Internal Channels Missing from Cards in NI-DAQmx

Issue Details

• I checked the internal channel option in I/O name filtering property. But, some X Series internal channels are not showing up. Why can't I access the internal hardware lines?
• I'm receiving error -200545, but I can't check the value of my internal reference voltage. How can I check this value?

Solution

For S Series and X Series DAQ devices, there is no internal channel list in the Physical Channels control in DAQmx.
 
For these devices, you can either acquire a signal present on the I/O connector, or you can acquire a signal that is being generated from the internal calibration multiplexer. The channels available on this multiplexer are typically used for calibration purposes, but you can also sample them as you would a physical signal present on the I/O connector.

To read from one of these internal channels:

1. Create a DAQmx Create Virtual Channel VI.
2. Right-click the physical lines input and click Create >> Constant or Control.
3. Select a physical line from your device such as Dev1/ai0.
4. Wire the DAQmx Create Virtual Channel VI into a DAQmx Channel Property Node.
5. Set the property to Write and select Analog Input >> General Properties >> Input Configuration >> Input Source.
6. Wire a string constant or string control to this property with the name of the internal channel you want to read (e.g., _calref_vs_aignd).

 

Additional Information

Take into account that this does not work for C Series modules. If you need to do this with a C Series module, the workaround is to use an input module to read the output module.