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How to program x ^ y in Structured Text [message #1742792]

Wed, 07 September 2016 15:38

Wolfgang Trischnigg

Messages: 45
Registered: April 2016

Member

Dear all,

can anyboday help me please?
I'm trying to do a operatiobn like x^y.

How can I handle that in ST?

I've tried EXPT(x, y), but without of success.

Thank you, Wolfgang

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Re: How to program x ^ y in Structured Text [message #1742826 is a reply to message #1742792]

Wed, 07 September 2016 22:59

Alois Zoitl

Messages: 1582
Registered: January 2014

Senior Member

Hi,

I would have suggested to use EXPT. Therfore I'm curiose what is the problem with it?

Alois

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Re: How to program x ^ y in Structured Text [message #1743587 is a reply to message #1742826]

Fri, 16 September 2016 15:23

Wolfgang Trischnigg

Messages: 45
Registered: April 2016

Member

When I export EXPT(x,y) I get Errors when compiling.
When I remove EXPT, eb´verything is fine - seems cpp does not know "EXPT"?

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Re: How to program x ^ y in Structured Text [message #1743588 is a reply to message #1743587]

Fri, 16 September 2016 15:27

Wolfgang Trischnigg

Messages: 45
Registered: April 2016

Member

It only works when I write pow(x,y) in cpp.

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Re: How to program x ^ y in Structured Text [message #1743632 is a reply to message #1743588]

Sat, 17 September 2016 11:55

Alois Zoitl

Messages: 1582
Registered: January 2014

Senior Member

Hi,

I just wrote a simple test FB where I used two input ars of type lreal and one outputvar of type lreal and EXPT the two inputs on the output and it worked without issues. Would you have an algorithm or an EXPT line for me that reproduces the issue. Maybe there is a bug in the code generator.

Thanks,
Alois

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Re: How to program x ^ y in Structured Text [message #1743704 is a reply to message #1743632]

Mon, 19 September 2016 06:58

Wolfgang Trischnigg

Messages: 45
Registered: April 2016

Member

Hi Alois,
in my case the FB has several inputs, which were used to calculate a formula.
Inputs:
A, B, C - type Float
Output:
D - type Float
This should happen for example:
EXPT( ( (A+B) * C ), 0.8 ) = D

Visual C++ says:
error C2825: "T": Muss eine Klasse oder ein Namespace sein, wenn gefolgt von "::".
4> ..\..\..\src\modules\test.cpp(44): Siehe Verweis auf die Instanziierung der gerade kompilierten Funktions-template "const T EXPT<double>(const T &,const T &)".
4> with
4> [
4> T=double
4> ]
4>\desktop\forte\forte_1.8_m1\src\core\iec61131_functions.h(535): error C2039: 'TValueType': Ist kein Element von '`global namespace''
4>\desktop\forte\forte_1.8_m1\src\core\iec61131_functions.h(535): error C2061: Syntaxfehler: Bezeichner 'TValueType'

[Updated on: Mon, 19 September 2016 07:13]

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Re: How to program x ^ y in Structured Text [message #1743885 is a reply to message #1743704]

Tue, 20 September 2016 12:07

Alois Zoitl

Messages: 1582
Registered: January 2014

Senior Member

Hi,

thanks for this info this helped me to sort the problem out. As this affects several of the functions I created a bug report for it [1]. A first fix for the EXPT is already committed to FORTE's git repository. So if you clone it and switch to the 1.8.x branch your FB should now compile.

BR,
Alois

[1] https://bugs.eclipse.org/bugs/show_bug.cgi?id=501817

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