That means labview (VISA Read) accepts asciii as a default data types.
It does not. It reads bytes. You can interpret the bytes any way you need to based on the instrument you are communicating with. It uses a string since that's the most efficient way to store a sequence of bytes whose length you do not know ahead of time.
Is it like that, if I change the input data types to Int, Float, Signed Int then labview (VISA Read) gives me different
I do not understand what this means, since I do not know what you are referring to. Change the input data types of what?
Also, please do not use text-speak like "m" and "n" to replace "am" and "and". This is a professional forum, not Facebook.
NO! That is still not correct. One byte reads as one byte. Period. End of story. Stop thinking about characters, and think about bytes only. The character "A" is represented in ASCII as the decimal 65. That's one byte. Thus, if you read one byte from VISA Read and its value is 65, then you could intrepret it as the character "A". Or, it could also simply mean a byte value of 65, which could correspond to a specific command code (i.e., command code of 64 = read voltage; command code of 65 = read current). It all depends on the device you are talking to.