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Alvium USB Cameras User Guide V3.6.4
Performance and troubleshooting
Dividing bandwidth between devices on a
common USB 3.0 or 3.1 Gen 1 bus
Ideal setup for two cameras
Preconditions
• Control traffic is ignored.
• The possibility of the host being busy with other tasks is ignored.
• Cameras share 100 percent bus bandwidth.
• Cameras need 100 percent bus bandwidth in total.
• Cameras stream in the same way because they are the same model and have
identical settings.
• No other device is connected.
Result
• Bandwidth is divided by two, cameras get assigned 50 percent bandwidth
each.
For three cameras, the bandwidth is 33.3 percent each.
• If one camera sends no data, the other camera will be assigned 100 percent
bandwidth. To always assign 50 percent to both cameras, they have to be
controlled to use no more than 50 percent bandwidth each.
• If the computer cannot process the images received from a camera, images are
corrupted.
Best practice for bandwidth management
• To assign maximum bandwidth to a camera, make sure your camera is the only
device on the bus.
• Avoid devices, such as a monitor or a mouse, sharing bandwidth with the USB
camera connected to the same bus.
• For maximum bandwidth, use a current version host controller card.
See the Alvium Cameras Accessory Guide at
www.alliedvision.com/en/support/technical-documentation/
.
• USB3 Vision devices use bulk transfer. Avoid using other transfer modes.
• Control bandwidth by assigning the desired amount to the separate cameras.
