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USB 3 question



has anyone had any trouble with USB 2 to USB 3 connections?

I like the idea of the increased band width of USB 3 but most of the connections from my equipment is USB 2.

will I have to buy a powered USB 3 hub to take advantage of the USB 3 capabilities.




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I use the following mains powered USB 3.0 hub located at my mount. I purchased the kit through Amazon UK 


Mains powered USB 3.0 hub




10m USB 3.0 active lead




Previously I used to run out 2 x USB 2 active leads to prevent them being overloaded and either my guide camera or 650D from disconnecting due to the USB 2 connection to the powered USB 2 hub I had (1 lead for the mount and 650D via the hub, the second lead directly to the guide camera QYY 5L- ii) from being over subscribed and therefore dropping or corrupting packets.


What looks to be happening with the new arrangement is that the connection from the USB port on my Laptop to the hub is running at USB 3.0 speeds and the ports the other side of the hub are running at USB 2 (as that is what all the connected kit is), I haven't tried to connect a USB 3.0 device at the same time as I have USB 2 devices connected to the hub to see what speed the USB 3.0 devices would work at, I suspect that once a USB 2 device is connected all the ports may be restricted to USB 2 speeds, though as stated I have not tested this arrangement.


I have been using this configuration for about 6 months and have not had a camera or similar disconnect.


For me this configuration works.


A note of caution, The 10m lead above is the second one I tried as the first 5m lead (ordered in error) that I tried simply did not reliably deliver USB 3.0 speeds to the hub when I tested it, so I sent it back and ordered the one above which when tested always delivered USB 3.0 speeds through any of the ports on the hub (testing the data transfer rate from a PC to the hub one port at a time).



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From my reading, USB 2.0's device's bandwidth will not be aggregated with a USB 3.0 link to the computer. Total available bandwidth will still be 1 USB 2.0's worth. 


See here http://www.otelescope.com/index.php?/topic/909-usb-30-applicability-to-astrophotography/#entry6598


Specifically: http://electronicdesign.com/embedded/what-s-difference-between-usb-20-and-30-hubs


This shows the USB 3.0 pinout, with the separate wires for USB 2.0 called out" https://en.wikipedia.org/wiki/USB_3.0#Pinouts

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Thanks for all the info.

the configuration I have now is similar to Jim's with the USB 2. I was hoping to be able to get rid of at least one cable.

which looks like I will be able to with a USB 3 hub.

I am running a Canon T3i, a motorized starlight focuser, through a USB 2 hub, and a  Orion "StarShoot" guide camera.

I have had to run a separate cable for my Guide camera in order to have it work, it would not work through the USB 2 hub with everything else.


I have not tried to connect my mount to the computer yet as I have not found a decent software package that will interface with my CGEM-DX at a reasonable price.

that will be a different post. one thing at a time.

I am looking at StarTech.com USB 3 hub # ST4300USBMS

thanks again

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You can save USB bandwidth, from your guide camera, if it supports "subframes" (I've forgotten if the SSAG does, the "pro" version does). 


In PHD2 click on the brain icon and then the camera tab. There will be checkbox for subframes. That will mean only small area around the guide star will be transferred to your computer, vs. the full frame.


You may wish to keep it disabled until after calibration.


I run a T3i, QHYD5L-II guide camera, filter wheel, focuser, and mount, over one USB 2.0 active cable. I have a metal 12v. powered USB 2.0 Hub.

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Cartes du Ciel is a free planetarium program with support for ASCOM telescopes/mounts like your CGEM DX.

BYE Premium version also has support for ASCOM telescopes. The upgrade from Classic to Premium is very reasonable.

AstroTortilla will use BYE and ASCOM telescopes to achieve hi-accuracy telescope pointing.


Not that I am trying to overload your USB hub, but there is some advantage to connecting your DX to the PC.

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dts350z, Rick


Thanks, Ill look into both of your suggestions.

I hope the 4 port hub I am looking at will be enough.


My Toshiba laptop that I have been using lost the USB 3 and a USB 2 port so all I have now is 1 USB 2 port.

I am in the process of buying a new laptop as we type so all I have to do is get it delivered.

this is why I am thinking of upgrading my powered hub to USB 3 while I'm in the process.

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Having a High-Quality Powered USB3 Hub as part of your new Laptop Gear will likely be a "Very Good Thing" for you.  However, one can never account for any "Incompatibilities" with Older Gear that runs on "Slightly Flawed" USB2 Implementations (usually an issue with the Interface Chip used in that Old USB2 Device).  One can never really tell until one tests it out...  Going with a Quality USB3 Device is your "Best Defense", and StarTech is one of the Brands that fits the "Quality" Description.


You might want to consider a different Model of StarTech USB3 Hub, however.  The model you've listed is made for a Permanent Wall-Mount Application, with several Sharp-Cornered Flanges that would almost Guarantee to Snag and Scratch your other Gear.  It also looks to come with Bright Green Indicator LEDs (not as bad as Intense Blue, but...).  Perhaps this Model with 4-Ports - its a Plastic Shell but only 1-LED; or this 7-Port Metal-cased model with Orange LEDs.


The other Brands that I've found successful are Anker and Belkin...

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the main reason I am looking at that model of hub is I can power it directly from my 12v battery.

as far a the LED's a piece of black electrical tape usually cures that problem.

and as far as the sharp edges a pare of tin snips and a file usually takes care of that.

I also usually mount the hub directly to my mount so it moves with the majority of the cables.

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OK, if the Original Item's Form Factor works for your Application, then by all means - StarTech produces Good Stuff.


Btw:  Both of the Items that I Linked can be powered by a 12V Battery - the 7-Port directly as its input is 12V and the 4-Port by a simple Lighter-Plug 5V Converter.

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Thanks for the Info.

I did not look at the 7 port that close I thought it needed a adapter but did not realize it was 12V.

I may go with that one because it gives me expansion capabilities if needed.

I am trying to get rid of the adapter if possible.

I did not mention that I run all my cables through 1/2" braded stretch plastic tubing to help if not elevate snagging.

here is a link. www.cabletiesandmore.com/american/catalog/inch-black-size-range-foot-p-248.php 

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The Anker device I use (and linked above) is also 12V DC, though it does have a plastic case and a blinding blue LED on each port.


Jim(wc6491), I use plastic spiral wrap to control the cables between my pier and the moving scope to prevent snags in much the same way as you are doing. Since doing this I have had far fewer unexplained sudden excursions on my pictures.



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