title: Trying to reliably communicate between Laser and PC via GPIB
body: <p>For my PhD, I am currently using a Tunics Plus Laser.</p>
  <p>I am able to perform several communications like:</p>
  <pre><code>import pyvisa
  
  gpib_address = pyvisa.ResourceManager().open_resource('GPIB0::10::INSTR') 
  gpib_address.write('L=1550')
  
  </code></pre>
  <p>which sets the laser wavelength for exapmle.</p>
  <p>Now there is also the command:</p>
  <pre><code>gpib_address.query('L?')
  </code></pre>
  <p>which should return the current laser wavelength.
  However, I do not reliably get an answer.
  I can't make out any cause, but it's rather arbitrary if or if not I get an answer.
  If not, it returns just an empty string, but not nothing?!?
  I tried by playing with the parameter query_delay, but that wasn't successful.</p>
  <p>I also use various other GPIB devices and have no problems with them. They work fine.</p>
  <p>Anybody has similar experiences?</p>