Structure and topology

USB uses a tree topology and is host-controlled. That means that a PC with host functionality is mandatory for using USB. Therefore, it is not possible to directly connect two USB devices (with the exception of USB on-the-go compliant devices). Neither is it possible to connect a camera to a PDA device.

Theoretically, 127 devices can be connected to a host controller. Using external hubs or repeaters, even more devices can be connected, and from a greater distance. Provided that a maximum of 5 hubs/repeaters may be daisy-chained, USB devices can be connected in up to seven levels.

Fig. 69: USB topology

Hinweis

The maximum bandwidth of 480 Mbit/s per USB 2.0 host or 400 MByte/s per USB 3.0 host cannot be exceeded. Therefore, the maximum possible frame rate will be reduced if image data from multiple USB cameras is transferred simultaneously.

The available bandwidth might also be decreased when you use hubs or repeaters. You can reduce the bandwidth required for each camera by lowering the frame rate or the image size.

Suggestion for improvement? Send us your short Feedback on this chapter. Thank you very much!

For technical questions please contact you local distributor or use the support form on our website.

Home > A: Camera basics > USB interface >	History back Previous chapter Next chapter Print
Structure and topology