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Write real variables from Labview 8.2 to Twincat embeded application

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I am currently using Labview to write and read some variables defined through an embedded Twincat application.

I have defined the following variables in Twincat :


    Lab_lecture_real AT %MW100 : REAL;
    Lab_ecriture_real AT %MW102 : REAL;

    Lab_lecture_bool AT %MB1 : BOOL;
    Lab_ecriture_bool AT %MB2 : BOOL;


Based on the VI given by Beckhoff for Twincat ADS/OCX (😃 , I succeed to read the variables "Lab_ecriture_real" and "Lab_ecriture_bool" and write through "Lab_lecture_bool".

Nevertheless, i failed to write in "Lab_lecture_real", which is a real.


I have enclosed my VI, everything seems to be correctly connected. Though, I don't understand why it works for a Boolean variable rather than a real one. Maybe the method used for writing a real is different from Boolean.

Could you highlight me on this subject, please?




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Accepted by topic author Steffff

Why are you setting the length for the REAL number as 8 in the VI?

Is it in the documentation for the OCX somewhere else?

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I have just tried with the length for the real as 4 and it seems to work.


Thanks a lot for your answer !

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Since a Boolean is a 1, and a Real is a 4, it would indicate that the length is in terms of bytes.



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