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16 USB-6509s on one hub?

Hello,

 

We are currently running 16 NI-6509 DAQ PCI cards in a SuperLogics computer with a 16-slot PCI backplane running Red Hat Linux. Because 16-slot PCI machines are not common we were wondering if could convert to the USB version of the 6509 and use a more common machine to control them. One of the things these boards do is measure tachometer pulses on rack cooling fans. So each of the 16 boards polls its tachometer every 2 milliseconds. All 16 USB-6509s would have to run from the same computer/hub.


My question is would this work? 16 USB-6509s, all on the same USB hub and each polling their tachometers every 2 milliseconds?

 

Thank you,


Kevin Ryan
Software Engineer
National Radio Astronomy Observatory

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I would be more inclined to go with the PXI version (PXI-6509).  You would need to buy the 18-slot PXI chassis and a MXI connection.  But I would trust this A LOT more than a bunch of USBs.


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Yeah, that's why we are asking this question - to learn of others' experience using big'ish USB hubs in an industrial setting.  If you don't mind my asking, could you expand more on your inclination not to use USB? 

 

Thanks.

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I have had them come out of the jacks during transport.  If you do not plug them into the exact same jack, they show up as a different device, causing configuration issues.  Windows has "power saving features" of turning off USB hubs that has caused all kinds of issues.  It can become a wiring nightmare to keep all of those USB cables plugged into a good externally powered USB hub.  And since the USB-6509 is bus powered, you really have to watch your current consumption on the USB hub.

 

PXI just uses the PCI(e) bus.  One MXI cable to control all of the cards.  All of the cards are together in a single chassis, so transport is easier out of the box.  PXI has plenty of power for all of the boards.


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Transport and wiring will not be issues (it is a permanent installation and will not move)  and we are using Linux not Windows.  I am curious about your last statement about being bus powered - then what is the USB-6509 optional external 12-volt power supply for?

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@kevdev wrote:

Transport and wiring will not be issues (it is a permanent installation and will not move)  and we are using Linux not Windows.  I am curious about your last statement about being bus powered - then what is the USB-6509 optional external 12-volt power supply for?


That's what I get for not going through the specifications.  The 12V is used for additional current capacity instead of drawing it from the USB.  But do you really want to run power to all of your modules when you could just use 1 power cable with the PXI?


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Yes, I agreee, trying to rack mount 32-USB boxes and associated wall-wart power supplies does seem messy and fragile.  We'll probably stick with our PCI setup since we've got so much invested in it and just load up on spares while the 18-slot SuperLogics machine is still available.

 

I did check out your PXI chassis with MXI controller system and that looks very nice indeed.

 

Thanks for your thoughts!

 

Kevin

 

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