How reliable is USB for 24/7 use

[Colin hughes]

I have been informed that USB ports can drop out, requring a PC reboot.

But can not find any info with google.

I am thing of using the new NI USB racks for tempurture measurment for 1000 hour tests in our proving department.

The sofware is complete but untested as the tst rig has problems.

Currently the software is written to use the Measurement  Group USBTemp cards but these are not very robust as they are designed for desk top use.

Thanks

Colin Hughes

Delphi Diesel Systems

[TheWay]

Hi Colin,

The reliability of USB is dependent on many factors, most importantly, the operating system that is being used. Obviously, if your operating system crashes the USB device measurement will fail. For tests of that duration, I would not recommend using the USB modules unless you can reliably run the operating system for that long duration. Instead, I would recommend the LabVIEW Real-Time Module with a Compact Fieldpoint Controller and Termocouple Input Module. For more information on the Real-Time Module, please visit: http://www.ni.com/realtime/

Let me know if you have any other questions.

Regards

Way S.

NI UK Applications Engineer

[Colin hughes]

Hi Way

 I think we have the answer here.

We are using Windows XP Pro.

Some off our test are infact 4000 hour test that use USB CAN cards to control the ECU.

Test do stop for injector changes or oil changes but the computer is never shut down.

Asking around our proving department, no one has had a problem with the USB port droping out after month off leaving windows running.

But the CAN Card is only used when staring the test rig and not for logging data, so my qestion is still open.

I am looking at NI compactDaq but do not intend to use LabVIEW Real-Time.

I do not like programing in Labview at all as I prefer oject oriantaded programing using C++ or DOTNET to design highly modular software and not the mess that I see here with some off our in house Labview programers.

I do use Labview when programing FPGA but then compile as a DLL.

Thanks

Colin

[TheWay]

Hi Colin,

If your computer is able to run reliably on Windows XP Pro for that long, there is a good chance that the NI USB devices will work with your setup. CompactDAQ will definitely stay powered for that long period. It's the USB connection that cannot be guaranteed. The problem is there are too many USB chipsets out there to guarantee continuous data acquisition for such long durations across all of them.

Another possibility is to use a NI PCI DAQ board if your computer is close enough to the test rig. PCI boards are more reliable in a sense they don't have the USB connection complications.

Let me know if you have any other questions or concerns. 

Regards

Way S