title: VI_ERROR_TMO (-1073807339)
body: <p>I'm using RS-232 port to communicate with KeithleyInstruments(SCPI Protocol) and have a problem.I can send the write command but when I send a query command it*s show the error below.</p>
  
  <pre><code>import visa
  rm = visa.ResourceManager()
  inst = rm.list_resources()
  print inst
  # print inst --&gt; (u'USB0::0x05E6::0x2200::9060025::INSTR', u'ASRL1::INSTR', u'ASRL6::INSTR', u'ASRL7::INSTR', u'ASRL10::INSTR', u'GPIB0::16::INSTR')
  keithleyInst= rm.open_resource('ASRL7::INSTR')
  print keithleyInst.write("*rst")
  print keithleyInst.write(":meas:temp?")
  print keithleyInst.query(":meas:temp?")
  </code></pre>
  
  <blockquote>
    <p>Error:</p>
  </blockquote>
  
  <pre><code>pyvisa.errors.VisaIOError: VI_ERROR_TMO (-1073807339): Timeout expired before operation completed.
  </code></pre>