion value of the voltage or current measured value of the input channel through the communication interface or transmits a set numerical value to the output channel to convert the set numerical value into a voltage or a current.

Description

technical field [0001] The invention relates to a function and performance test of an analog module of a programmable logic controller (PLC), in particular to an automatic test system and method for the analog module of a programmable logic controller (PLC). Background technique [0002] The analog module of PLC is used to measure the input analog voltage / current and output the corresponding analog voltage / current according to the set value. The analog module generally contains multiple channels, and the channels are divided into two types: Input channels for inputting analog quantities and output channels for outputting analog quantities. The analog module mainly converts the external input analog voltage or current value into the corresponding value in linear proportion through the input channel and performs measurement, and converts the value set by the user into the corresponding analog voltage or current value in linear proportion through the output channel and output....

AI Technical Summary

Problems solved by technology

[0003] When performing function and performance tests on PLC analog modules, it is necessary to test multiple items including conversion error, temperature offset, stability, etc., and analog modules usually have multiple input channels and multiple output channels, so in complete In the case of manual testing, completing the test of an analog module not only has a very huge workload, but also is prone to measurement errors

Images