Step7 Indirect Addressing DBX

Peter Quiring · Sep 27, 2016

If I have a DB like this:
DB180:
field1 ARRAY[1..96] BYTE
field2 ARRAY[1..96] BOOL

How would I indirectly address a bit in field2?
Would this work in my function?

IN : #offset : DWORD = bit offset into field2

OPN DB180
L P#96.0
L #offset
+D
T #offset
A #some_condition
= DBX[#offset]

Would that work?

Iner · Sep 27, 2016

You need to convert your DWORD offset into pointer format using SLD 3 instruction

L D[AR2P#0.0] · Sep 27, 2016

Yes, just be aware that as your arrays are not zero based, the offset will refer to array element offset+1

e.g.

SHKODRAN · Sep 27, 2016

Using registry:
OFFSET : DWORD;
CONDITION: BOOL;

Code:

      LAR1  #OFFSET
      +AR1  P#96.0
      OPN   DB   180
      A     #CONDITION
      =     DBX [AR1,P#0.0]

Peter Quiring · Sep 27, 2016

thanks

thanks, I will try at lunch tomorrow and hopefully do not crash cpu

Peter Quiring · Sep 27, 2016

Iner said:
You need to convert your DWORD offset into pointer format using SLD 3 instruction

The "L P#96.0" is already shifted 3 bits (the P indicates it's a pointer). So adding the #offset should give the correct "bit" offset.
field1 was BYTEs
field2 was BITs

Step7 Indirect Addressing DBX

Peter Quiring

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Iner

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L D[AR2P#0.0]

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SHKODRAN

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Peter Quiring

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