How to initialize arrays of function blocks that need FB_Init to work

2020-08-21T14:07:10.799000Z

would also work for you! Why it should not? what's the problem?
workaround is not clean code. try directly ;)

How to initialize arrays of function blocks that need FB_Init to work

2020-04-24T22:17:05.613000Z

Hello,
I was interested. Unfortunately, your yannickasselin1 method didn't work for me.
I came up with a workaround - instead of FB_INIT I created a normal method: INIT (with the same implementation as FB_INIT). But since it's not called before running, I call them separately inside the FB_INIT method in another FB. For Example:

MyObject
METHOD init 
VAR_IN_OUT
    ptrCF : ptrCF;
END_VAR

HelpObject
METHOD FB_INIT
FOR i := 0 TO 3 DO
    MyObjectArray[i].init(ptrCF[i]);
END_FOR

GLOBAL_VAR
     MyObjectArray: ARRAY[0..3] OF MyObject;
     ptrCF : ARRAY[0..3] OF ptrCF;
END_VAR

How to initialize arrays of function blocks that need FB_Init to work

2020-02-27T13:59:49.515000Z

@Joan M

If anyone still looking for a way to achieve initialization of an array of objects through FB_Init, here's the syntax that worked for me:

MyObjectArray: ARRAY[0..3] OF MyObject[(1), (2), (3), (4)];

It is almost the same as Joan M tried in his exemple except that I have removed the " := " sign.

Enjoy.

How to initialize arrays of function blocks that need FB_Init to work

2020-02-27T13:59:49.247000Z

Originally created by: Catharine Coombs

https://explainjava.com/ They are written simple here, so it went out clear to me as to guys with no experience. But now I know for sure that CDS is not the very thing you need to try when you just have started practicing

How to initialize arrays of function blocks that need FB_Init to work

2020-02-27T13:59:48.406000Z

Originally created by: scott_cunningham

I don't think your array initialization will ever work without a change from 3s. If you play around a bit, one of the precompile errors will be .

To clarify... when you try to initialize your array, you are defining what your objects should literally , not how they should initialize. Take for example:

MyArray : ARRAY[0..1] OF INT := [1, 2];

You are telling the compiler you want your integers to integers 1 and then 2.

If you do:

MyArray : ARRAY[0..1] OF MyObject := [1, 2];

You are telling the compiler that you want your MyObjects to integers 1 and then 2.

This is not the same as having your object instantiate with a value of 1 and then 2. I doubt CoDeSys can do what you are hoping for.

In fact, this works (unfortunately, the precompiler really wants me to use MyObject(0) - otherwise it complains I am not following the Fb_INIT):

VAR
   Obj1 : MyObject(1);
   Obj2 : MyObject(2);
   MyArray : ARRAY[0..1] OF MyObject(0) := [Obj1, Obj2];
END_VAR

But this means your objects have to be created first and then put into the array (not what you wanted).

If you are looking to simply have a unique ID with every instance, see this thread: l viewtopic.php?f=11&t=7348 l

How to initialize arrays of function blocks that need FB_Init to work

2020-02-27T13:59:48.127000Z

Dears.

From your post I will test to pass parameters to FB_Init when the fB is created via __new and it works doing:

tst:=__new(test_class(temp:=450));

(Being temp an input of FB_init),

After that I have test to do the same in arrays, but I only can pass the same parameter to all FB_inits of the array:

tst2:ARRAY[0..2] of test_class(temp:=450);
All tst2 elements are initialized with temp:=50.

But in array initialization you could initialize internal FB variables:

tst2:ARRAY[0..2] of test_class:=[(tt:=1),(tt:=2),(tt:=3)];

Being tt internal variables of the FB not input variables of FB_init. That variables are setted after FB_init, but before a function with {'attribute call_after_init'}.

You can use internal variables as constructor inputs and put the constructor code in a function with 'call_after_init' attribute.

How to initialize arrays of function blocks that need FB_Init to work

2020-02-27T13:59:47.758000Z

Joan if I understand correctly, perhaps you can do something like the following example. I haven't tried it so don't know if this approach works.

// *** FB Definition
FUNCTION_BLOCK MyObject
VAR
   Id         : INT;
END_VAR
// *** Init Method
METHOD FB_init : BOOL;
VAR_INPUT
   bInitRetains   : BOOL;
   bInCodyCode   : BOOL;
   List         : POINTER TO ARRAY [0..32767] of MyObject;
   First         : INT;
   Last         : INT;
END_VAR
VAR
   i         : INT;
END_VAR
FOR i:=First TO Last BY 1 DO      // Search the list for self
   IF List^[i]=THIS^ THEN
      ID := i;
      Exit;
   END_IF
END_FOR
// *** Usage
VAR
   ObjectArray   : ARRAY [1..4] of MyObject(List:=ADR(ObjectArray), First:=1, Last:=4);
END_VAR

How to initialize arrays of function blocks that need FB_Init to work

2020-02-27T13:59:47.461000Z

Hi again camferti...

This is possible using the new Object Oriented Programming paradigm Codesys V.3 offers.

FB_Init is not a "normal" function.
It is the constructor function and it is used specifically to initialize internal things of the newly created function block. (Somehow configure it).
this function is automatically called each time you instantiate the object that owns it (so each time you instantiate the fb that has it implemented).

https://infosys.beckhoff.com/content/1033/tc3_plc_intro/9007199390945931.html?id=8333023073559976250

As a good example, it works when used alone (first line) in the program:

MyObjectAlone : MyObject(1);

Here I'm not calling FB_Init at all, but it is automatically called and it receives 1 as the parameter ID.
But it is not working when used in an array as I can't parameterize the FB_Init function...

The reason of this to fail must be:

A) The syntax I'm using is wrong (which is what I believe).
B) The implementation of this feature is not done even the error message doesn't suggest this.

In the newly attached picture you can see the errors the compiler show.

Hope this clarifies a little bit more what happens here.

Thank you very much.

Again, happy new year.

How to initialize arrays of function blocks that need FB_Init to work

2020-02-27T13:59:46.650000Z

Joan Murt hat geschrieben:
Hello again,
Some extra explanations in the pictures comments.
You can see three different ways to instantiate the MyObject function block in MyProgram.
The first method of instantiation works well, but it forces me to create instances individually and I loose the possibility to put them inside an array. This is how I'm doing it right now.
The second method doesn't work for me as I do need the FB_Init call which is not called/parameterized.
The third one is what I'm interested in but doesn't work.
Thank you for your time.

Do you want to use a variable that you define within a function in the program?
it's not possible.
Why do you want to do that? I do not see the meaning. What are you trying to do?

In the first line you make a call to the function "myObject (1)" so it does not give error
In the second and third where you make the call to the function? You do not start the instance

happy New Year

How to initialize arrays of function blocks that need FB_Init to work

2020-02-27T13:59:46.354000Z

Hello again,

Some extra explanations in the pictures comments.

You can see three different ways to instantiate the MyObject function block in MyProgram.

The first method of instantiation works well, but it forces me to create instances individually and I loose the possibility to put them inside an array. This is how I'm doing it right now.

The second method doesn't work for me as I do need the FB_Init call which is not called/parameterized.

The third one is what I'm interested in but doesn't work.

Thank you for your time.

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