DAQmx show raw output?

[fborlc]

I am writing an array of doubles using the DAQmx write function. I would like to know what the raw / unscaled values sent to the Digital/Analog converter are. Is there an easy way to do this, such as a premade VI, or maybe a way to use a simulated device as a loopback in NI MAX?

[amezam]

Hello fborlc,

Take a look at this knowledge base. It explains how to use the DAQmx API to read the values written to an analog output channel using internal channels. It has an attached example. If you want to read the raw data then configure the DAQmx Read.vi for More>>Raw.

Best Regards,

Alina M

[fborlc]

Thanks, this is really good information! Unfortunately I am using a USB-6366 and these internal channels don't seem to be available.

[amezam · Accepted solution]

Hello fborlc,

Looking at the DAQmx help for X Series Simultaneous Sampling devices (like the USB-6366); it seems you should be able to use the Internal Channels with Channel Property Nodes. If you check the help information, it states that using the device’s AI physical channel (for example, Dev1/ai0) for the DAQmx Create Virtual Channel VI specifies the ADC for the internal channel. You can then set the appropriate string value on the Input Source channel attribute/property. If you place a Channel Property Node in the block diagram, configure it for Analog Input>>General Properties>>Input Configuration>>Input Source, you should be able to use this feature. I don’t have one of these devices at hand, so I couldn’t test it, but you could try this suggestion. I found this information by searching for Internal Channel X Series in the DAQmx Help file.

Regards,

Alina M

[fborlc]

Thank you! That's just what I needed. I shouldn't have given up so easily 🙂