USBs, Ports and Hubs

[BC]

I’m working away at getting things set up for imaging with the hope of connecting the mount, the camera and the webcam to a netbook via ~5m of cable. I have successfully got Stellarium Scope working fine with the EQ6. Despite having 3 USB ports on the netbook, Stellarium Scope only works on one of the USBs. The 500D will also only work on one USB; the same one as Stellarium Scope. The webcam operates on the other USBs just fine.

Option 1:
- Find a way to make either device operational on a different USB
Question 1 – How would I do this?

Option 2:
- Use a USB hub at the scope to plug the 500D, EQ6 and webcam into,
and then just have one USB cable from the mount to the netbook

Question 2 – Can the relevant data travel down one USB cable via a hub? If this can work, it is certainly a tidier option than running 3 cables between mount and netbook


I visited Jaycar today and they have a 5m Active USB 2 Repeater cable $40. They also had a 10m Active USB 2 Repeater cable with 4 port hub at one end for $25, same brand and specs. This seems odd to be cheaper. Then there’s the USB extenders designed for Cat5 cable (up to 80m – overkill for me) for $100.

Any thoughts welcome,
Bruce

[RobF]

Hi Bruce

It is possible, but you're pushing things and probably best to carefully add devices one at a time to check everything is playing happily. I routinely run an Orion Starshoot autoguider, HEQ5 and FCUSB off a single unpowered hub on the end of a 10m active usb extender cable from Jaycar. I used to also run my Canon 450D on the 4th hub slot with no problems (which frankly surprised me!).

[BC]

Thanks Rob,

That's interesting. I was surprised to see a 10m unit when all the doco I have read says that 5m is the maximum. Did you ever get the live view on the 450D to work at the computer over that distance?

Bruce

[mithrandir]

Bruce, try unplugging the cable you are using for StellariumScope, uninstalling the drivers, and plugging it into another port.

You may have to select "Show hidden devices" in Device Manager to find the cable definition when it is unplugged. Make sure you remove every instance.

You didn't say which version of Windows it is, or what brand of cable it is, but getting USB drivers working on multiple ports is hard work since a lot of manufacturers don't write smart drivers.

Once you have it working label each device and the corresponding port so you can always connect them the same way.

[BC]

Thanks Andrew,

It's Windows XP and an unknown cable brand.

Having spent hours yesterday getting Stellarium Scope working properly, I might not rush to play with port drivers, since I'm not that good at some of this stuff, but it's helpful to know what to do next when I'm feeling game. It's also good to know that it's common to work on only 1 port.

Bruce

[RobF]

Yes - that's how I focused for the venus transit last month.
5m is the limit for passive USB, but I believe there are chips in the active cables to keep the timings ok. Have read about people chaining 2x10m, but not somthing I need to do, so don't tempt fate.

[mithrandir]

Lindy claim up to 56m and 480Mb/sec with their active USB systems. You need fairly deep pockets. Lots of cheaper extenders up to 30m on ebay.

[Colin_Fraser]

Hello Bruce,
cable distance is one issue but the current drawn from the USB port is another problem.
Some laptops may have 3 or 4 USB ports but only one might supply 500ma.
The other ports may only be 100ma. That is why some devices work on selected ports only.
Desktop computers are similar. The USB ports on the back of the tower supply more current than the USB ports on the front (historically).
Advice others have given is correct, get a decent powered USB hub.

[2stroke]

Or get something with USB3 and have 900ma :) But yer the power hub solves that anyhow.