Why does fclose() / instrreset cause MATLAB to hang when closing a VISA-USB object?

Question

Liz Dreyer 2014-7-28

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/143615-why-does-fclose-instrreset-cause-matlab-to-hang-when-closing-a-visa-usb-object

回答： Walter Roberson 2016-11-21

I am controlling both a Thorlabs optic power meter over visa-usb and a Newport motor controller over serial.

USB:

pmAddress = 'USB0::0x1313::0x8078::P0008339::INSTR';
pm100d = visa('ni',pmAddress);
fopen(pm100d);
... communicate with instrument ...
fclose(pm100d);
delete(pm100d);
clear pm100d;
instrreset;

SERIAL:

gSmc = serial('com3','BaudRate',9600,'DataBits',8,'Parity','None','Terminator','LF');
fopen(gSmc);
... send commands ... 
fclose(gSmc);
delete(gSmc);
clear gSmc;
instrreset;

In the serial case, everything works as intended. In the USB case, fclose() causes MATLAB to hang. I can't ctrl-c the process, and I can't do anything to resolve the problem except forcing MATLAB to quit.

I tried using instrreset instead and the same problem happens for the VISA-USB object.

What could be causing this?

Thanks for your help.