贝加莱PLC。写入后计算新偏移量或如何将数据写入新行

Posted 2023-02-18

【中文标题】贝加莱PLC。写入后计算新偏移量或如何将数据写入新行

【英文标题】：B&R PLC. Calculate new offset after write or how to write data to new line

【发布时间】：2019-07-17 22:04:25

【问题描述】：

我有这个程序可以在 U 盘上创建文件。问题是它只保存一行（重写同一行）。我需要在每个周期后将数据写入新行。我认为它必须与偏移量有关，我需要计算偏移量，因此它不会每次都从 0 开始。这是部分代码

10: DevLink_0.enable := TRUE;
    DevLink_0.pDevice := ADR('Disk');
    DevLink_0.pParam := ADR(cesta_k_USB);
    DevLink_0();

    IF DevLink_0.status =0 THEN
        step :=20;
    END_IF

20: FileCreate_0.enable := TRUE;
    FileCreate_0.pDevice := ADR('Disk');
    FileCreate_0.pFile := ADR('results.csv');
    FileCreate_0();

    IF FileCreate_0.status = 0 THEN
        identification_file := FileCreate_0.ident;
        offset :=0;
        step :=30;
    END_IF

    IF FileCreate_0.status = fiERR_EXIST THEN 
        step :=25;
    END_IF

25: FileOpen_0.enable := TRUE;
    FileOpen_0.pDevice :=  ADR('Disk');
    FileOpen_0.pFile := ADR('results.csv');
    FileOpen_0.mode := FILE_W;
    FileOpen_0();

    IF FileOpen_0.status = 0 THEN
        identification_file := FileOpen_0.ident;
        offset := FileOpen_0.filelen;
        step := 30;
    END_IF

30: data:=INT_TO_STRING(y);
    data:=INSERT(data,'$r$n',LEN(data));
    FileWrite_0.enable := TRUE;
    FileWrite_0.ident := identification_file;
    FileWrite_0.pSrc := ADR(data); 
    FileWrite_0.len := LEN(data); 
    FileWrite_0.offset := offset;
    FileWrite_0();
    

    IF FileWrite_0.status = 0 THEN
        
            step :=40;
       
        END_IF



40: FileClose_0.enable := TRUE;
    FileClose_0.ident := identification_file;
    FileClose_0();

    IF FileClose_0.status =0 THEN
        IF save = FALSE THEN
            step :=50;
        ELSE
            step := 25;
        END_IF
    END_IF

50: DevUnlink_0.enable := TRUE;
    DevUnlink_0.handle := DevLink_0.handle;
    DevUnlink_0();

    IF DevUnlink_0.status =0 THEN
        stav:= 0;
    END_IF

【问题讨论】：

您必须读取文件或获取文件大小，或者在单独的变量中记住大小。

【参考方案1】：

正如评论中已经提到的，您需要在 FileWrite FUB 中相应地设置偏移量。

我通常使用 AS 帮助中的 FileInfo FUB Guid 6eaf42f0-4ce5-44b7-95cb-275ae1c2fac5 来执行此操作。它会告诉你文件是否已经存在以及它的大小。

如果存在，下一步将是 FileOpen，否则是 FileCreate。

最近我在 GitLab 上创建了一个小项目，除此之外，它还在文件中附加了一行：https://gitlab.com/kirni/bur_robotic_sample/blob/master/bur_robotic_sample/Logical/Libraries/TeachLib/Teach.c

代码是 C 语言，但我相信你明白了。

case stTEACH_INFO:

            /*setup fub*/
            this->fbInfo.enable = 1;
            this->fbInfo.pDevice = (UDINT)inst->szDevice;
            this->fbInfo.pName = (UDINT)inst->szFile;
            this->fbInfo.pInfo = &this->Info;

            //call fub
            FileInfo(&this->fbInfo);

            //fub is done..
            if(this->fbInfo.status != ERR_FUB_BUSY)
            
