DSC: Getting Periodic I/O Server to work

[David Moerman]

OK, I followed the instructions in the LV DSC 8.2 help on "Developing Periodic I/O Servers", but I can't get it to work.

After performing the build I wind up with a new .lvlib, containing my new I/O server.  Then I try to create a new shared variable that binds to this I/O server, so I select "Bind to Source", then "Browse".  I can see the new I/O server under the Project Items, but when I try to expand it there are no I/O items to choose from, the list is empty.

I've attached the VI that I'm trying to convert to an I/O server, if anyone has pointers your assistance is greatly appreciated.

--David Moerman

[DuffmanSays]

Hello David,

After creating a periodic I/O server from your VI, I can successfully browse to the items of your I/O server. After following the steps in the wizard, my project now has an I/O server to which I can bind shared variables. If you right click on the I/O server in your project and select "View I/O Items," do you see any of the items listed?

The items that should show up are those that you select during the second step of the wizard which creates the I/O server. You are prompted to place a checkmark next to the controls and indicators that you want to publish. Are you certain that you checked a few controls and indicators in this step? If none were checked, you will not see any items for your I/O server. I hope this information is useful for you. Please post back if you still experience any difficulty. Thanks,

Mike D.
National Instruments
Applications Engineer

[David Moerman]

Yes, I had checked off the checkboxes for all the I/O items, and performing a <right-click>View I/O Items on the I/O server reveals an empty dialog box.

Well, I just tested it on another computer with a fresh install of LV 8.2 DSC on top of a fresh Win XP Pro, and everything worked immediately.  I used the identical procedure for the 1st computer, and still can't get any of the I/O items to show up.  Any idea what may be causing this?


--Dave

[DuffmanSays]

Hello Dave,

That is definitely strange behavior that you are seeing on your first machine. I cannot find any documentation of why this may happen or other cases of this. To me there appear to be two potential causes: the machine on which you are developing or the integrity of the LabVIEW DSC installation on this machine.

I would be surprised if it were related to the machine itself, but to verify this, we can explore any of the major differences from the system on which this is working. Can you think of any significant hardware or software discrepancies between the two machines? Are they identical hardware? Do they use the same image?

It is more likely that there is a problem with the installation of DSC. Before we perform a reinstallation, we can examine this in a bit more detail. Have you ever been able to successfully create an I/O server? If you create a periodic I/O server from a new VI, does this give you the same problem? Do you have an OPC server on this machine? If so, can you create an I/O server and view any of the items in this project? If you'd like you might want to try downloading a free OPC server to test this out. However, you will most likely need to perform a reinstallation of the LabVIEW DSC module to get this back to normal. I hope this helps, and please post back and let us know what you find out! Thanks.

Mike D.
National Instruments
Applications Engineer

[David Moerman]

The two machines are radically different in both hardware and software.  The first machine is a development laptop I've used for 3 years, so there is a lot of stuff on it.  The 2nd machine is a clean install that I can re-image and use for testing.

Anyway, on the 1st machine I set up an OPC server using the Industrial Automation CD 5.1, which includes a "waveform" server that's useful to generate data.  OPC items show up with no problem, and I went and wrote a small VI that reads a shared variable linked to this OPC server and displays on a chart.  So I can see all that works fine.

At this point I suppose I will just go ahead and do a re-installation of the DSC module.

--Dave

[David Moerman]

I just did a "repair" of the DSC installation and now it works.

Thanks,

--Dave

[DuffmanSays]

Hello Dave, I am glad to hear that this worked for you. I apologize for the inconvenience, but it sounds as if it was the result of a bad installation. Thank you very much for posting back that this resolved the issue, and good luck with your application!

Mike D.
National Instruments
Applications Engineer