Allen Bradley/Siemens s7

Hi everyone

I´ve been converting an Allen Bradley plc program written in Rslogix to a Siemens plc program written in Simatic Step7.

Allen Bradley :

An adres is for example given by N7:0
Its of the type word and here we can store a value

Now say we have 2 adresses
N7:0
N7:1

The values in these adresses varie constantly so we can make it as a pointer and use it as the following
N[N7:0]:[N7:1]
So the new adres varies in function of the value of the previous adresses.


Siemens :

I know that the adress can be given as follows

For example we create a data block, and within we define some variables(let´s say of the type WORD). These variables are given adresses.

For example

In DB1 we have a word DBW0

When we call upon the adress in OB1 we type the following

DB1.DBW0
as such we use the value that is given to this variable.

Say once again that we have 2 variables

DB1.DBW0
DB1.DBW2

My question is , how can we now do the same as above with allen bradley
That is creating an adress that varies because of the values within DB1.DBW0 and DB1.DBW2

In other hand, I know what to do but I don´t know the syntax. The help of step7 didn´t help me at all.

Can someone help me?
Thx

S7 developer, goto Help-> Help on STL->find->indirect->(select:
1'st 'indirect'->Select: Memory Indirect Addressing
And there it is.

Hello;
An important detail for memory indirect addressing in Syep 7: you can only implement it with STL propgramming, no LAD or FDB blocks allowed.
It might look more difficult at first, but the learning curve is not steep.
Hope this helps,
Daniel Chartier

thx guys

thx guys,; I figured it out after I posted the question. You were both right. I found something about it in the help of s7.
I just programmed a function witch I can use as a block in LAD. The function itself is written in STL. It wasn't that difficult but I have to say that programming with allen bradley is much more user friendly.

Thx for your replies