                //file exists -> open it and append code
                if(this->fbInfo.status == ERR_OK)
                
                    //start writing to the end of the file
                    this->Offset = this->Info.size;

                    //open existing file
                    this->Step = stTEACH_OPEN;
                
                //file does not exist -> create it and insert code
                else if(this->fbInfo.status == fiERR_FILE_NOT_FOUND)
                
                    //start writing at the beginning of the file
                    this->Offset = this->Info.size;

                    //crete new file
                    this->Step = stTEACH_CREATE;
                
                //error
                else
                
                    //set error status and goto error state
                    inst->Status = this->fbInfo.status;
                    this->Step = stTEACH_ERROR;
                

                //disable fub
                this->fbInfo.enable = 0;            
                FileInfo(&this->fbInfo);
            

            break;

        case stTEACH_CREATE:

            /*setup fub*/
            this->fbCreate.enable = 1;
            this->fbCreate.pDevice = (UDINT)inst->szDevice;
            this->fbCreate.pFile = (UDINT)inst->szFile;

            //call fub
            FileCreate(&this->fbCreate);

            //fub is done..
            if(this->fbCreate.status != ERR_FUB_BUSY)
            
                //success
                if(this->fbCreate.status == ERR_OK)
                
                    this->Ident = this->fbCreate.ident;

                    //open existing file
                    this->Step = stTEACH_WRITE;
                           
                //error
                else
                
                    //set error status and goto error state
                    inst->Status = this->fbCreate.status;
                    this->Step = stTEACH_ERROR;
                

                //disable fub
                this->fbCreate.enable = 0;          
                FileCreate(&this->fbCreate);
            

            break;

        case stTEACH_OPEN:

            /*setup fub*/
            this->fbOpen.enable = 1;
            this->fbOpen.pDevice = (UDINT)inst->szDevice;
            this->fbOpen.pFile = (UDINT)inst->szFile;
            this->fbOpen.mode = fiREAD_WRITE;

            //call fub
            FileOpen(&this->fbOpen);

            //fub is done..
            if(this->fbOpen.status != ERR_FUB_BUSY)
            
                //success
                if(this->fbOpen.status == ERR_OK)
                
                    this->Ident = this->fbOpen.ident;

                    //open existing file
                    this->Step = stTEACH_WRITE;
                           
                //error
                else
                
                    //set error status and goto error state
                    inst->Status = this->fbOpen.status;
                    this->Step = stTEACH_ERROR;
                

                //disable fub
                this->fbOpen.enable = 0;            
                FileOpen(&this->fbOpen);
            
            break;

        case stTEACH_WRITE:

            /*setup fub*/
            this->fbWrite.enable = 1;
            this->fbWrite.ident = this->Ident;
            this->fbWrite.offset = this->Offset;
            this->fbWrite.pSrc = this->szLine;
            this->fbWrite.len = this->Lenght;

            //call fub
            FileWrite(&this->fbWrite);

            //fub is done..
            if(this->fbWrite.status != ERR_FUB_BUSY)
            
                //success
                if(this->fbWrite.status == ERR_OK)
                
                    this->Ident = this->fbWrite.ident;

                    //Write existing file
                    this->Step = stTEACH_CLOSE;
                           
                    //error
                else
                
                    //set error status and goto error state
                    inst->Status = this->fbWrite.status;
                    this->Step = stTEACH_ERROR;
                

                //disable fub
                this->fbWrite.enable = 0;           
                FileWrite(&this->fbWrite);
            
            break;

但是，这也应该与 FileOpen FUB 的 filelen 输出一起使用 - 就像您所做的那样。我建议您在写入之前设置一个刹车点，并检查 FUB 上是否正确设置了偏移量。

我还建议您在完成后调用每个 FUB，再次使用 enable:=0（就像我在示例中所做的那样），即禁用它。一些 FUB 仅在 enable、execute、start 等输入命令的上升沿更新其输入参数。

我希望这会有所帮助！