Empty available serial ports list for visa interfacing

Hello !

I am trying to control an Agilent Power supply via Matlab but my computer do not recognize it. I use visa to open it :

obj = visa('ni', 'GPIB1::2::INSTR');
fopen(obj)

The error then is : Invalid RSRCNAME specified. Type 'instrhelp visa' for more information.

In fact, the problem seems to be that no serial port is available. In particular, the command

instrhwinfo('visa', 'ni');

returns :

AdaptorDllName: 'C:\Program Files\MATLAB\R2021b\toolbox\instrument\instrumentadaptors\win64\mwnivisa.dll'
AdaptorDllVersion: 'Version 4.5'
AdaptorName: 'NI'
AvailableChassis: []
AvailableSerialPorts: ''
InstalledBoardIds: []
ObjectConstructorName: []
SerialPorts: ''
VendorDllName: 'nivisa64.dll'
VendorDriverDescription: 'National Instruments VISA Driver'
VendorDriverVersion: 20

So the AvailableSerialPorts is empty... I think this is the problem but cannot see how to solve it. The command

instrhwinfo('Serial')

returns something similar.

Interestingly, the same piece of code works with another computer (in Matlab R2019b)... Do you have some tips ? Thanks !

V.M.