roboRIO usb

[denaliman99]

Does anyone know if you can use a usb hub on the roboRIO to increase the number of available usb ports to support additional cameras, etc.?

[cgmv123]

Hubs are part of the USB standard, so I don't see any reason why you wouldn't be able to use a USB hub. (I wouldn't be surprised if the 2 USB ports were 1 port connected like a hub internally.)

That said, make sure you either use a powered hub or make sure all the devices connected to the hub draw >900 mA/4.5 W total, the maximum current per port according to the roboRIO specifications.

[taichichuan]

Originally Posted by denaliman99

Does anyone know if you can use a usb hub on the roboRIO to increase the number of available usb ports to support additional cameras, etc.?

We've done it. It works fine as long as you don't try to pull too much current from the RoboRIO. 500ma is the max draw on USB 2.0. So, if you're trying to power 3 cameras, for example, you'll likely be in an overcurrent situation. Try powering the hub from a 5V supply and see if it works better for you.

HTH,

Mike

[cgmv123]

Originally Posted by taichichuan

500ma is the max draw on USB 2.0.

The roboRIO specifications document says the maximum draw per port is 900 mA.

[taichichuan]

Originally Posted by cgmv123

The roboRIO specifications document says the maximum draw per port is 900 mA.

Quite true. That is the number they list. However, that *is* in excess of the USB 2.0 spec. That number is in line with the USB 3.0 spec, but the port on the RoboRIO isn't listed as a USB 3.x device. So, yes, you *should* be able to get by with it. But, even though the RoboRIO can supply 900ma, it doesn't mean that your hub is built to handle that kind of current inbound from a single USB port. You'd still be better off with a powered hub, IMHO.

Good luck,

Mike

[cgmv123]

Originally Posted by taichichuan

You'd still be better off with a powered hub, IMHO.

Agreed.

[Merfoo]

Hello I'm trying to use a usb hub on the roborio to increase the amount of usb cameras we can use as well, the problem I'm having is that I can't get the images from the camera when it is plugged into the usb hub. I have tried two usb hubs, one that was powered from 5v and one that was not. The camera shows up on the roborio web interface when plugged into the usb hub that is NOT powered by a 5v but I'm still not able to get images from it in java. You guys have any ideas what could be happening? (Sorry if I threadjacked)

[Joe Ross]

Originally Posted by Merfoo

The camera shows up on the roborio web interface when plugged into the usb hub that is NOT powered by a 5v but I'm still not able to get images from it in java.

Have you changed the camera address in your java program to match the address reported in the web dashboard?

[crake]

900mA is indeed from USB 3.0 as roboRIO is designed to support USB 3.0 bus powered cameras, though at USB 2.0 rates.

[Merfoo]

Originally Posted by Joe Ross

Have you changed the camera address in your java program to match the address reported in the web dashboard?

By address do you mean the name, ex "cam0"? If so the name didn't change when plugged into the usb hub.

[Greg McKaskle]

As a point of compare, you may try launching Vision Assistant and choosing to Acquire images. You can pick the USB camera such as "cam0" in the list and see if it works there.

Greg McKaskle