datalogging 24 analog voltage channels between 2 x third-party DAQ devices

[SnowyEleven]

Does anyone have advice for a LabVIEW beginner who wants to datalog 24 x (8 & 16 differential) analog voltage channels (temperature) distributed between 2 x third-party DAQ devices (Exacq's CM series)? Durations of up to several days, and with measurement intervals in the order of every 1 sec to every 10 mins. n samples for each average/logged interval.

I have the drivers for the DAQs and they are working (e.g. analog input read volts). I've gone through various tutorials (on-line and from the LabVIEW manual) and am now familiar with the LabVIEW environment, but find them too simple for the task at hand. Without programming experience, it is not apparent - even with LabVIEW's graphical interface - to make use of existing VIs, especially since most are written to drive NI instruments only. Meanwhile, it seems 3rd party devices cannot take advantage of NI's Measurement & Automation Explorer (MAX) and DAQ Assistant, but I'd be happy to hear if this is actually possible. Perhaps complicating matters, the DAQ devices require use of Windows 2000 and LabVIEW 7 Express on an IBM Thinkpad T22. If finances were better, it would be preferable to use newer equipment, but this is not the case.

The only options I can see now are to learn LabVIEW and build from scratch VIs/subVIs using the 3rd party drivers. Or perhaps I could make use of the structure of any suggested existing LabVIEW VI (probably written for an NI device) and substitute where appropriate my 3rd party drivers.

Any advice on achieving the above, or taking alternative routes, is welcome. Thanks!

[LaThoS]

Hi SnowyEleven,

Unfortunately, MAX and DAQmx (the driver behind DAQ Assistant) only support National Instruments hardware. From what I have seen on the web, the Exacq CM series had LabVIEW drivers, but I cannot find them on our driver site (ni.com/drivers). As this is a legacy product, it may be hard to find them. If you do however, then they should add a function palette into the LabVIEW environment which lets you communicate with your device.

After having a search on the forum I found this post: http://forums.ni.com/t5/DASYLab/CH-series-exacq-driver-for-ver-11/td-p/1937863

You might have luck contacting Exacq and asking if they have the driver somewhere they could send you. If that isn't the case, try posting on the Multifunction DAQ forum asking if the community has a copy of the driver. If that doesn't help, then it may be time to upgrade...

Sorry I couldn't have been more help,

Laurence

[SnowyEleven]

Hi Laurence,

Thanks for confirming that MAX supports NI devices only.

As mentioned in the post I have the drivers; they appear on the palette in LabView and they work. As a LV beginner I'm seeking the simplest route to build the described datalogging system. Any tutorials on this, or other advice, which could help would be great.

[LaThoS]

Hi,

Apologies for not picking up on that. I think the best way forward would be to look through the DAQmx examples and try to replace the DAQmx functions with your 3rd party driver functions. Unfortunately NI can't support those drivers directly, but we can help with equivalent DAQmx architectures. If you find you are having trouble with a particular hardware function, then try posting on the Multifunction DAQ forum as well, as there are some community gurus who may have worked with those drivers before, and only subscribe to certain forums on this site.

As far as learning LabVIEW goes, anyone with a current standard service contract can now access our Self-Paced Online Training (SPOT) portal at http://sine.ni.com/tacs/app/fp/p/ap/ov/pg/1/sn/n5:selfpacedonline/

Alternatively there are some free tutorials at ni.com/tutorials/ as well as the examples which you have already found.

I hope this helps.

[SnowyEleven]

Hi Laurence,

Thanks for the self-paced learning link and tip on using existing DAQmx architecture.

For the latter I found this recent site: Index of DAQmx Shipping Examples (2011 and previous)

 (https://decibel.ni.com/content/docs/DOC-25713). Is this what you have in mind, or perhaps there any other resources available? At this point I'm simply determining which pre-existing architecture is the closest to my end-goal. I should mention I also have access (on a more recent computer) to LV 2011, and thought perhaps an example from there could be adaptable.

Since the first post in this thread I've managed to install LabVIEW 8.2 and read signals via the DAQs using the 3rd party driver. I installed LV 8.2 in the hope that the later version might enable the use of a greater range pre-existing architectures.

Lastly, do you or anyone else have advice about "LabVIEW Datalogging and Supervisory Control Module 8.2". It seems to be relevant to my application, but I'm unclear if it is even included in LV 7 or 8.2.

Thanks. Cheers!

[Dennis_Knutson]

As the product page states, it is an extra cost add on. Unless you need to communicate to plc's, opc clients, or use modbus, the DSC is probably overkill. Doing the logging is pretty simple if you have the acquisition working. You need to decide on the format. Do you want to save to a binary or text file? To a database? There are countless ways to save data and there many examples that come with LabVIEW.

[LaThoS]

As for architecture, producer/consumer is probably your best bet for this application. It enables you to queue up acquired data for processing and logging, while allowing the acquisition to proceed without any jitter or delay.

Here is a link to an example which demonstrates this. By looking at file writing examples in the LabVIEW Example Finder, you can change the logging stage to suite your needs.

https://decibel.ni.com/content/docs/DOC-2431

Hope this helps 

[unclebump]

Start with this pdf file. There should be a labview sdk somewhere on the web.

http://www.amplicon.com/data/ExacqCM.pdf

[unclebump]

Try this link for legacy downloads, but you have to register for it.

https://exacq.com/reseller/Legacy/index.html