Using LabVIEW to write a VeriStand Custom Device

[joedowdle]

Hi everyone,

I have been put in charge of creating a VeriStand custom device and I have never done it before.  I also haven't used VeriStand before so any insight could be helpful.  A short summary of the project is as follows:

I havea real-time system running test simulations and I want to use a DAQ external to the real-time system to gather data at a faster rate then the overall simulation runs at.  I don't have to worry about sending the data I gather back to the test running in VeriStand; I simply need to log it.  That being said, my custom device needs to allow the user to set which channel to use and whether or not to use a software or physical trigger to start/stop the data gathering when the simluation starts/stops.

I have been reading up on and playing around with custom devices as much as I could the last few days and here is about where I am at:

I know there is a custom device template tool to generate a custom device LabVIEW project.  Based on the requirements of my custom device I have decided that it should be have an asynchronous execution type and the start/stop triggers can be sent across the Device Inputs/Outputs FIFO.  I also have [independently] built a VI that can sample signals using a soft button start/stop in conjuction with a SignalExpress express VI.  This is what I plant to use for the software trigger acquisition.  I plan to use the DAQmx trigger properties (start.trigtype, start.trigsrc, ref.trigtype, etc.) for physical triggers.  Right now I'd like to concentrate on the software triggers and implement the hardware triggers later on. I feel that this would help simplify my task.

The hardware my custom device is using is a NI cDAQ-9178 chassis with an NI-9227 analog current input device.  The software I have access to is LabVIEW 2011 SP1, VeriStand 2011, SignalExpress 2011, FPGA Module, RT Module.

Thanks for any help and ask for any other information you might need and I will do my best to provide it.  Thanks.

[Samuel_S]

Hi Joe,

You are correct I would definitely begin by looking at the custom device template and the current custom devices (you can download them and open the source code to see a good starting point for how to start)

However it may be easier to just make a model that has a configurable trigger lines that controls the DAQ device and then use the Stimulus Profile to log the data whenever you want.

If you decide to go the custom device way here are some good starting points:

http://www.ni.com/white-paper/9348/en

http://www.ni.com/white-paper/13604/en

http://www.ni.com/white-paper/9349/en

https://decibel.ni.com/content/docs/DOC-9891

[joedowdle]

Thank you for the reply.

I have tried to go through the "Building Custom Devices for NI VeriStand"  tuturial with the RT Logging files but it doesn't work.  I am running VeriStand 2011 and I can't remember exactly, but it says something on the basis of not being compatable and that I need VeriStand 2010.

Is there a version of these instructions that will work for 2011?

I will continue to keep looking through the information that you gave me. Thank you.

[Samuel_S]

Hey Joe,

There is not a new version of that Document published for 2011 explicitly; but the links above should be upto date with the necessary changes made for 2011.

[joedowdle]

This is the error I get when I try to open the RT Logging custom device.

[Samuel_S]

Joe,

That's error makes sense you are trying to run a custom device created in 2010 in 2011. I would recommend either modifing the VI in 2011 only or begin with one of the custome devices created for 2011. You can find them either in the links attached above or by going to ni.com/veristand/add-ons

[joedowdle]

That's what I was referring to earlier when I was asking if there was an example for 2011.  There is no 2011 version of the RT Logging files available that I could find anywhere.  I will see if I can find a 2011 add-on and use one of those for an example to start with.