Hi all,
This is my first post, so bear with me if I don't add everything needed to answer this question.
I am using a cRIO (9074) in FPGA mode, along with a NI 9401 Digital I/O c-series and trying to output a square wave. This will then be sent to an external signal generator, which will boost the signal voltage so that the square wave can be used to trigger a plasma source (set-up to trigger on rising edge based on the external signal generator output). I have two questions that should help me complete this, one hardware and one software.
Hardware:
I am unfamiliar using the DIO / COM / NC pinout used in the NI 9401 (see pinout in attached manual, http://www.ni.com/pdf/manuals/374068g.pdf). I currently have my output wired to Pin 1 (DIO0) and pin 14 (COM). My understanding is that this will allow me to use DIO0 only. I have also ensure that DIO 0-3 are set to "output". Can you verify this is the correct pinout for receiving a digital output from DIO0? I am right now not seeing the signal at all on an oscilloscope, but realize the order of the two wires will be important in the future. Brownie points if you can also help me better understand the DIO / COM / NC trio, and what this is commonly used for.
Software:
In the attached VI, the "Control loop" contains a signal generator connected to the DIO0 output. I use "Plasma On?" in the GUI, and have verified that it is activating the "true" case. I should expect this to output the desired square wave, but have viewed nothing but noise on an oscilloscope.
I have alternatively seen physically setting the DIO to true and false, such as in the turbine example NI provides (www.ni.com/pdf/products/us/fullcriodevguide.pdf , pg 11, see picture). If there isn't an issue on the hardware side, can you shed any light why I am not getting a readable signal here?
Thanks so much, happy to provide more as needed