Digital inputs to analog output using NI-6009

[chetansingh]

Hi Guys,

Any idea  if I can use NI-6009 as a digital to analog converter.
 In my application, I am generating 12 bit digital data from FPGA and I want to 
convert this to analog value to display it on Oscilloscope.

I have seen the user guide for 6009 but didn't find any relevant info that it 
can be used as Digital to Analog converter. 

It would be really helpful if you could suggest on this.

Thanks,
Chetan

[crossrulz]

The USB-6009 has 2 Analog Outputs.  So you just have to come up with a scale for your 12-bit values and output that voltage using one of the analog outputs.

[chetansingh]

Hi ,

     How could I sample all 12 bit digital input without clock and decode that to integer value? Then only I can send that to analog output channel.

I am new to labview, so I may be missing very trivial thing.

Thanks,

Chetan

[crossrulz]

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chetansingh wrote: How could I sample all 12 bit digital input without clock and decode that to integer value? Then only I can send that to analog output channel.

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You are sampling in your FPGA.  How are you getting that data to the host comptuer?  For sending the data out of the analog output, first we need to figure out a voltage to put out.  I would recommend using 10V as the full scale.  So since you have 12 bits and 10V full scale, your conversion is 10V/(2^12)*X, where X is the integer equivalent of your digital data.  Then you just use DAQmx to write the voltage out of the Analog Output.

I recommend looking at the examples that ship with LabVIEW for more information on writing to an anolog output.  The Example Finder is found by going to Help->Find Examples.

[chetansingh]

Hi ,

  Xilinx FPGA is providing 12 bit data on it's output pins, I am connecting all that 12 pins to NI6009. But I am not sure how to read these 12 pins and identify MSB and LSB and then convert to valid integer for analog output. 

Thanks,

Chetan

[crossrulz]

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chetansingh wrote:  Xilinx FPGA is providing 12 bit data on it's output pins, I am connecting all that 12 pins to NI6009. But I am not sure how to read these 12 pins and identify MSB and LSB and then convert to valid integer for analog output.

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In that case, I would setup two 8-bit ports on the Digital Inputs to read.  I'd go with P0 and P1.  You can then use DAQmx to read each port as a U8.  Use Join Number to bring the two 8-bit numbers into a 16-bit number.  You can then do the conversion to get the analog voltage you want and output using an Analog Output.

[Dennis_Knutson]

You can also setup the read for all 12 lines at once and return the data as U16. And remember that digital reads are software timed so you will have considerable jitter in the reads. Trying anything over 1kHz is just a waste of time.