DAXmx Task Timeouts.

[DieselPower]

I have 12 installations of a PXI-8840/PXI-1082.  Each one has 2 or 3 USB connections to cDAQ-9178 chassis.  Software is CVI 2019 with RT module.  One chassis is close enough to use the OEM USB cable.  The other chassis is 30-35 ft away.  We are using a USB-powered range extender cable to reach the further one.  We used the same hardware setup when using the Windows PC as our DAQ PC before switching to PXI.  The Windows version of my software which creates tasks in the same way that the CVI/PXI version does, rarely had any issues.  If it did, it was recoverable by simply restarting the program.  If the issue was ever common, we would replace the USB cable, but this was rare.

The PXI seems to be much less forgiving.  When it happens, the AI task generally faults, but the AO module seems to always be the culprit when trying to restart.  I've found that I have to reset the cDAQ chassis SEVERAL times.  Each time I reset I then check the modules until I find one that is unresponsive.  Then I reset the CHASSIS again.  It will generally correct at least one module per reset, but again it takes several resets to make all modules responsive.  This is an onerous process in general, but even more so when you have to convey it to the night shift.  I'm starting to think that our only solution is to bring the chassis closer to the PXI, but that will increase the signal wire length.  It is not ideal at all. 

Question 1: Why do the PXI drivers (18.6 which I'm stuck on) seem to have more issues with this timeout?

Question 2: Why do I have to reset the cDAQ chassis so many times to get the modules responsive again.

[santo_13]

I bet the USB driver stability with the USB Powered extender is the culprit.

[DieselPower]

Any recommendation on the best possible extender I can buy?

[santo_13]

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@DieselPower wrote:

Any recommendation on the best possible extender I can buy?

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Going by the reputation of the Eaton brand, please check https://tripplite.eaton.com/products/usb-extenders~332

Startech also has a good reputation on the quality and reliability of the products https://www.startech.com/en-us/cards-adapters/u01043-usb-extender

But! there is no guarantee that this will solve your problem but a good faith attempt.

[DieselPower]

We are already using the Tripp-Lite model because of the name recognition.  As we discussed this at our morning meeting today I Googled about using the USB 3 port for a USB 2 device at extended ranges.  Google AI states that I should have better performance using the USB 3 ports on the PXI-8840.   Not in speed, but it noise reduction over distance.  We are giving that a try.  We've have this timeout three times in 30 hours in one cell, so we should know soon if it is an improvement.

Yes, even when using a USB 2.0 device on a USB 3 port, you will generally see slightly better performance at further distances compared to using a standard USB 2 port, as USB 3 has improved signal integrity allowing for more reliable data transmission over longer cable lengths, although the overall transfer speed will still be limited by the capabilities of the USB 2 device itself. [1, 2, 3, 4, 5]

Key points to remember: [2, 3, 5]

• Limited by the device: While the USB 3 port can potentially handle faster data transfer rates, if you plug in a USB 2 device, the transfer speed will be capped at the USB 2 standard, regardless of the port used. [2, 3, 5]
• Signal quality improvement: USB 3 technology generally has better signal quality over longer cable lengths compared to USB 2, which can result in slightly faster transfer speeds even when using a USB 2 device on a USB 3 port at further distances. [1, 3, 4]
• Maximum cable length: Both USB 2 and USB 3 have recommended maximum cable lengths, but generally, a USB 3 cable can be slightly longer while maintaining optimal performance compared to a USB 2 cable. [1, 4, 6]

Generative AI is experimental.

[1] https://www.anker.com/blogs/cables/usb-cable-max-length

[2] https://www.avaccess.com/blogs/guides/usb-2-0-vs-3-0-comparison/

[3] https://en.wikipedia.org/wiki/USB_3.0

[4] https://cie-group.com/how-to-av/videos-and-blogs/how-to-extend-a-usb-signal-transmission-distance

[5] https://www.verbatim.com/UserFiles/File/USB%203%20FAQs.pdf

[6] https://cabletimetech.com/blogs/knowledge/usb-cable-length-restrictions-how-to-bypass-and-extend

[DieselPower]

I moved problem chassis USB cables to USB 3 ports.  We have made a lot of progress on this problem, but one cell has done this 4 times today.  That makes this cell unusable.  Is there any way we can escalate this issue with NI Tech Support? 

I am taking a lot of flak because we didn't have this issue on my Windows-based DAQ system which at some point used the same DAQmx drivers (18.6), and the same USB chassis (9178).  I don't know what it is about the PXI DAQmx drivers that causes such a glitch where I have to go into max and reset the chassis several times in order to refresh all of the modules.  I really need to solve this problem, even if we have to pay NI to help.