Labview can't see global channels

[CDancer]

This is the first time I have used DAQmx, so apologies if I'm doing something really stupid...

I'm using a PCI-6221. I have configured a number of global virtual channels. However, when I try to access any of them in Labview, they are not there.

If I use Get Channel Information.vi, it always returns error -10003. If I try AI Acquire Waveform.vi, running it as a stand-alone vi, when I click on the channel input selector and choose Browse, I see "Select Names", and an empty listbox.

This is a brand new install of Labview 7.1. I'm using Nidaq 7, version 7.4, installed from CD this morning.

Chris

[Sarah_Coleman_NIUK]

Hi Chris,

It sounds like you're using traditional DAQ rather then DAQmx. At least the function you're referring to is a tradition DAQ function. The PCI-6221 will only work with the DAQmx driver which is why you aren't seeing your device listed when you use the traditional DAQ function.

The DAQmx functions are located under the NI Measurements palette >> DAQmx - Data Acquisition.

If you're just starting off with this you should have a look at some of the examples that ship with DAQmx. Open up the NI Example Finder by going to Help >> Find Examples... Then browse to Hardware Input and Output >> DAQmx and choose the type of functionality you want.

Let me know how you get on and if you've any further questions.

Kind regards,
Sarah

National Instruments | UK

[CDancer]

Sarah,

Yes, the realisation has slowly dawned on me that DAQmx is not backwardly compatible with the traditional DAQ vis. This is horrible - I have spent the last week writing programs for a customer, and naively assumed that what I wrote for my old DAQ card would work with their new M series card. So, not only do I have to radically re-write all my programs, today, but when I get home I have to buy a new M-series card so I can support the customer.

Ah, now I begin to see NI's business plan...

Thanks for your reply. Time to get programming    😞

Chris

[Dennis_Knutson]

Many older DAQ boards are also supported by DAQmx. Look at the table at http://www.ni.com/support/daq/versions_pci_pxi.htm and see if the board you have is.

DAQmx has been available for a couple of years now (since LV 7.0) and is much better and easier to use, imho.

[Sarah_Coleman_NIUK]

I shall quickly swoop in with a possible solution before you go buying more hardware...

It's possible to simulate devices with NI-DAQmx. This will allow you to support your customer without having to buy another M Series. See, we aren't just after you're money 😉

To simulate a device, right click on NI DAQmx Devices >> Create New NI-DAQmx Device >> NI DAQmx Simulated device. Then choose the device you need from the list.

You can interact with this the same way as you would with a real piece of hardware, you just won't be able to acquire any real signals. It will allow you to start programming without any hardware though.

In NI's defense, the reason for moving from NI-DAQ to NI-DAQmx was purely a performance upgrade. The DAQmx API is much more user friendly and I'm sure you'll have no problems learning to program in it.

Happy programming!
Sarah

[Sarah_Coleman_NIUK]

Just to follow on from my last post, the following tutorials should help get you started with NI-DAQmx.

This tutorial talks about the main DAQmx VIs, when to use them, how to program them etc... it's probably a good place to start:
http://zone.ni.com/devzone/conceptd.nsf/webmain/40522A58794A358B86256E7B006B8D69

Here's a more advanced tutorial that goes into some of the advanced features available:
http://zone.ni.com/devzone/conceptd.nsf/webmain/398AC5E81E683F7D86256FB9000D8717

And then here's the link to the Advanced DAQ section in the developer zone:
http://zone.ni.com/devzone/devzone.nsf/webcategories/8FCBE0A701B7075F86256F190045C220