usb 6501

[snook]

I was given a USB 6501 DAQ CARD.  I will need to be able to generate a 64 bit serial word on one pin along with a clock on another pin for the purpose of loading an external DDS chip on another PC board..  The 64 bit word will be loaded only when one or more of the bits are toggled to select a different operation via labview front panel controls.  The 64 bit serial word will need to be synchronized to the rising edge of the clock.     My question is can the USB 6501 do this?  If so do you have any suggestions.  If not what NI DAQ card would you recommend using Labview?

Thanks,

Jim Cahoon

Rockwellcollins

jdcahoon@rockwellcollins.com

[Vanessa L]

Hi Jim,

I understand that you are using the USB-6501 DAQ card.  When talking about functionality of the card, it is important to look at both the driver software and the hardware that you are using.  First, are you using NI-DAQ (also known as Traditional DAQ) or DAQmx?  And what versions are you using?  This will be helpful information once you start searching for example programs using data acquisition that are provided with LabVIEW.

You will definitely be able to generate the clock on a single line of the USB-6501 card.  This can be done by utilizing the counter and doing a Counter Output operation to generate a digital pulse train.  Since the USB-6501 has one 32-bit counter, you can use the output terminal for your clock signal.  As far as the 64 bit word, I am assuming you mean a binary representation of data to be written out to one of the digital lines on the card.  When doing a digital output operation,you can go into the DAQmx category on your functions palette and select DAQmx Write.vi.  This VI can then be chosen to implement what type of digital data that you want written out.  You can choose the polymorphic selection at the bottom of the VI to go to Digital>>Single Channel>>Multiple Samples.  Then you can choose either 1D U8, 1DU16, or 1D U32 for array representation.  Since the USB-6501 has only 8 lines per port, you would choose the 1D U8 option for 8 bits of data representation.  For your application, this would not be enough representation.  However, as you can see the largest number of bits would be 32.

You might want to also look at the examples that are provided with LabVIEW.  These are found by going to Help>>Find Examples in LabVIEW.  Then choose the Hardware Input and Output>>DAQmx>>Digtial Generation or Generate Digital Pulses folder to get to Digital Out and Counter Out respectively.  I have assumed that you are using DAQmx in your application.  However, if you have the Traditional DAQ software, the examples are located in a different place.  When you open up the example finder, change the "browse according to" option to Directly Structure and then choose the daq folder to get to those examples.

Finally, in order to better understand digital output on the 6501, this user manual will provide you with more information.