How to communicate with instrument using USB port

Hello all!

Is there anyone who knows how to establish communication between Matlab and Intrument using USB port? I have the drivers of the instrument installed, but still not able to communicate with it.

Anyone who can help? I have never done this before...

Thank you!

[Michael Haderlein]

Did you check the Instrument Control Toolbox? I've personally never worked with it, but it looks as if you'd need to create a VISA-USB object. Then you can read and write messages as shown in the toolbox help. Everything else will strongly depend on your instrument.

[BSantos]

Dear Michael,

I did check it, but no budget to buy it. So, I was asked to do it, without. That Toolbox looked very handy but for now it's not an option...

Answer 1

[Jasmine]

First you'll need to open of the port. See fopen(serial) for help with this. You should be able to work out which COM port your instrument is on using device manager (assuming you are working on a windows platform). If for example you found it was on COM3 try fopen(COM3) . You could then use COM3.status to see if the port had opened, or try typing instrfind at the command line. Then how you communicate with it will depend on your instrument and what commands it understands. You may need to use fprintf(serial) to write text to a device or fwrite(serial) to write binary data to a device. See http://www.mathworks.co.uk/help/matlab/ref/serial.fwrite.html it has links to most functions for use with serial devices.

[BSantos]

Dear Jasmine,

thank you for your answer. I have tried some of these before but still not able to establish a successful communication.

s = serial('COM3');
fopen(s);
set(s,'BaudRate',9600);
fprintf(s,'*IDN?<cr><lf>');
out = fscanf(s);

But then, I get this warning message:

Warning: Unsuccessful read: A timeout occurred before the Terminator was reached.

I think this is an easy problem to solve for those who re used to work in this environment, but for me this is totally new. :)

[Joseph Cheng]

What instrument are you trying to talk to?

[BSantos]

A Pulse Generator: Quantum Composer 9520 Series.

Answer 2

[Jasmine]

Sounds like it is a terminator property problem. Try:

set(s,'Terminator',<cr><lf>);

and change your code to:

s = serial('COM3');
fopen(s);
set(s,'BaudRate',9600);
fprintf(s,'*IDN?');
out = fscanf(s);

See example: http://www.mathworks.co.uk/help/matlab/ref/serial.fopen.html

[BSantos]

Unfortunately, I can't change the code to your suggestion or what's on the example because that's not the syntax that my instrument uses. I have tried your suggestion About the terminator property but still no success.

Always get the same Warning message!

Anyone out there who might have worked with Quantum Composer 9520 Pulse Generator?

Thanks!

[Larry]

I suspect the documentation w/ <cr> and <lf> uses those character strings as placeholders for the ASCII characters. In Matlab use \r and \n. I.e. substitute '*IDN?\r\n' for '*IDN?<cr><lf>'.

Answer 3

[ozgur yildiz]

It is not a classic serial connection. Probably the device you want to connect, is identified by your computer since you've already installed the drivers (SDK) of the device. So you cannot see any occupied comport in Device Manager instead you can see the Device ID on one of the USB hub. So First you should indentify 'xxx.dll' files of the device in Matlab environment.