Pixelink's PL-D cameras may exhibit certain connection issues when connected to a USB 2.0 port. Some of the known symptoms are provided below.

1) When connected to a USB 2.0 port with an autofocus lens, the camera's LED may be orange at first, blink green light for 1 second, and then return to orange once again and fail to start up.

2) On certain computers (particularly older systems), PL-D cameras may not show up in the device manager, or may crash while streaming.

Reason for failure:

This type of problem will only arise if the camera does not receive suitable amount of power from the USB 2.0 port. On certain hosts, a camera without an autofocus lens would be recognized in the Device Manager when connected to a USB 2.0 port, but lose connection from the host when the camera starts streaming. Alternatively, some cameras with a Varioptic autofocus lens may never seem to power up properly. These are symptoms of the camera not receiving sufficient power.

A USB 2.0 port can only output 500 mA compared to an USB 3.0 port, which can provide 900 mA. A shared USB 2.0 bus may, however, be able to provide more power than 500 mA, and therefore some PL-D cameras are able to run properly in some USB2.0 ports.

An idle camera will require less power than a camera that is streaming. So at first, when a camera is connected to the port and recognized by the host, as it will not draw as much power until it starts to stream. If the camera cannot draw enough power for its operation, it will get disconnected from the host or crash the program. And as an autofocus lens from Varioptic requires 10-20 mA of power for its operation, a PL-D autofocus camera may not be able to start if it receives insufficient power for both the camera and lens. 

For guaranteed performance, Pixelink recommends using PL-D cameras with a USB 3.0 port, which can supply more power than a USB 2.0 port.

If, however, a USB 3.0 port is not available, the camera can also be connected through an externally powered USB hub, to ensure the camera receives sufficient power.