Late

Hi Rajasekhar,

POINTER:
References the address of a variable.

A pointer contains an address instead of a value. When you supply a value to a formal parameter of the parameter type POINTER, you specify an address as the actual parameter. In STEP 7, you can specify a pointer in the pointer format or simply as an address (for example, M 50.0). Example of a pointer format for addressing the data beginning at M 50.0: P#M50.0

But you could give also no type of variable:

L	P#8.7	Load the value of the pointer into accumulator 1.
T	MD2	Transfer the pointer to MD2.
A	I [MD2]	Query the signal state at input bit I 8.7 and
=	Q [MD2]	assign the signal state to output bit Q 8.7.

Or with a type of variable over the address registers:

L	P# I8.7	Load the value of the pointer and the area identification in accumulator 1.
LAR1		Load memory area I and the address 8.7 into AR1.
L	P# Q8.7	Load the value of the pointer and the area identification in accumulator 1.
LAR2		Load memory area Q and the address 8.7 into AR2.
A	[AR1, P#0.0]	Query the signal state at input bit I 8.7 and
=	[AR2, P#1.1]	assign the signal state to output bit Q 10.0.

So this Pointer will give you the opportunity to use a variable Operator in the mentioned commands so that you can work with variable units.

Hi,

I am new in pointers.

I cannot undestand the use of the pointer, could you explain me the above?

After use P#I8.7 and P#Q8.7, you finaly chek the signal at input I8.7 and then assign Q10.0.

What is the differnce if i just write :

A I8.7

=Q10.0

What's the advantage of using pointers?

Thanks,

Michalis.

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Split from Format of the parameter Type POINTER.

Hello,

there are also a lot of FAQs for indirect addressing and programming with pointers in the internet. See also the overview FAQ first:

Which FAQs, application examples and manual information are available for indirect addressing in STEP 7 V5.x?
https://support.industry.siemens.com/cs/ww/en/view/24521797

With best regards
Cicero