9205 Reads Same Voltage In All Channels When They Are Not Connected

Updated Jun 15, 2018

Reported In

Hardware

  • NI-9205

Driver

  • NI-DAQmx

Issue Details

I am reading several channels in RSE configuration using the 9205 module. The problem is that when some of this channels are disconnected, I'm getting the voltage value of the last one connected. How can I make the disconnected channels read 0 when they are disconnected?

Solution

Theare a couple of workarounds:
  • Set a pull down resistor in each channel that is disconnected. 
  • Use a simultaneous acquisition module like the 9220

Additional Information

The 9205 module has only one ADC shared by all the channels. When a reading is done, if nothing is connected to the next channel, the ADC reading will remain the same and the driver will take the value of the previous channel as the current channel value. In the NI 9205 Getting Started Guide the value of the inputs when they are disconnected is undefined. 

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