indirect addressing

martin3885

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• Aug 25, 2005

• #1

Hi everyone!
Is it possible to call FB which number will be given by indirect addressing? I mean I need to call the FB No. where No. is the parameter which stores a number of an FB which I want to call. In other words I don't want to call for example a FB1 but FB No. Sometimes No.=1, sometimes No.=10... The same thing I need to do by opening a data block.

Best regards
Martin

 

martin3885

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• Aug 25, 2005

• #2

Hi that's me again.

I need to do this in S7 in STL.

Regards

 

RMA

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• Aug 25, 2005

• #3

This recent Thread applies equally to accessing FBs indirectly.

 

martin3885

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• Aug 25, 2005

• #4

Thanks RMA! I have read this thread, but there is nothing about FBs. Do you know how can I do it?

Regards

Martin

 

SimonGoldsworthy

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• Aug 25, 2005

• #5

To call FB's and FC's indirectly, you cannot pass parameters in the call and you use the following method:

L 1
T MW 100
UC FB [MW 100]

If you want to use parameters, declare them in the interface and load them manually before you call the FB, then read them manually after calling the FB. You must set AR2 and the instance DB yourself. I think there is another thread that gives a more specific example, I'll have a look for it.

 

martin3885

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• Aug 25, 2005

• #6

Many thanks SimonGoldworthy! I will try it out, with DB and parameters I must think a little bit how to do this.

 

SimonGoldsworthy

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• Aug 25, 2005

• #7

Have a look at this post for an example of calling an FB with no parameters but setting up the parameters beforehand. It should give you an insight into the work required to do this indirectly! (Cut/paste the code into a source code folder and compile it and then view in the editor)


http://www.plctalk.net/qanda/showthread.php?p=95075&highlight=ar2#post95075

 

Last edited: Aug 25, 2005

RMA

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• Aug 25, 2005

• #8

Something seems to have gone wrong with your link Simon - that link leads to your personal profile!

 

martin3885

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• Aug 25, 2005

• #9

SimonGoldworthy, as RMS has already mentioned this link doesn't work properly. I have found following:
http://www.plctalk.net/qanda/showthread.php?t=15118&highlight=calling+FB
But I still can't work out how should the code of my program look out. I would be thankful if you could post the link once again. Thanks!

 

RMA

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• Aug 25, 2005

• #10

Simon's already corrected the link, it's working now.

 

martin3885

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• Aug 25, 2005

• #11

Thanks RMA.

One more question, it should be easy(but not for me ). How can I print my program to the txt or doc file? I do it with print instruction but I can only print to the pdf file.

 

SimonGoldsworthy

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• Aug 25, 2005

• #12

From the block editor, options/customize/sources tick the box "Generate Source Automatically". Every time you save a block, the source code will be produced in your source code folder. You can then export the source code or open the source code and cut/paste the text. Hope this is what you are trying to do.

 

martin3885

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• Aug 30, 2005

• #13

Hi,
I was looking at the Simons' programm http://www.plctalk.net/qanda/showthread.php?p=95075&highlight=ar2#post95075,
and I don't know one thing.
In the network 3 we do following thing:

TAR2 #dwar2Store //save AR2 as it points to this FBs instance data, don't refer to static data in this network !
L P##fbQ1 //point to start of data
+AR2 //for first instance
L P##fbQ2 //point to next instance

I mean we do +AR2. It means that we add Akku1 to the AR2, but how do we know what is in AR2 on the begining?
Why don't we use here an instruction TAR2?

 

SimonGoldsworthy

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• Aug 30, 2005

• #14

At the start of the call to FB3, AR2 points to the static data area associated with this instance of FB3 and will depend on where FB3 has been called from (as well as how many other instances have been declared). Note also that the only requirement for the static data area is that FBQ1...FBQ5 follow on from each other, if more static data was to be declared before them, I need to point to the start of FBQ1's static data area and add this offset on to AR2 to keep the code generalised.

Try declaring FB3 as several instances in another FB, then call the second instance only. If you monitor AR2 you will see it will point part way through the instance DB and not the start of the DB.

 

martin3885

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• Aug 30, 2005

• #15

"Try declaring FB3 as several instances in another FB, then call the second instance only. If you monitor AR2 you will see it will point part way through the instance DB and not the start of the DB."

You mean to make some static variables of type FB3?
For example: Object1 type:FB3
Object2 type:FB3
.
.
.