title: What can cause a GPIB to be unresponsive
body: <p>I have a GPIB device that I'm communicating with using a National Instruments USB to GPIB.  the USB to GPIB works great.  </p>
  
  <p>I am wondering what can cause a GPIB device to be unresponsive?  If I Turn off the device and turn it back on it will respond, but when I run my program it will respond at first.  It then cuts off I can't even communicate with the GPIB device it just times out.  </p>
  
  <p>Did I fill up the buffer?</p>
  
  <p><strong>Some specifics from another questioner</strong></p>
  
  <p>I'm controlling a National Instruments GPIB card (not USB) with PyVisa. The instrument on the GPIB bus is a Newport ESP300 motion controller. During a session of several hours (all the while sending commands to and reading from the ESP300) the ESP300 will sometimes stop listening and become unresponsive. All reads time out, and not even <code>*idn?</code> produces a response.</p>
  
  <p>Is there something I can do that is likely to clear this state? e.g. drive the IFC line?</p>