USB Hub connections

[Fay]

I would like to do all my USB connections through one hub, as there are so many.

I have tried a couple of camera's, but they are not recognised, I thought it may only apply to one, but it looks like it will not be accepting anything just like that.

I plugged the webcam into the hub & the fan sounds a lot more ferocious & noisy than when it is plugged direct into the laptop. Does anyone know why this is ?

Also is there an easy way to re asign everything via the hub or will it be a battle?

Thanks     

[Rick]

I've found that not all USB hubs are equal, and that cameras in particular can be very fussy about their connections. Oh, and my limited experience of USB and Windows suggests that you'll probably be asked to re-install the drivers every time you change the physical socket you plug the device into...

[Mike]

You need to be careful with Hubs too as they may introduce electrical noise into your imaging train. You'll only be able to tell by doing side by side comparison images.

[mickw]

I think Robert went through hell trying to sort his hub out 

He should be able to help you avoid any pitfalls, or at least steer you in the right direction.

[Ian]

and just to continue the hub bashing the USB spec includes providing up to 500mA at 5V to power devices. Straightforward webcams fall into this category. However, the PC is only capable of supplying, if you're lucky, 500mA to one device. If you put a hub in, it'd be merrily consuming a chunk of that 500mA leaving a good deal less for anything after it. This is why the majority of hubs have a small power jack to take an external supply. The hub will then be able to supply 500mA to each downstream port.

In my experience, you will get away with usb to serial adaptors, mice, keyboards and so on without too much difficulty. I would give a webcam it's own port. The main imaging camera will have it's own power supply so should be ok.

The other thing to note is bus bandwidth. That is, how much data can be passed on any one port. A webcam, if it's USB 1.1, will use all available bandwidth when imaging a video stream. If you plan on running anything else plugged into the same port on the laptop, expect dropped frames and connection issues if bandwidth becomes saturated.

And another thing. If you plug a USB 1.1 device into a USB 2 port, the laptop port will have to slow down to 1.1 speeds. For *all devices* on the port.

In short, consider the power requirements, if it moves, makes a noise, has lights or gets warm, expect it to need it's own port, or a powered hub.
If it's moving lots of data around, give it a laptop port to itself.
Keep v1.1 devices off the bus if there's a v2 device moving lots of data around (thumbdrives, cameras and so on)

I promise not to mention the fact that some laptops may have two or more usb ports, but internally they may be on the same bus.

[Fay]

B......y hell!!!!

Thanks for all that, lot to think about

[Ian]

sorry, that was a bit of a brain dump, wasn't it. 

[Fay]

It has to be told as it is, Ian.

The trouble is, when I am slewing etc etc, I have to pick my table up, with the laptop, & walk around until the mount stops. By then about 15 cables are all wrapped around everywhere, this includes cables that are not connected to USB.

If there was only, one. it would be so much easier.

[Mac]

Fay dont bother with a hub, far too much hastle.
go for one of these.

http://www.maplin.co.uk/Module.aspx?ModuleNo=47100  or 
http://www.amazon.co.uk/USB-PCMCIA-Port-Expansion-Card/dp/B000PIZTB2/ref=sr_1_16?ie=UTF8&s=electronics&qid=1238077076&sr=8-16

you will probably find the amazon one dosent come with a power supply, thats why its only a fiver..

Asuming you have a pcmcia card slot on the side of your laptop.
it has a power socket on the card, so any devices that need to be powered can be.
Just by pluging the power supply in to the card.
Other devices just toodle along with out any problems,
I have my H9 pluged in to this normally.

It gives you four High speed usb2 ports, and allows you to run them all at full speed.
No bottlenecks.

I use these. (shameless plug there), but i have the 2 port belkin as my laptop already has 4 usb ports anyway.

If your having to move the laptop to stop the camles from tugging how about getting extensions.
http://www.maplin.co.uk/Module.aspx?ModuleNo=97266

Mac.

[Fay]

Mac, I do use one of those cards, sometimes.

If I used this setup:

                   USB
Canon            2
Shoestring      1
Webcam/guide 2
Robo              1
PCMCIA Card   1

I need 7 USB ports. The laptop has 4.

I do have enough ports on the laptop, sometimes don't need the card.

I was thinking, as well, while I do not have another laptop for Develo, I could run a USB cable indoors, so could sit in warm if too cold outside, with the laptop, but could only do that if I put an extension on the one USB connection. Does that all make sense, I could be rambling!! 

[Ian]

I'd bundle the cables up and make a loom, like I described in one of Caroles threads. Then you can have any number of cables, but look after them together.

[Fay]

Where have you explained that, Ian?

[Ian]

this post:

http://forum.orpington-astronomy.org.uk/index.php?topic=4452.msg23909#msg23909

[Mac]

I could run a USB cable indoors, so could sit in warm if too cold outside

why not run a network cable to the laptop, and sit at your desktop controlling it from there.
using remote access.

so much easier..

[Fay]

It is too far away.

I do not want to use the connection via the mains unless I get a new laptop, as I do all my finances on the desktop & do not want any risks.