https://forge.codesys.com/forge/talk/CODESYS-V2/thread/8635bcf179/2020-02-27T22:59:35.375000ZRecent posts to Struct alignment with FB parameters in external library2020-02-27T22:59:35.375000Z2020-02-27T22:59:35.375000ZFoxhttps://forge.codesys.com/u/fox/https://forge.codesys.com488a1f8bd116fcf353ee620fabca96d172892b76

<div class="markdown_content"><blockquote> <p><strong>shooter hat geschrieben:</strong><br/> make it a little bigger and you will see more discrepancies.<br/> Surely I will if struct alignment settings are diffenent <br/> <strong>shooter hat geschrieben:</strong><br/> yes it does because there is a header on a structure.<br/> You mean there is no way to solve that, for example with some pragmas?<br/> I've tried to set 1-byte alignment option within VC++b(with "" command), but it doesn't work (I'm still trying to find out the reason).<br/> I'm confused </p> </blockquote></div>

2020-02-27T22:59:33.624000Z2020-02-27T22:59:33.624000Zshooterhttps://forge.codesys.com/u/shooter/https://forge.codesys.com504870d7c3997d25ea6ab7a8e3d076f5c55195d8

<div class="markdown_content"><p>yes it does because there is a header on a structure.<br/> make it a little bigger and you will see more discrepancies.</p></div>

2020-02-27T22:59:29.116000Z2020-02-27T22:59:29.116000ZFoxhttps://forge.codesys.com/u/fox/https://forge.codesys.com84c7bd3fe643b04067a7f09fbd5da85a709f63a2

<div class="markdown_content"><p>Hi all.<br/> I'm developing my own external library (with Visual C++ 6.0) and lately encountered with interesting bug that I fixed in abnormal (by my consideration) way. I would like to get rid of that abnormal fixing. Currently I have no real PLC and execute my experiments with "SP PLCWinNT v2.4" simulator.<br/> There is an example Function Block declared in my lib-project:</p> <p>There is a h-file automatically generated by CoDeSys:</p> <p>Please notice on F_Reserv parameter. I don't need it and it is my way of fixing the following problem: when my parameter list is declared without F_Reserv - the structure alignment in the compiled C-code and in the PLC memory is different. The <span style="color: #0040FF;">sizeof</span>(LIB_FUNCtyp) is equal to 24 bytes in compiled C-code (that is perfectly correct due to 4-byte struct alignment set in project's Options) , but it seems that it equals to 21 bytes in PLC memory, cause debug process shows complete mess with values. <br/> So when I declare <strong>F_Reserv : ARRAY<span><span>[1..3]</span></span> OF BOOL</strong> in CoDeSys (forcing appropriate struct alignment) and comment (disable) the corresponding line <strong>BOOL F_RESERV<span><span>[3]</span></span></strong> in C-code - my Function Block performs as designed.<br/> How should I get rid of that unwanted declaration? There are no any alignment parameters in Target settings of Soft PLC and it seems that it uses 1-byte alignment option. </p> <p>I feel there should be a simpler way to solve that.<br/> Thanks.</p> <p><img alt="IMG: Bild" rel="nofollow" src="http://i.snag.gy/BLPNT.jpg"/></p> <p><img alt="IMG: Bild" rel="nofollow" src="http://i.snag.gy/wKfML.jpg"/></p></div>