Question Issues with USB3 hub chained from Thunderbolt dock ?

[jauntysquirrel]

Hi all,

I am using a Corsair TBT200 thunderbolt dock connected to my M2 Macbook Pro running Ventura. For some USB A devices I have, I connected a TP-Link UH720 hub to one of the TBT200's USB A ports (I have more USB A devices than the TBT200 has ports for). The weird thing is that only 3 of the 7 ports on the TP-Link hub work.

For more context:

1. I have the TP-Link hub connected to AC power adapter, so it shouldn't be overdrawing power from the TBT200.
2. The other 4 ports on the TBT200 *do* seem to supply power to a connected device, but no data connection/the device is not seen by the computer
3. System Information > Hardware > USB seems to show the TP-Link as a "4-port" hub. Again, only 3 of the ports actually seem to work fully
4. It is 3 specific ports on the TP-Link hub that work (presumably the "first" three?) i.e. I can't use *any* three, only three specific ones.
5. TP-Link hub works fine on its own with all ports working as expected.

It would *greatly* simplify my set up if I could use more of the ports on the TP-link for low-bandwidth peripherals, so I'm trying to see if this is an issue that can be fixed. If it really is just an unavoidable consequence of trying to chain these things, I can deal with it and try to work around. But I haven't seen a clear reason why yet so still hoping there is a solution. Let me know if more info would help. Thanks in advance for any insights or suggestions!

 

[Ralston18]

Connectivity being:

M2 Macbook Pro < ----->[ Port ?] Corsair TBT200 thunderbolt dock [USB A port] <-----> [USB port X] TP Link UH700 [ USB ports] <------> other USB devices.

Feel free to edit and correct my line diagram as necessary. Or create your own diagram to show all devices and connections.

This TBT200?

https://www.corsair.com/us/en/p/hubs-docks/cu-9000002-na/tbt200-thunderbolt-4-dock-cu-9000002-na

This TP-Link UH720 hub with 7 ports?

https://www.tp-link.com/us/home-networking/usb-hub/uh720/

Were there any Thunderbolt software/drivers downloaded?

Reference:

https://www.corsair.com/us/en/p/hub...hunderbolt-4-dock-cu-9000002-na#tab-downloads

 

[jauntysquirrel]

Thanks for the reply!

Re: connectivity, yes that's the idea. Here with a little bit more detail

M2 Macbook Pro [TB4] < ----->[Front TB4 host port w/ charging] Corsair TBT200 thunderbolt dock [Rear USB A Superspeed port] <-----> [Host USB port] TP Link UH700 [ USB ports] <------> other USB devices (e.g. mouse, keyboard, low-power mic-preamp for dictation mic, low-power midi devices etc.)

Re: hardware
Yes, that is the correct TBT200 and the correct TP-Link UH720 hub

Re: drivers
I did install the Tunderbolt utility from Corsair as specified here: https://help.corsair.com/hc/en-us/a...0-How-to-Install-the-Thunderbolt-Dock-Utility
(I installed v1.5.2)

 

[Paperdoc]

A Few thoughts.

1. Do you have the power supply module of the Corsair TBT200 connected?
2. Are there any configuration options in the TBT200 drivers etc. to limit which ports are active? OR to specify what data rate each port uses? (Normally, any such port (like the Type A Superspeed ports) should negotiate a data rate with any device connected.)
3. Have you tried plugging the TPLink UH720 unit into different Superspeed ports of the TBT200?
4. Any possibility the UH720 unit is faulty even though it can work properly when NOT connected to the TBT200?

 

[jauntysquirrel]

Thanks Paperdoc. Looking through your suggestions and trying a couple things I think I figured it out!

Short version is, if I plug the UH720 into the *front* USB A port on the TBT200 it works as expected.

Longer version based on inspecting the MacOS system information window: It looks like may be an issue of USB chain depth. It seems the TBT200 considers it's front USB A port a top level port of its hub, and it considers the back 2 ports as a secondary "hub" connected to it's primary hub. Then, the UH720 considers it's first 3 ports top level ports, and it's second 4 ports as a secondary "hub". So all in all, connecting the UH720 to the back of the TBT200 creates one more effective layer of chain depth, which I'm guessing is the reason the UH720's last 4 ports aren't seen properly?

It's a bit ergonomically annoying to have to use the front port (hoping to keep that for thumb drives and such) but at least I'll have enough USB ports! And I learned a bit more about USB chaining in the process

Thanks again!

 

[Paperdoc]

"Learned a bit more ..." - Me Too! I have never encountered this detail in USB chaining. I just assumed the chains had almost unlimited depth, I guess. Now I'm thinking about why?, and I have a SPECULATION - definitely not a fact. As a system boots, every device goes though an initialization process. One aspect of that often is that it inquires all subsidiary devices to verify that they are working properly before relying on them. Of course, there is a time-out limit on how long they will wait for a positive result from a downstream device. So MAYBE if the chain is too long, the last device cannot complete its initialization and reply properly before the first device times out. The the last device might not be recognized.

Irrespective of the real cause, it is very useful for all of us here to learn this limit. Thanks for telling us. And thanks for Solution.