how to communicate with an instrument with GPIB

[Nahed]

Hi 

[GerdW]

Hi Nahed,

you forgot the Devices tree.

And you seem to use a 64bit-version of LabVIEW: is there a reason to do so?

I would use a 32bit version!

(There might be a bitness problem, please read the compatibility entries for both VISA and GPIB drivers.)

[Nahed]

Hi 

look what I mean .the PC dectect the instrument but in labview no

[rolfk]

Do you use an NI or Agilent/Keysight GPIB interface? That is important to know!

[Nahed]

I use an NI interface

[NIquist]

I have found that other manufacturer's VISA drivers (Agilent, Tektronix) will tend to fight with NI's version so you might want to make sure you install the NI drivers AFTER any other packages.  I remember constantly having to re-install NI-VISA after my fellow employees installed a Tektronix tool to print out o-scope data.  Turns out the installer replaced visa32.dll with its own tiny version which broke all the NI drivers.

[Nahed]

Thanks for your help 
I will do all you say and I will tell you all news