Data Acquisition Idea Exchange

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Standard wiring examples.

I'm not sure who reads this, but I'm not seeing any feedback in the forum so I thought I'd post up here. This may seem like a simple thing, but hopefully my pain will be someone else gain. I messed with this off and on for two months before I finally figured it out. It's probably obvious to those who work with this equipment every day and have EE degrees, but not so much to those of us who do not.

Please see http://forums.ni.com/t5/Multifunction-DAQ/Measuring-220VAC-with-CompactDAQ/td-p/1145956 for a description of the issues I was having.

Some will tell me to "search"... well, I did. ...and everywhere I looked all I found was that I needed to measure from the power leg to ground. All of the examples either were only measuring 120 which is fine since what you have is one power leg and neutral... which is basically ground! So those numbers come out fine. Or they were for 3 phase, which I don't use currently. BUT when you try and measure anything with two power legs (basically anything between 208VAC to 240 VAC) the numbers don't work out right if you try to measure between each power leg to ground and then try to recombine them and plug them into the Power VI's. Not one place that I looked did it tell me that I need to measure both power legs across a single channel. I only finally tried it because I'd done pretty much everything else. I know this is pretty basic stuff, but when all you give me says one thing... that's what we do. Just trying to help others.

Thanks,

Chad

As far as I know, the DAQ-mx has provicion to generate the COUNTER output or to read digital input triggered by the change detection event.

It would be nice if one is capable of generating the DIGITAL output on accurance of change detection event.(i.e. it can be triggered):smileytongue:

Also digital output must be allowed to generate the waveforms which are triggered by any of the digital input lines.

If possible then COUNTER counts should be available to user in LABVIEW after triggering, to synchronise the various digital input/output to counter state/count.Since some of the actions are COUNT dependent.

It has come up a few times from customers, and I wanted to gauge interest and solicit ideas on how this should work.

Currently, with the built-in TDMS logging support, if you want to change to a new file in the middle of logging, you need to stop the task and start again. For some use cases, this isn't practical (for example, http://forums.ni.com/t5/LabVIEW/Why-the-TDMS-file-is-larger-than-it-should-be/m-p/1176139#M511099).

The question is: How would you like to specify the "new file" behavior and what are your use cases?

For instance, a couple ideas to get the ball rolling:

Add an interval attribute like "Change file after n samples". We would then auto-increment the file name and change to that file when we have logged "n" samples.
Make file path attribute changeable at runtime. We have a file path attribute for logging. The idea here would be to support changing the file path "on the fly" without stopping and starting the task. The problem here is that it would not suit very well a use case where you want a specific file size. Additionally, it wouldn't be as easy to use as #1; it would be more flexible though.
(Any additional ideas/use cases?)

Thank you for your input!

Andy McRorie

NI R&D

It has come up a few times from customers, and I wanted to gauge interest and solicit ideas on how this should work.

The question is: How would you like to specify the "new file" behavior and what are your use cases?

What I'm currently thinking (because it seems the most flexible to different criteria and situations) is to simply allow you to set the file path property while the task is running (on DAQmx Read property node). The only downside I can think of with this approach is that you wouldn't know exactly when we change to the new file. We could guarantee within (for example) 1 second, but you wouldn't be able to specify the exact size.

Would this be a good solution for you? Can you think of a better way to specify this behavior?

I often use one DAQ device to test the basic functionality of another device and like to be able to quickly do this through test panels. Unfortunately, MAX does not allow the user to open more than a single test panel at once. The current workaround for this is to launch the test panels outside of MAX (see this KB).

It would be nice to have the same functionality when opening test panels in MAX. Specifically, I would like to be able to do the following with a Test Panel open:

1. Be able to navigate through MAX to do things like check device pinouts, calibration date, etc.

2. Be able to move and/or resize the original MAX Window (it always seems to be blocking other applications that I want to view alongside the Test Panel)

3. Open a test panel for a second (or third...) device.

It is nice that there is a workaround in place already but I think it would be nice if MAX had this behavior to begin with.

Data Acquisition Idea Exchange

Standard wiring examples.

Facility to generate "DIGITAL OUTPUT" on occurance of "change detection event".

Ability to split between multiple TDMS files while logging

Allow Multiple Test Panels Simultaneously Through MAX