Last updated: 23 February 2005
Subject: DSI / LPI USB Power Levels Affecting Operation / Drivers Loading Sent: Wednesday, February 23, 2005 07:05:40 From: Stephen Bird (firstname.lastname@example.org) I noticed that there had been some concern over USB power levels, in particular for the DSI and one person had noted the issue of powered and non powered hubs. I had a play with both the LPI and DSI on my 3 PC's, and noted that the LPI really does not care which port, USB1 or 2 is used and whether a powered hub, non powered, or fixed port on the PC is used. The DSI is a different story. On some PC's with a number of integral USB ports, if one or more other devices drawing power from the USB card are connected (such as my DSL modem drawing 500mA), then the DSI is not registered as being detected or gives an error message as the connection is attempted by the Imaging software, (the error message is a long series of computer gibberish about failed strings and the like). Worse than that if you try to install the Autostar Suite and then the DSI, it cannot see the DSI when you try to install the driver so the installation fails. As I said the LPI loads just fine with my PC's on the same USB ports so I assume it draws far less power. Then with the same PC, but via a powered hub, the DSI loads its driver and works fine every time. With Windows XP, two drivers are loaded for the DSI, what you see is the driver part of the installation run twice, one is the Meade DSI Driver, the other is something called EZ USB or similar name. And just to cause a little more surprise, if you remove all the power sapping devices, or use a USB port on another discreet USB card in the same PC, again the DSI will work just fine. I even have problems with the front mounted port on a desktop, which is part of an array of ports for USB, firewire and camera cards various. I can only think that this port has a limited power supply that cannot power the DSI. The ports at the back of this PC are fine, probably on a separate card with its own supply internally?? So another suggestion for people having problems getting DSI (or LPI) drivers to load, is to use a powered hub, and or, disconnect other USB devices so that the DSI (or LPI) gets its full share of the USB power. I have found that with XP, allowing this full availability of power gets round the previous anomaly I saw of having to point the PC at the exact location of the DSI / LPI drivers, I can now get them to consistently load as per the Meade instructions every time. This does not work for my Windows 2000 Laptop however, this still requires me to point the PC at the location of the drivers on the hard disk when loading the Autostar Suite for the first time. Afraid I haven't been able to test this with Windows 98SE as I upgraded that PC to XP when I got the DSI, but it might be worth someone trying the USB powered hub to see if it helps those with problems on that platform. So to summarise, if you have driver of DSI operation problems, use a powered hub, of disconnect other USB devices to see if that solves it. If do then it could be a USB power problem. Maybe Meade should state the power draw of the DSI and fit it with an external supply connection for difficult situations. Regards Stephen Bird
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