S7-300 trouble direct addressing within FB STL

minerman · Apr 20, 2013

I have an FB that I'm trying to write to a data array inside of it's local DB.

I am trying to:
T LW 2272

So 2272 / 8 should give me local address 284.0, right?

When I attempt to download the program it says the address is out of range.

I'm new at this, maybe I don't understand how the local addressing works?

KalleOlsen · Apr 20, 2013

The 'local DB' is the instance DB and can be accessed with DIX/DIB/DIW/DID and in your case DIW 284 is relevant.

The LW accesses the Temporary memory stack, and byte 2272 is probably out of range for your CPU type.

Kalle

PS! Post your code, it might be more uncovered pitfalls.

minerman · Apr 20, 2013

Here's the STL code that I'm having trouble with...

Other than #temp_pointer, the other variables are loaded elsewhere...

Code:

A #S_Timer_Done
JC N33A
JU N33B
 
//Load S Count into Array if timer is done
 
N33A: L #S_Count_Array_Pos
L 284
+I
T #Temp_Pointer
L #S_Counter
T DIW [#Temp_Pointer]
 
//Clear S Counter
 
L 0
T #S_Counter
 
N33B: NOP 0

My data is not making it into the array. I am positive the array starts at 284.0 I can do a DIW 284 in a separate rung and it makes it there. I have verified that I do get the S_Timer_Done bit true, so that is not the issue.

L D[AR2P#0.0] · Apr 20, 2013

Pointers resolve down to the bit address so if you want to access a byte then you must multiply by 8 or SLD 3, however, you have an array of words so a SLD 4 is required. I've added the offset by loading the pointer format directly.

Code:

A #S_Timer_Done
JC N33A
JU N33B   
//Load S Count into Array if timer is done
N33A: L #S_Count_Array_Pos
SLD 4 //index into array of words
L P#284.0 //offset to start of array
+D
T #Temp_Pointer 
L #S_Counter
T DIW [#Temp_Pointer]   //Clear S Counter   
L 0 
T #S_Counter   
N33B: NOP 0

L D[AR2P#0.0] · Apr 20, 2013

Also note that if you use this FB as a multiple instance your DIW addressing will fail.

minerman · Apr 20, 2013

L D[AR2 said:
Also note that if you use this FB as a multiple instance your DIW addressing will fail.

Yeah, I actually am using it in multiple instances, each with a separate data block, of course. It seems like Kalle was thinking the DIW would be referenced locally, so why would it fail?

minerman · Apr 20, 2013

You must be correct about the multiple FBs, because its not working. How do I make it work?

It's just constantly loading into the first register. I don't understand.

I just attempted taking the offset out. No luck. Now, I'm not recording at all, despite the fact that I am storing 284 in the S_Count_Array_Pos number now.

L D[AR2P#0.0] · Apr 20, 2013

If you are calling each FB with it's own instance DB, this is not multiple instance so your code will be ok under these circumstances.
(multiple instance refers to when you embed FB's into the stat area of another FB, you can then use one instance DB and it will contain all the instance data of all the FBs)

L D[AR2P#0.0] · Apr 20, 2013

Create a library, insert an S7 program into it, copy your blocks to the library, archive it and then post as an attachment.

L D[AR2P#0.0] · Apr 20, 2013

Here's some test code that works - I'm incrementing the array index after each write and the data I'm writing is the array index + 100:

L D[AR2P#0.0] · Apr 20, 2013

DB data:

S7-300 trouble direct addressing within FB STL

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