It seems hard to make USB printers and computers talk reliably. I have two printers variously connected to two computers, all USB v2, and find only certain USB cables work (the computer reports them being offline). They won’t work at all through a new USB hub (a powered one with its own power supply), though the scanner will. Thumb drives won’t work through the hub either. With certain cables and no hub, all these things work fine. At most I have been trying to connect three USB devices, though I would like to be able to use more.
What tricks are there to keeping USB working? I know about unpowered hubs and current draw, and I’m not committing that offense. There should also be some kind of slowing down if you have many USB devices all trying to transfer data simultaneously, I guess, but we’re not there. What else?
In general, using powered USB hubs, should you be able to connect any USB device?
USB hubs sometimes just die in a weird way that means they might recognise there is a device attached, but fail to be able to talk to it properly. In my experience, powered hubs tend to have a shorter working life than bus-powered ones. Maybe I just bought too cheap though.
One thing you can try is to remove phantom USB entries from the device manager - following the instructions here: http://support.microsoft.com/kb/241257
Once you’ve got device manager showing all the non-present devices per those instructions (NB: which is not the same as just clicking ‘show hidden devices’), you can just delete all of the USB stuff - devices, root hubs, the lot, then get it to scan for new devices and install them agaiin.
Might work - sometimes the huge mess of device entries just fouls up the normal operation of Windows.
There’s no trick at all. A data connection is established and the computer talks to the device. I suspect you either have a bad hub or that you will need to reinstall the printer drivers.
Everytime you move the USB plug to a different port you can break the existing printer connection and sometimes a reinstall of the drivers is required. Typically, windows does this automatically, but that’s not always the case. So if you’re always switching around to different ports and hubs then the computer is sitting there confused.
You aren’t trying to use particularly long cables are you? With most communication protocols, you can use longer cables than you’re supposed to, but with USB it really can cause problems.