usb overload?

[Horwig]

Finally got my sgl focuser up and running in the obsy. Works a dream standalone,

trouble is that when I have Nebulosity controlling my imaging camera, phd on the

guider, and sgl focuser, all running at the same time through the hub at the mount,

focuser stops responding, or is very sluggish.

Is this kind of thing an indication of too many things off the same usb, and

would running more than one usb straight off the crate change anything?

[malc-c]

Is the hub powered or simply relying on the USB power from the PC ? - If the latter then you'll limited to 500mA, so it could well be an load / voltage drop issue, especially if using long cables between hub and PC

[Horwig]

No it's a powered hub, also running my (illuminated) keyboard and mouse. Focuser is fine when Nebulosity and Phd aren't running. It sort of feels like conflicts, will play some more.

Huw

[Reggie]

try it with nebulosity running without PHD? If it behaves fine then it suggests there is an issue with PHD? Doesn't nebulosity do it's own guiding? can you use sharpcap or wxastrocapture as an alternative guiding app.

Would be useful to know what other kit you're running too, like which imaging camera, which guider, is it a usb2 or usb1 hub?

[NickK]

Think of USB like a water pipe where only one thing can go down it at one time. So if something big is sending alot of info or there's lots of things attempting to send stuff, the pipe backs up.. (it's behaviour differs from ethernet for the technically minded)

Now a USB "bus" is the right turn for our water pipe.

My mac has two USB ports (or two busses)

I use one USB port, connected to a 10M cable (two 5M active repeaters) which then connects into my USB hub attached to the mount. So this cable handles low level traffic - my ATIK 16ic guide cam, my filter wheel and the EQMOD mount device. So the idea is that small messages go down this (the 16IC is only 640x480 images so this is quite small).

The other USB port I connect, again using a seperate 10M cable (2x5M active repeaters) to just the ATIK 383L. This is the big transfer cable as the 383L will dominate the USB for a few seconds as it performs a transfer of 17MB per image.

By splitting this, the 383L doesn't cause a problem with the other devices of the other cable. Usually the USB controller on the laptop can handle multiple USB busses, however often the astronomy devices aren't as efficient or capable in working together.

[Horwig]

Had a play in anger last night, seems to be a power up sequence issue. If the arduino is connected up first, and the focus software launched before anything else at works faultlessly.

Huw