Instrument control toolbox, problem communicating with instrument

I am able to communicate with my instrument (Signal Recovery 7270 DSP Lock-in Amplifier) only 1 out of 2 times. The signal send from fprintf always get to the instrument, but I can read from it only 1 out of 2 time. I am sure the command send to the instrument is right. I am sure that the command get to the instrument because it has a communication monitor where I can read the commands that have been send to it and the answer it will send.

Here is my code:

vu = visa('NI', 'USB0::0x0A2D::0x001B::11117372::0::RAW');

>> fopen(vu)

>> fprintf(vu,'ID')

>> fscanf(vu)

Warning: Unsuccessful read: VISA: Unknown status value 0xBFFF0015

ans =

     ''

>> fprintf(vu,'ID')

>> fscanf(vu)

ans =

7270

>> fprintf(vu,'VER')

>> fscanf(vu)

Warning: Unsuccessful read: VISA: Unknown status value 0xBFFF0015

ans =

     ''

>> fprintf(vu,'VER')

>> fscanf(vu)

ans =

2.00

>> fclose(vu)

Answer 1

[Camil]

The fprintf and fscanf were not send correctly.

I have to use:

 fprintf(vu,'%s', 'MAG'); %Reads Magnitude in volts
 fscanf(vu, '%c\n');

And that way it works!

Hope it can help someone one day.

Answer 2

[Walter Roberson]

Looks like that is a timeout. See http://forums.ni.com/t5/Instrument-Control-GPIB-Serial/NI-VISA-status-code-not-decoded-on-Linux/td-p/1035064, which recommends updating your drivers.

[Camil]

pretty sure, everything is up to date, every thing have been installed today.

If it is a driver issue it would probably not work on the second attempt neither.

By the way, I use Matlab 2011b, windows 7 x64.