Digital I/O

Discussion in 'General Electronics Chat' started by Brian Robson, Feb 11, 2015.

  1. Brian Robson

    Thread Starter New Member

    Nov 13, 2014
    Not really sure where this question belongs, but I figured I would see if any engineers involved in system testing could answer this.

    I'm one of the engineers working on a Hardware in the Loop test bed. We have a need for digital I/O (32+ channels) that can be simultaneously updated by an external clock. We're using a real time PC and would like a PCI card. I had high hopes for using a UEI card. However, it turns out that the 64 bits are broken into 4 ports, which cannot be sampled simultaneously.

    I am having a hard time finding digital I/O that synchronizes to an external trigger/sample clock! Does anyone have any suggestions?
  2. Papabravo


    Feb 24, 2006
    Build your own. This product is probably too specialized to attract anybody to building it "on spec". How many do you want? If the answer's one, and the price was $5000.00, would you pay it?

    And therin lies the heart of the problem.

    If the answer was 100 @ $1000 each, then I might know a company that would do it for you.
  3. pwdixon


    Oct 11, 2012
    You could add something like 74373 latched buffers all clocked at the same time, of course you would need to synchronise the pc somehow. The I/O board you have chosen appears to have some interrupt inputs so with appropriate timing taken into account you could force the pc to set all of the outputs before the external clock next fires and passes the pc output through the latches. All sounds a bit vague but might solve your problem or at least trigger another solution.
  4. ScottWang


    Aug 23, 2012
    Using 74HC574 to expand the output ports or using the 74HC244 to expand the input ports.
    You can also using the arduino to communicate with PC and adding some 74HC574 or 74HC244 to expand the I/O of arduino.
  5. Reloadron

    Active Member

    Jan 15, 2015
    Measurment Computing comes to mind for the PCIE interface as well as other interfaces. Not sure as to the "can be simultaneously updated by an external clock". During my last few years before retirement we also did quite a bit of business with National Instruments. National Instruments was absolutely great with their help and support. We had some unusual applications and NI was right there with suggestion solutions. They have some of the best application engineers I ever had the pleasure of working with and they came right to us as needed. My best guess at this is to give them a call, either NI or MC. I really liked NI.

  6. AnalogKid

    Distinguished Member

    Aug 1, 2013
    Is your real time PC PCI, or cPCI (compact PCI)? NI's PXI bus is derived from cPCI, and they have an assortment of digital input and output cards. Still, that common latch thing is going to severely limit the field.

  7. pwdixon


    Oct 11, 2012
    Of course more info is required to determine the best options, what are the timing limitations on the system, an arduino solution would be real cheap and easy but might limit the throughput speed though for the right requirement would be a perfectly acceptable solution. It also depends on the end application, some industrial customers might sneer at an arduino solution and expect something more 'industrial'.