Timeout expired before operation completed

g=visadev("GPIB::18::INSTR")

visadevlist and visadev are not supported on Linux.

writeline(g,"Display:Contrast")
data=readline(g)

Hello, I am currently trying to read and write to my PSA spectrum analyzer. visadev is successfully connecting it, but I writeline and readline, when added into my code, always get the "Timeout expired before operation completed" error message. I do not understand why this is not working and how I can fix it. Any advice is greatly apprectiated!

Answer 1

[Adit Kirtani]

Hi Madeline,

From the issue you have described in your question, I have understood that the write operation has not finished within the default time to complete a write operation. You can change this value by using the following code snippet:

timeout_duration = 20 %Change to whatever value you wish 
v = visadev( "GPIB::18::INSTR"); 
v.timeout = timeout_duration 
%Now perform your write / read operations 

You can view more details regarding the read and write properties of the visadev object using this documentation link:

https://www.mathworks.com/help/instrument/visadev-properties.html

I hope this helps,

Adit Kirtani

Answer 2

[Andrei]

A couple of suggestions:

• Check that the SCPI command is correct. Not sure what the instrument model is, but I don't see this command in Keysight's PSA Spectrum Analyzer User's and Programmer's Reference Volume 1 - Core Spectrum Analyzer Functions (keysight.com)
• If you are expecting a response from the instrument, the command string should have a ? at the end. In that case instead of writeline followed by readline you can also use writeread function. For example writeread(g,"*IDN?")

See also:

https://www.mathworks.com/help/instrument/visadev.writeread.html

https://www.mathworks.com/help/instrument/visadev-warning-unable-to-read-any-data.html