Can 8 units of USB-6509 work at the same time using USB hub connected to one PC?

[JiaLiGenmark]

Dear,

       I currently using 2 units of USB-6509 and Labview 8.5 which works fine by defining two DAQ assistant in my Labview program. For the new system, we are going to use 8 units of USB-6509, will they work at the same time by connecting all of them to one PC using USB hub?

Thank you,

Best,

[crossrulz]

At that point, I would be more inclined to go with the PXI route.  It would be a lot more reliable.  I do not trust USB for test systems.  I have had way too many issues.

[Minions]

The answer is yes, but probably not in the manner that you are thinking.  All of the USB-6509 devices will work; however, it comes with a limitation.  These devices will not be able to work simultaneously as only one can be addressed at a time.  They will work and require some programming and a latency understanding as there is only a single USB port that gets distributed out to each hub, port, mouse, keyboard,... all share.

[JiaLiGenmark]

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@crossrulz wrote:

At that point, I would be more inclined to go with the PXI route.  It would be a lot more reliable.  I do not trust USB for test systems.  I have had way too many issues.

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Thank you for your suggestion.

I checked PXI solutions, including chassis, controllers. For working with a laptop, it either needs a PCI express card or a thunderbolt 3 port. Unfortunately my laptop has none of these ports.  

[Albert.Geven]

It all depends on the speed and accuracy that you need.

What are the specs?

[JiaLiGenmark]

Dear,

       Thank you. My specs is not that strict. I need all 8 units of USB6509's Digital IO to be refreshed every 1mS. There's a while loop, within the loop, 8 "write task" is assigned to each of the USB6059. I need each iteration of the loop to be completed within 1mS. In considering connecting all of the 8 units of USB6509 in a USB hub which connects to my laptop. Each USB6509 has 96 digital IO output needs to be refreshed.

Best,

[crossrulz]

If you insist on sticking with USB, then get an industrial hub with plenty of power capability, including an external power supply.

[Minions]

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@JiaLiGenmark wrote:

Dear,

       Thank you. My specs is not that strict. I need all 8 units of USB6509's Digital IO to be refreshed every 1mS. There's a while loop, within the loop, 8 "write task" is assigned to each of the USB6059. I need each iteration of the loop to be completed within 1mS.  

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Are you using a real-time system?  If you are dependent on a windows-based machine, your loop times will occasionally exceed your 1mS requirements.

[crossrulz]

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Minions wrote: If you are dependent on a windows-based machine, your loop times will occasionally exceed your 1mS requirements.

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From what I am quickly finding out on the web, the latency of the USB communication could be in the 1ms range.  So there are many problems with the current requirements.  I see this as another reason to go with PXI, where the latency will be in the sub-us range.

[JiaLiGenmark]

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@Minions wrote:

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@JiaLiGenmark wrote:

Dear,

       Thank you. My specs is not that strict. I need all 8 units of USB6509's Digital IO to be refreshed every 1mS. There's a while loop, within the loop, 8 "write task" is assigned to each of the USB6059. I need each iteration of the loop to be completed within 1mS.  

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Are you using a real-time system?  If you are dependent on a windows-based machine, your loop times will occasionally exceed your 1mS requirements.

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Thank you. I am using windows. If it only happens occasionally, it's OK for my application.

Your first reply triggers me to order 8 of USB6509 and give a try. I will keep this post updated when I get any results.