LabView compatability USB-6421

[leonloui]

Hey,

I bought a brand new USB-6421 for a new measurement task and today I tried in vain to get the USB-6421 device up and running.

Unfortunately without success, the device is not properly recognized by LabView. We work with LabView 18 and therefore also with DaqMX 18.

As I understand the NI homepage, I need DaqMX 24.1 as the driver for the device - but unfortunately this is not compatible with LabView 18.

Is there any way to run the USB-6421 device with my version of LabView 18?

Greets Leon

[santo_13]

That is a tough situation. As you know, the mio-DAQ series was launched in 2024, which means only DAQmx drivers released in 2024 or later will know that 6421 is a DAQ.

DAQmx driver supports up to 3 previous LabVIEW versions, and I believe starting v19 or 20, the drivers became LabVIEW version agnostic. So, you have a set of incompatible software and hardware.

What do you intend to do with the DAQ in LabVIEW? Will FlexLogger work for your needs?

[leonloui]

Hey Santosh,

thanks for the quick answer. I hoped to hear sth. else tho 😉

I have a complex LabView programm which combines different datasources. I wanted to use the 6421 for adding some new analog signals to it. I guess Flexlogger is not an alternative there.

Greets Leon

[santo_13]

There may be a way, but it is not simple enough; you can still install the latest DAQmx version, and it will put the latest VI wrappers in a common location. If you have another machine, use the latest LV version to downconvert these latest DAQmx wrappers to LV18 and copy it to the instr.lib folder of LV2018.

With this, you got the latest driver dll working with LV2018.

Note: this is based on an understanding of how things work under the hood and is not verified to be working.

[leonloui]

Thanks for this approach. I didn't test it and decided to buy a licence for LV 24 as I need quick solution. Leaves me a bit disappointed about NI compatability, especially with such a 'casual' device. With 3rd party hardware that wouldnt have happened. Better luck next time...

[leonloui · Accepted solution]

I found a solution: I had another idea, namely to integrate the device with Python using the Python block I have in LV18. To do this, I only installed the C compiler from DAQMX 24 as in the attached video (https://www.youtube.com/watch?v=hQMl3SHMLjg).

When I opened my program to implement the Python block, I then miraculously had my old DAQmx18 in LabView and the mioDAQ was recognised as a Device. So it's done, it works now - even without Python.

[rolfk]

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@leonloui wrote:

I found a solution: I had another idea, namely to integrate the device with Python using the Python block I have in LV18. To do this, I only installed the C compiler from DAQMX 24 as in the attached video (https://www.youtube.com/watch?v=hQMl3SHMLjg).

When I opened my program to implement the Python block, I then miraculously had my old DAQmx18 in LabView and the mioDAQ was recognised as a Device. So it's done, it works now - even without Python.

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The potential problem with this is that the LabVIEW VI bindings installed in your LabVIEW folder are from DAQmx 18.0 while the underlaying DLLs are from DAQmx 24.x. While the DAQmx API is relatively stable there is NO guarantee that there are no APIs that have somehow changed, either in functionality or even datatype interface. This could mean that certain DAQmx VIs will actually mismatch with the underlaying DLL interface and may cause unexpected operation or simply a hard crash. It's not likely (but still possible) for the most basic DAQmx operations as they have been in DAQmx for many years but if you ever venture into more esoteric areas, things definitely might be going wrong.

So thread carefully here!

As to supporting old versions of software with newest hardware and vice versa: Everything NI claims to support needs to be tested rigorously.  With n OS versions, m LabVIEW versions, k hardware products and l OSes, this amounts to a n * m * k * l effort to test for every release. If they maintain to many n, m, k, and l you won't ever see new releases since they are simply to expensive to test!