USM3 cable length limits

Discussion about the UCH, our industrial grade, smart USB3 Hub
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Bryan
Posts: 12
Joined: Sat Apr 03, 2021 12:17 am

USM3 cable length limits

Post by Bryan »

I have a 36 MP QHY CMOS camera with USB 3 output. My preferred route is for the camera output to go to the USB Control Hub (UCH) as it eliminates one USB cable through the mount.

Routing the camera output via a 1m USB3 cable to the UCH, then a 1m cable to a powered USB 3 hub, and finally a 5m USB extender cable to the PC does not work. The same connection on a 15 MP CMOS camera (USB3) is fine; so I assume the data rate is the issue.

If I run the 1m cable from the camera directly to the powered USB3 hub and bypass the UCH, then the 5M cable to the PC DOES work.

I thought that even USB3 was not limited in length, IF connected via a powered hub.

Is this incorrect or should I be looking in other settings or cable arrangement for a solution?

Bryan
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Evans
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Re: USM3 cable length limits

Post by Evans »

USB3 protocol has a max cable limit of 3meters.
Some devices have a transciever that might work at longer cables but as you exceed the 3meter limit there is no guarantee that it will wok stable and flawlesly.

For more information please check here: https://pegasusastro.com/cable-manageme ... phy-setup/
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Bryan
Posts: 12
Joined: Sat Apr 03, 2021 12:17 am

Re: USM3 cable length limits

Post by Bryan »

I have seen that table already on the PegasusAstro cable management page...https://pegasusastro.com/cable-manageme ... phy-setup/... The sections following the table discuss cable extenders and powered hubs for USB3. While not explicitly stated, does the use of a powered USB hub NOT change the USB3 maximum of 3m? In an observatory situation, this is a severe limit.

This does not make sense, because my setup does work with a 1m USB3 from camera to powered hub, followed by a 5m cable. What makes it fail is the addition of the UCH and an additional 1m cable from the UCH to the hub.

Bryan
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