title: Read-Out of two channels of National Instrument USB 6211 with python
body: <p>I'm trying to read out two channels simultaneously if an USB 6211 with python. To that end, I tried to adapt the example from <a href="http://www.scipy.org/Cookbook/Data_Acquisition_with_NIDAQmx" rel="nofollow">http://www.scipy.org/Cookbook/Data_Acquisition_with_NIDAQmx</a> by changing the line</p>
  
  <pre><code>CHK(nidaq.DAQmxCreateAIVoltageChan(
          taskHandle,
          "Dev1/ai0",
          "", 
          DAQmx_Val_Cfg_Default, 
          float64(-10.0),
          float64(10.0), 
          DAQmx_Val_Volts,
          None))
  </code></pre>
  
  <p>to</p>
  
  <pre><code>CHK(nidaq.DAQmxCreateAIVoltageChan(
      taskHandle,
      "Dev1/ai0:1",
      "", 
      DAQmx_Val_Cfg_Default, 
      float64(-10.0),
      float64(10.0), 
      DAQmx_Val_Volts,
      None))
  </code></pre>
  
  <p>But then, I keep receiving the error message that "nidaq call failed with error -200229: 'Buffer is too small to fit read data". Adding the line <code>CHK(nidaq.DAQmxCfgInputBuffer(taskHandle, uInt32(10000000)))</code> or increasing the length of the data array did not help...</p>
  
  <p>Could someone point me to the right variable to change?</p>