Hi.

You already have the answer you asked for.
A "hair splitting" caution though....
Be careful what is meant by 'first bit'.

An added notes..
Visually demo: slicing vs overlay on bit level

fahad992

Thank for your answer,  but I did not understand what you are meaning by hair splitting , take in considration I am beginner level.

Hi.      Sorry about that...

"hair splitting" is not meant by me as a technical term.
It is meant as a phrase belonging to the English language.
..and I mean the formal language - not the rude street language.

"hair splitting" is about arguing on a small detail that has no real significance.
A formal definition could be found...  [LINK]

Greetings.
w

Maybe it is good if I explain a little detail.

Let us assume there is a tag created..
%MW10  :  "value"   as UINT

In the Siemens S7 range we work with the CPUs
as if they are 8 bit processors.
In this case "value" is constructed from all bits from %M10.0 to %M11.7.
Keep in mind that %M10.0 to %M10.7 makes %MB10
and %M11.0 to %M11.7 makes %MB11.

If we use the bit "value".%x0 in symbolic representation,
it is the same as working absolute addressing with %M11.0.
Yes! %M11.0   not %M10.0.

It is also the same as if we MOVE  1   into  "value".

PLEASE go ahead and make a small program & do a simulation to see these things for yourself.


This is the potential issue I am trying to highlight to you.
The chance is however very remote that this is actually a problem.

Does this clear up some questions?
What are your thoughts?
w

fahad992

Thank you William, now I got better view about this subject, 

so to set a bit in a word or else,,is by move from another operand value to this bit,, by the way I don't want to effect on other bits ..

The first answer you got will do what you asked.