indirect pointing at the UDT

Hi,
if I want to point indirect to a UDT which is in an array how can I do it?
I can do it not indirectly:
I have declaration in DB10: Objekt Array[1..100] of UDT1, so DB10.Objekt[1] points at the first element of my array.
But what if I want to point at this element indirect, and then to give the begining address to the any pointer?

Regards.

Martin

First I assume that you use S7.
It's not possible to directly access indirectly given data in DB.
You have to open the DB first and then you can access indirectly data in it.
However you can create FC/FB with an input of type POINTER, and then assign "DB10.Objekt[1]" to this input.

Yes, its true, but I don't want to give the name "DB10.Objekt[1]" to FC but only an adress of this object. Is it possible?

I'm not sure if I understand you.
What should be possible ?

Martin, do you mean you want to pass an any pointer as a parameter but that instead of putting "DB10.Objekt[1]" as the parameter, you want to contruct the any pointer yourself and pass this to the function ?

If so, create a temporary variable of type any and then proceed to populate the any pointer with the length,type, DB and area pointer yourself. You will still have to reference "DB10.Objekt[1]" somewhere in order to determine the any pointer parameters.

On a more general note, could you explain why you need to do this - it would give a more information for suggesting a solution.

Hi,
I have more then one DB with objects of UDT type. The easiest way would be to do DB[nr].Objekt[1] and then to increment nr to reach objects in a next DB, but it is imopssible. I mean all the DBs have Objekt[1] under the address 0.0, but the array Objekt[1..100] in each DB consist of different UDTs. I mean in DB1 Objekt[1..100] is of type UDT1, in DB2 Objekt[1..100] is of type UDT2 and so on. So, I thought about indirect adressing.
I need this to calculate the lenght of UDTs.
Other thing is that I need to have DBs of UDT type, without array of UDTs, and I need also to know the lenght of this UDT. That is why I try to give the adress of UDT to ANY pointer.

regards

Martin

OK. I see.
It's not possible to get size of a UDT at runtime directly (or I don't know such a solution).
One workaround could be as follows:
- open DB
- get its lenght (with "L DBLG" instruction)
- divide it by size of the array (but this must be known in advance)

Martin, have a look at this previous thread, it may give you some ideas



http://www.plctalk.net/qanda/showthread.php?t=8850&highlight=size+array

I read the thread that you showed me, but it's not exactly what I need. There is only one DB, you and S7Guy if you want to calculate the lenght of a UDT give always the instruction by the name of the DB and the name of an array( DBNAME.ARRAYNAME[1]). The problem is that I don't want do give a name of a DB. The best way would be to do something like this: DB[db_nr].array_of_udts[udt_nr]. Thus I could easily move from objects of one DB to objects of an another DB, only by changing a db_nr and udt_nr.
And of cours I don't have SCL:-((