Hi, I'd like to use a variable to address and energize a specific bit in an INT Tag. For example, let's say I have a INT tag named "TBD_INT", and I'd like to energize the second bit of this integer so it has a value of 2. Can I use variable addressing to do that? If so, what is the syntax I should use?

I tried #TBD_INT.%X[variable] and #TBD_INT.%X(variable). None of them worked...

I am using TIA Portal v13 to program a S7-1500. Thanks for your help.

Hello jluo,

use two INT tags, "TBD_INT" and "BITSET" (with value 2 in your example).

Use an AND function(WORD AND) with both tags on input and give result to  "TBD_INT".

Thats it

regards

FUNCTION "ChangeBit" : Void
{ S7_Optimized_Access := 'TRUE' }
VERSION : 0.1
   VAR_INPUT
      N : UInt;   // Position of bit to change
      STATE : Bool;   // Change the state of the bit
   END_VAR

   VAR_IN_OUT
      Q : UInt;   // Field value that requires the change
   END_VAR

   VAR_TEMP
      S : Word;   // Temporary result
   END_VAR


BEGIN
    #S := UINT_TO_WORD( ROR_UINT(IN := #Q, N := #N) );
    #S.%X0 := #STATE;
    #Q := WORD_TO_UINT( ROL_WORD(IN := #S, N := #N) );
END_FUNCTION

The challenge is when you have to conform with a certain data type.
Some tricks used in STEP7 V5.x may not work so well in TIA
Note that you can do a conversion INT <-> UINT using the CONV instruction.

Helpful?
w

What about upping the game a BIT?
Maybe take a BYTE out of the idea in the image.

Take care that this one might be a little tricky to do. It uses the AT overlay method and is employed in an FB code block with optimised data structure. Doing the AT overlay in this type FB is only possible in TIA13.. notice the setting in the RETAIN column.

w

Do you mean Slice Access with Variables [n] for INT type:

ProcessInterlock.%X[n] for bit n?

I want to know too how to do it in simple step in LAD.

VAuchtung

Do you mean Slice Access with Variables [n] for INT type:

ProcessInterlock.%X[n] for bit n?

I want to know too how to do it in simple step in LAD.

What you ask there, cannot be done.
The closest we have is to get the bits in an array. Luckily we can use the AT overlay method for that. My last example uses that method. Please have a look.

William B.

..or alternatively have a look at an official FAQ [LINK]

 All this FAQ shows is how to do simple things in a complicated (and time consuming) way.

Every PLC has a native support for bit operations as this is its primal objective. And the code presented shows how to do bit operations on a machine without bit operations. Guy who wants to learn PLCs' programming will get his mind campletely messed up...

jacek d

 ...Guy who wants to learn PLCs' programming will get his mind campletely messed up...

(smile) we are in complete agreement - but that is the "official" examples.