224Alvium USB Cameras User Guide V3.6.4
Performance and troubleshooting
Cascading hubs divide bandwidth
The following example applies to standard behavior without individual settings.
The graphics show bandwidth distribution on a common bus. Three cameras try to
use full bandwidth at the same time. If one camera is inactive, the host will provide
its share to the others until this camera sends data again.
Using the U3 mode
If you want to pause camera operation, you can use the U3 mode to reduce the
power consumption of Alvium USB cameras to ~ 16 mA. In this section, you learn
to change between operational mode and U3 mode by
DevicePowerSavingMode
and host or backend commands.
The
DevicePowerSavingMode feature selects between standard power use and
various power saving modes, avoiding unexpected camera behavior:
Figure 91: Bandwidth assignment for cascading hubs
Values
Table 112: Description
Disabled
The camera uses standard power (default).
SuspendMode
The camera is enabled to go into to USB U3 power saving
mode.
1
Table 113: Options for DevicePowerSavingMode
Please observe
• To operate the camera again after using U3 mode, the camera reboots itself.
After reboot, all camera settings are reset to default values,
DevicePowerSavingMode is reset to Default.
• The U3 mode is not supported for USB 2.x connections.
Host
adapter
card
Hub 01
Hub 02
Camera 01
Camera 02
Camera 03
100% 50%
50%
25%
25%
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