USB-6211 + LabView for automated tests?

[thobson]

Hi there,

My company is currently setting up automated testing for our PCBs in the factory, and we're trying to figure out if an NI DAQ such as the USB-6211 would be suitable for our needs. 

Our test requirements are fairly straightforward: measure voltages at different test points, input test signals, measure the resultant outputs and run some simple analysis on them. We need the tests to run quickly and automatically, so that the results can be easily interpreted by someone on the assembly line. The device also needs to be low-cost. We can't afford the higher-end NI test solutions.

I'm sure that something like the USB-6211 paired with LabView would work fairly well for this, but the main question we have is over the development time/learning curve. We need something we can deploy quickly. In other words, we don't have a lot of time to dedicate to sitting down and learning a whole new software/programming framework, even if, once learned, it is very easy and quick to use.

Do we have to use TestStand in addition to LabView? There aren't a large number of different test sequences to manage, so maybe it isn't necessary?

Is it possible to interface with NI's DAQs through other programming languages, like C or Python? Is there a way to automate an NI DAQ without using LabView (apologies if this is a sacrilegious question)? If not, is it realistic to dive into using LabView with little or no experience and get a working test solution (in terms of software, not the physical test fixtures) up and running in a matter of a week or two?

These are fairly general questions, I know, but thanks for your attention and help!

[SnowMule]

I've got 621x's in a few test fixtures here.  Look at the specs and buy what you need.

DAQ calls go through DAQmx.  In LabVIEW, it's pretty easy to configure and read.

TestStand is its own thing.  Unnecessary if you've got LabVIEW and wish to do your development in there.  Depends on your test application.

Yes, there's DAQmx Libraries for other languages.  http://www.ni.com/white-paper/5409/en/

[thobson]

Great, so it looks like DAQmx is what I was after. Thanks!

Do you think it's possible to use multiple USB-6009s instead of a USB-621x type thing? We don't need a high sample rate. We're more interested in having lots of analog outputs. I'm just curious if its tricky to coordinate say, three separate devices from one machine with DAQmx.

[SnowMule]

Done that too.   Setting up multiple devices can be a bit of a headache for manufacturing, but you can use DAQmx property nodes for model/serial numbers to identify what's what. 

Since it's all DAQmx calls, the functionality is all in your code.  Keep track of the Dev1/Dev2/Dev3 and tasks in a cluster (or better yet, an object). 

[thobson]

OK, perfect. 

Can you elaborate on why multiple devices complicates things in a manufacturing context? 

Thanks for all of your help so far, it's been great!

[Dennis_Knutson]

With multiple devices, you have to keep track of which device is which because the names can change when they are unplugged/plugged.

Also, the 6008/6009 is a bad choice for analog output unless it is strictly single point updates at a low frequency.

[SnowMule]

Because trying to figure out which part each of these DAQs is in can be a bit of a nightmare, especially if you have to set it up on another machine later.

[Henrik_Volkers]

Write down the specs you need!

Here, read X channels with Y accuracy (range U)  at Z samplerate and update A outputs to B levels at C updaterate, plus ??

Ask your local NI sales man.

If the device(s) don't meet your spec during the validation, it's less discussion 😉

Multiplexed inputs are cheap, but have some pitfalls.

And I assume you will need traceability / calibration capabilities  too

[Aaron_W.]

thobson,

Just throwing some other ideas out there. Have you looked at CompactDAQ? It's a modular platform similar to PXI, but cheaper. You would interface over USB and NI sells different cDAQ chassis that have 1, 4, or 8 slots. You can also interface over Ethernet, or wireless depending on how fancy you want to be. Take a look at the NI 9174 or 9178. Single slot module is the NI 9171.

You would buy the chassis you wanted, then fill it with the modules you need. There are many different types of modules so you can customize the setup as you need. You mentioned you needed a lot of analog output modules. For instance if you take a NI 9263 you would have 4 AO channels. If you place it with a single slot chassis (9171), your total price is about $665 (according to NI website). Since the 6211 only has 2 AO channels and is priced at $880, then you are saving money, assuming you only need AO. There are other modules to like the NI 9264 that has 16 analog output channels for $960, so price per channel is better than the 6211.

Point being, there are tons of modules within the cDAQ family, you can customize your system more than that of a USB DAQ device so you pay for only what you need.

I would also like to say, if you are not wanting to do this yourself because of time / knowledge considerations, look for an alliance member. They can help you spec out the right system for your application and develop you a turn key solution. I always like to point this route out to customers because I happen to be one.

There is a good directory here:

http://partners.ni.com/partner_locator/search.aspx

Hope this helps!

[thobson]

Thanks everyone for your help!

We're currently trying out some experiments that involve NI equipment, for now just a USB-6009 (I am aware this is not the right part, but we are just playing with it). 

CompactDAQ does look intriguing, but it's still a little expensive. To me, all of the USB-6XXX seem expensive for what they are, although I'm sure plenty of people will disagree with me and I'm not particularly interested in having a debate about it. If we have to go the route of solving the problem with money, then we will, but for now we're exploring using a mixture of equipment to create a system that can do analog in/out easily and in an automated way that we can write code for.

I'm actually having a bit of a hard time with the USB-6009 as it is, so I'm blocked on the part selection decision, and I think I should post a separate question about that issue.

I'll let you know how it all goes, hopefully! Thanks again!