Why no Thunderbolt hubs?

Jeff Charles · Dec 3, 2012

A simple Thunderbolt hub, with 3 or 4 TB ports, would be useful, but none are available. I wonder why.

For example: I want to connect 2 non-TB displays and a FW 800 drive to my Macbook Air, but it only has one TB port.

Jeff

flynz4 · Dec 3, 2012

TB use a "chain" of devices. You will need to look for devices that have dual ports... so that you can pass-through the TB signal. In your cases... you want to connect three different devices that would be at the end of the chain.

/Jim

Jeff Charles · Dec 4, 2012

flynz4 said:
TB use a "chain" of devices. You will need to look for devices that have dual ports... so that you can pass-through the TB signal. In your cases... you want to connect three different devices that would be at the end of the chain.

/Jim

Thanks. I understand how TB works, but I have two non-TB displays that I cannot daisy chain. I'd have to replace both, in order to connect my FW 800 drives at the end of the chain.

Back to my original question: Why are there no simple TB hubs available? Technical reasons? Legal reasons?

Jeff

justperry · Dec 4, 2012

Jeff Charles said:
Thanks. I understand how TB works, but I have two non-TB displays that I cannot daisy chain. I'd have to replace both, in order to connect my FW 800 drives at the end of the chain.

Back to my original question: Why are there no simple TB hubs available? Technical reasons? Legal reasons?

Jeff

I think for technical reasons it is 2 Maximum, you most likely can not make a "T Junction"
I think you could make one with any number of ports but only two can be active.

Jeff Charles · Dec 4, 2012

justperry said:
I think for technical reasons it is 2 Maximum, you most likely can not make a "T Junction"
I think you could make one with any number of ports but only two can be active.

That may be the answer, but why couldn't multiple TB ports be daisy chained inside a hub?

Macman45 · Dec 4, 2012

I think your answer lies more in the licensing of the technology, rather than for any technical reason..In other words it's perfectly possible, just hasn't been done. I'm fortunate to have a Pegasus R4 at the start of my " chain" and it has a passthrough TB port available too. If there were more products besides displays and mass storage devices available, then I think we'd see hubs for sale quick smart.

Never owned a TB enabled monitor, but I have daisy chined another Promise unit to my existing R4 to move bulk files for a freind and that worked well.

justperry · Dec 4, 2012

Jeff Charles said:
That may be the answer, but why couldn't multiple TB ports be daisy chained inside a hub?

There are clever people on this site to explain this to you, probably protocol.
It is a shame if it is not possible, would make a great hub, with other ports like USB, SATA, VGA, HDMI and so on.
Still way too expensive for the "normal" consumer though.

Macman45 · Dec 4, 2012

justperry said:
There are clever people on this site to explain this to you, probably protocol.
It is a shame if it is not possible, would make a great hub, with other ports like USB, SATA, VGA, HDMI and so on.
Still way too expensive for the "normal" consumer though.

That's my point...They want to keep it in the "Premium" category for reasons best known to the industry. There is no technical reason I can think of that prevents production of a hub.

MCAsan · Dec 4, 2012

Note we did not have hubs for SCSI, PATA, or FW. Those plus thunderbolt use bus topology. With USB or ethernet, we see star topology. Note we originally had bus toplogy with ethernet if any of you are old enough to remember coaxial ethernet in the 80s.

So for now, thunderbolt devices either have a repeater (two ports and be anywhere on the bus) or no repeater (one port) and meant to be the end of the bus.

flynz4 · Dec 4, 2012

MCAsan said:
Note we did not have hubs for SCSI, PATA, or FW. Those plus thunderbolt use bus topology. With USB or ethernet, we see star topology. Note we originally had bus toplogy with ethernet if any of you are old enough to remember coaxial ethernet in the 80s.

So for now, thunderbolt devices either have a repeater (two ports and be anywhere on the bus) or no repeater (one port) and meant to be the end of the bus.

Actually... USB uses a "tree" topology.

In any case... as you and both said (in different ways)... the chain topology (or as you state using repeaters)... TB does not support fan-out. It supports chains. If you buy devices that only have one port... then it must be at the end of the chain.

This is similar (in concept) to the original parallel SCSI bus where you could daisy chain up to 7 peripherals. Many SCSI peripherals that had dual ports could be part of the chain. SCSI devices with only a single port need to be at the end of the chain.

To the OP. If you want to use multiple devices... you will need to upgrade your peripherals to those that use dual ports.

/Jim

Jeff Charles · Dec 4, 2012

flynz4 said:
To the OP. If you want to use multiple devices... you will need to upgrade your peripherals to those that use dual ports.

/Jim

Thanks to you and to the others who responded to my OP. I understand now how TB needs to be configured. It seems very limiting for those who want to hook up multiple non-TB peripherals, especially considering that a TB port is multi-use.

There may be an alternative using one of the docking stations that's coming on the market. The Landing Zone Docking Station is one that I have been looking at, but the current version does not support two monitors, and it does not have a FW 800 port. They did tell me that their next version, which is to be released this month, will have USB 3.0 ports, but I don't know if it will support multiple monitors or FW 800. Also, the current model has only the one TB port for connecting to the computer.

Belkin's upcoming Thunderbolt Express Dock is a little better, because it has a FW 800 port, and an "output" TB port.

Jeff

hallux · Dec 4, 2012

Jeff,
Look at the Matrox DS1/DVI. It sounds like you want to use the Apple adapters for connecting to external displays, this has a DVI output AND a TB daisy-chain port. Keep in mind though, the TB port on Macs isn't a pure TB port, it's a combo TB and Mini-DP, and I believe the display adapters are actually Mini-DP. The external device would need to support mini-DP pass-through to the TB daisy-chain port to use the Apple adapters.

Jeff Charles · Dec 4, 2012

hallux said:
Jeff,
Look at the Matrox DS1/DVI. It sounds like you want to use the Apple adapters for connecting to external displays, this has a DVI output AND a TB daisy-chain port. Keep in mind though, the TB port on Macs isn't a pure TB port, it's a combo TB and Mini-DP, and I believe the display adapters are actually Mini-DP. The external device would need to support mini-DP pass-through to the TB daisy-chain port to use the Apple adapters.

Unfortunately, the Matrox does not have a TB daisy-chain port. It needs to be the last device in the chain.

Realistically, until a better dock comes on the market, it looks like the only way to run two external non-TB displays from an Air, is to drive one of them with a USB 3.0 display adapter.

hallux · Dec 4, 2012

Jeff Charles said:
Unfortunately, the Matrox does not have a TB daisy-chain port. It needs to be the last device in the chain.

Sorry about that, missed that tidbit.

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