ASIAIR USB 3.0 Problem

TecMar

Hello,

my asiair plus runs with a 533MC Pro in FULLHD video mode on USB 3.0 without any problems, if I use a 178MC instead of the 533mc, the camera hangs and the FPS drop, and the Asiair says that the camera is no longer connected.

However, if I connect the camera to USB 2.0, it runs without any problems

Walf@ZWO

Is the exposure time of 178mc same between usb 2.0 and 3.0？

TecMar

Dont't know why but works..

DonAL

Recently purchased the ASI585MC, ASI2600MC and ASIAir Plus. When either or both cameras are connected to the ASIAir USB3 ports, the "Exposure Failure" message is consistently seen but a random number of camera exposures could be captured after a system reset. To isolate the error message root cause, the cameras were connected to a laptop and operated via ASIStudio; the cameras (imagers) worked fine. Suspecting an issue with the ASIAir, each camera was again connected to the USB3 ports and resulted in the same intermittent error message. Each camera was then moved one at a time to an ASIAir USB2 port; each camera worked fine and without the error message. My concern with the ASIAir is that its USB3 interface has a buffering problem when moving data from the cameras. Thoughts?

w7ay

DonAL Thoughts?

It is not likely to be a firmware problem. I have 4 different versions of ASIAIR, and they all work with USB 3 devices (I use USB hubs in all cases).

Try removing all USB 2 and 3 devices from the ASIAIR. Connect a powered USB hub to only one USB 3.1 port of the ASIAIR, using a USB cable that is no longer than 0.5 meters. 0.25 meter long cable would be good. Now connect all other devices to that USB hub.

If it works, you have won the ZWO USB lottery. I would ask for the ASIAIR to be replaced in any case, even if you are willing to keep using a USB hub.

USB 2.0 is a 4 pin interconnect. Two of the pins is a differential pair that handles the half-duplex data (both transmit and receive go throught the same pair, thus limiting the speed of the standard).

USB 3.1 added 5 more pins (you can see them in the Type-B connector's hump, and if you look deep into a blue USB Type-A connector, you will see those extra 5 pins).

One of the new pins is a ground drain (use to make sure the shield in the USB 3 cable is grounded). The other 4 wires form two differential pair of full duplex data (one pair for transmit , and one pair for receive).

When the USB 3 connector is first plugged in, the device first handshakes with the computer through the USB 2 interface to tell the computer end that it is USB 3 capable. If the computer finds that it is USB 3 capable, it switches to using the full duplex for data.

The sin(x)/x spectrum of the USB 3.1 data extends all the way to 5 GHz, and PC board layouts for USB 3 must be able to handle the data signal as an RF signal with nicely controlled impedances (i.e., pretty much using micro-stripline techniques, or with PC board traces no longer than 1/4 to 1/2 of a wavelength at 5 GHz [1.5 cm to 3 cm] between the USB connector and the USB chip). If the PC board is willy-nilly laid out as if it is carrying lower frequency signals, that port will fail to transfer data properly when cable impedance changes, cable length changes, etc.

Some short data commands will go through, but once massive amounts of data are transferred, some will eventually fail if the PC board layout is poorly designed, and/or not have the required engineering margins.

Chen