CoDeSys method of reading CSV file (non Excel)

1、 preface

       CSV It's universal 、 Relatively simple file format , By user 、 Business and science are widely used . The most widely used is to transfer table data between programs , And these programs themselves operate in incompatible formats （ It's often private and / Or no standard format ）. Because a lot of programs support some kind of CSV variant , At least as an alternative input / Output format .  If your machine is equipped with  Microsoft Excel Words ,.csv By default, the file is Excel The open .

codesys With file open , File read , Function blocks and libraries written to files , that csv Whether the format of the file can be in codesys Open in , The answer is obvious , Next, let's introduce the specific operation methods .

2、CSV data format

        Comma separated values （Comma-Separated Values,CSV, Sometimes it's also called Character separated values , Because the separator character can also not be a comma ）, Its files store tabular data in plain text （ Numbers and text ）. Plain text means that the file is a character Sequence , It doesn't have to be like Binary numbers The data interpreted like that .CSV A file consists of any number of records , Records are separated by some kind of line break ; Each record is made by Field form , The separator between fields is another character or string , The most common are commas or tabs .

      Let's take a file data as an example to illustrate ： use EXCEL open DATA.CSV file , See the following data ：

We can use Notepad mode to open , You can see the following ：

  By comparison, we can find that , In this case CSV The data from “,” separate , There is no data in the blank space , At the same time, it should be noted that there is a newline between the second line and the first line , The Notepad doesn't show , But in general, we can put CSV Data is treated as a sequence of characters .

 3、 File reading function block

3.1、 File reading function block

codesys To read the file, you need to add 4 Library files , This example USES codesys The software version is V3.5.14.10：

a、SysFile, 3.5.15.0（System）： The library provides access to files
b、SysTypes2 Interfaces, 3.5.4.0（System）： The library provides data formats for accessing files
c、Util, 3.5.15.0（System）： The library provides data type conversion
d、StringUtils, 3.5.15.0（System）： The library contains functions that handle strings

The method of adding library files is not introduced here .

3.2、 Introduction to function block instructions

The file reading function is mainly used  SysFileOpen,SysFileGetSizeByHandle,SysFileRead,SysFileGetPos,SysFileClose Five instructions , The functions are as follows ：

 3.3、CSV Read the basic process

CSV The steps of file reading are as follows ：

a、 adopt SysFileOpen Command to open the file ;

b、 adopt SysFileGetSizeByHandle Get the file character sequence size ;

c、 adopt SysFileRead Read the character sequence once , And sequentially stored in the preset array ;

d、 adopt SysFileGetPos Get file pointer position , Determine whether all data has been read ;

e、 adopt SysFileClose close CSV file , If the file is not closed , Cannot read next time .

f、 Array data processing .

4、 Programming

This example passes ST Language writing

4.1、 Create variables

The variable table is created as follows ： The file path is set according to the actual situation , The path cannot contain Chinese , Otherwise, I can't recognize ！！.

 4.2、 Programming

a、 Read file data

 b、 Data processing

adopt SysFileRead Instructions read out CSV The original data of the character sequence is ASCII Code value , It needs to be transformed , Then merge , Need to avoid " comma "," Carriage return and line change ", And need to pass " comma "," Carriage return and line change " To determine the specific location of the corresponding data , Space limit , Don't explain in detail , The data processing procedure is as follows ：

4.3、 Create a visual view

Use multiple text boxes to create a table corresponding to the data , And connect with the array through text variables , Single button control , The view is as follows ：

  The variables are connected as follows ：

 

 4.4、 Running results

Through the simulation run, we first check the original data , You can use the corresponding ASCII Compare the code table with the original data , give the result as follows ：

  adopt ascii Through comparison and verification, it can be concluded that , There is no problem reading the data .

Then verify the correspondence between the converted data and the table data , The simulation results are as follows ：

 5、 review

Through the above analysis , Programming and verification ,codesys Through the file reading function block, it is completely possible to CSV Read file data , The next article will explore the write function .

It should be noted that ：

1、 Read CSV when , We found that we need to read out all the data , adopt " comma "、" Line break "、" enter " Wait for symbols to determine the corresponding position of all data , So even if we only need one of these data , You also need to read out all the data .

2、 And when the amount of data is large , The read array we build also needs to have corresponding capacity to store , Otherwise, data will be lost . In this case, the amount of data is small , No more than 50 individual , So it has no effect .

In this paper codesys Version is V3.5.14.10, The programs involved can be downloaded from the following address ：

https://download.csdn.net/download/qq_19979629/85196575