Webcams and 7 Port USB Router


#1

Hello,

I am hooking up several USB webcams to a Plugable 7 Port High Performance USB router with 3 Amp power. No matter how I configure them, the computer only seems to stream two cams at once. Am I hitting the limit of the router’s ability to send info back to the main system? Or maybe just the maximum of the computer port? They are all recognized by the computer and can be accessed individually.

Any help would be appreciated, I’m not sure if this router will serve my purposes.

Thanks,

Ryan


#2

Hi Ryan,

Thank you for contacting us about your USB hub. I’m sorry it isn’t working as you expected. I’m not sure which of our hubs you are using. We sell both a USB 2.0 and USB 3.0 hub seven-port hub.

The hub should have the ability to supply power and a data connection to the computer to several webcams at the same time. At most the cams probably use a little more than 500mA, so the hub can likely power and connect six of them. The hub doesn’t care what it plugged into it, it just passes the information on to the computer.

The more likely issue is either that the data being passed by the webcams is exceeding the amount of data the computer’s USB port can handle, or there is a software limitation in the computer that limits the number of webcams that can be used simultaneously.

Here are some troubleshooting ideas:

  1. If you plug as many webcams as possible into a different USB ports on the computer (plug your keyboard and mouse and one cam into the hub), can you access them all? This would show if the single port the hub was in was the bottleneck.

  2. Does your software support more than two webcams? Can you open another program and add some?

Please let me know if these ideas help. If it turns out that the cams are not going to work with your hub, please feel free to return it under Amazon’s 30-day return policy. We don’t want you stuck with something that is not going to work for you.

David
Plugable Support


#3

Hi David,

Thanks for the response. The hub is for 2.0 USB, model USB2-HUB-AG7.

  1. Tried this morning and I get the same issue, with all previous devices running I can only run two cameras.

  2. Tried another software and same result. Also, running them simultaneously I can only see two total.

I’m thinking the problem is the computer’s ability to process the cameras. I had thought it was a tt problem, but this router is multi-tt, correct?

It looks like if I plan to use this computer it will need some hardware upgrades.

-Ryan


#4

Hi Ryan,

I suspect you’re right – you’re hitting a fundamental USB 2.0 limitation. USB has 4 transfer types: control, bulk, interrupt, and isoch. http://www.jungo.com/st/support/docum…

Each had different characteristics and goals. Webcams and audio devices use Isoch, because it’s the one transfer type that allows reserving a specific percentage of USB 2.0’s 480 Mbps max throughput put host controller.

So with isoch devices, you can only connect a certain number, before these reservations will have taken up the schedule.

The Terminus Technology FE 2.1 hub controller in the USB2-HUB-AG7 is multi-TT, but that should only be relevant for routing USB 1.1 through the hub, and I’m assuming these are USB 2.0 webcams.

I don’t know what your goal is for total number of webcams, but I suspect that hardware upgrades would be the most reliable way to get there – specifically, each USB host controller has its own 480 Mbps bus, so if you can split the webcams between several host controllers, you can reliably avoid any issues with throughput or reservations.

But this is definitely an interesting scenario. Thanks for asking and hope that little bit of background helps!
Bernie


#5