USB device can perform faster

[Dave Crabbe]

John;

Does this mean NI should look at providing some external power for their USB modules?  

I haven't measured the specs of the USB devices to see what they draw, but that might be something to feed back into the designers.

Dave 

[John_P1]

Hi Dave,

Many of our USB products do in fact use an external power supply (e.g. USB 622x, 625x, 628x).  However there is still a specific market for bus-powered devices so we like to have options for these as well. 

Bus-powered USB 2.0 devices come in two categories:  low-powered and high-powered.  Low-powered devices can draw up to 100 mA over the bus, while high-powered can draw up to 500 mA (the maximum for a USB 2.0 port).  Our DAQ boards fall into the high-powered devices category.  These current limits are defined by the USB Specification (summarized in wikipedia article) which our boards are designed to work within.  If the USB port is shared by multiple devices or is not up to the High-powered 2.0 spec then the DAQ Device would likely be the one to expose the power problem since it requires more current than most typical USB devices.

If the powered hub is not an option another idea would be to try a USB Power Adapter Y Cable (like this one here).  The cable is intended to combine the power from two different USB ports and might be worth looking into as an alternative if the powered hub is impractical.

Best Regards,

[EMotts]

I think that this could be made more clear in the specifications or the user manual.  The USB-6008 manual does state the power requirements:

4.10 to 5.25 VDC.............................80 mA typical, 500 mA max

USB suspend ...................................300 mA typical, 500 mA max

But the ASUS mobo manual doesn't state its power capabilities, so I had no idea that this would be a problem.   And it's still not clear to me why Windows doesn't assign the USB-6008 to one of the ten open ports on the Enhanced USB Port, which had NOTHING else attached to it.  In the fact, I came across a Knowledge Base article on the Microsoft site that talked about a possible error message, on the lines of "This USB Port cannot supply enough power for this device."  But I had never actually gotten that error message, and the suggested actions were things I had tried before, so I disregarded that possibility.  They did not suggest adding an externally powered hub.

But I have a solution, and with Windows sometimes that's the best we can hope for.  Last night, I ran the USB-6008 through the USB hub on an externally powered HDD, and the 6008 appeared in the device manager under that hub, which was under the Enhanced Port.  So I ordered an externally powered hub from Newegg and should have that in a day or two.

Ed