Usb Hubs And Usb Extenders; Controlling Multiple Usb Devices With Usb Hubs - Paramount Fitness ME II User Manual

Problem

USB Hubs and USB Extenders

To achieve reliable communications between a computer and a USB device, the USB 2.0 specification
states that the maximum cable length is about 16 feet (5 m). Longer cables introduce delays in the USB
communication and means the computer cannot reliably "talk to" the attached device.
The Paramount is supplied with a standard USB cable that is roughly 15 feet (4.6 m) long and will reliably
control the Paramount mount. Any other cable configuration can introduce unwanted behavior.
To control CCD cameras, Software Bisque strongly recommends using a dedicated 5m (16 ft.) USB cable
plugged directly into the camera's USB port and the computer's USB port. The two USB ports on the
Instrument Panel are part of a three port USB hub that is built into the MKS 5000 control system, and this
hub can introduce unwanted behavior for example, communication failures, unreliable downloads, or
artifacts on photos.
If you need a longer USB cable runs, Software Bisque strongly recommends using a USB extension solution
from Icron Technologies (http://www.icron.com). They are expensive, but they work.
Software Bisque has experimented with many inexpensive USB extenders and most of them just do not
work. Even worse, some work "some of the time" but often result in strange or unpredictable behavior.
After adding any USB extender to the Paramount, if you encounter any unusual behavior with the
Paramount or device connected to the USB ports on the Instrument Panel, please see "Troubleshooting
Communication Problems" below.

Controlling Multiple USB Devices with USB Hubs

Software Bisque cannot guarantee the Paramount will work with every possible USB/USB Hub/USB
Extension/USB Device configuration. The number of hardware permutations is virtually unlimited, and,
based on Software Bisque's experience, USB extenders and USB hubs, even "industrial grade" hubs, can
introduce communication problems.
For example, Software Bisque has encountered configurations where an "innocent looking" USB hub in
the chain of computer/Paramount/Apogee Instruments CCD camera not only caused artifacts on the CCD
photos, TheSkyX Professional Edition would lose communication when the camera download photos. No
USB hub, no problems.
In another observatory, two of the ports on a four-port "industrial-grade" hub began to fail, and the driver
would then terminate communications with the camera and focuser. Again, removing the hub and
connecting all devices directly to the computer's USB port solved the communication issue.
Solution
torque to lift heavy loads, tracking performance, and slewing,
may suffer when the payload is greatly out of balance.
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