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Thunderbolt dock with dual DVI out?

J

jdechko

macrumors 601
Jul 1, 2004
4,230
325
Due to the way that Thunderbolt works, it's highly unlikely that you'll find a single device with 2 DVI ports out. Thunderbolt carries the thunderbolt data signal plus one DisplayPort Signal. The manufacturers would need to include another "thunderbolt device" internally to peel off the second DP signal.
 
M

manu chao

macrumors 604
Jul 30, 2003
7,219
3,031
jdechko said:
Due to the way that Thunderbolt works, it's highly unlikely that you'll find a single device with 2 DVI ports out. Thunderbolt carries the thunderbolt data signal plus one DisplayPort Signal. The manufacturers would need to include another "thunderbolt device" internally to peel off the second DP signal.
Click to expand...

How come Apple's TB display then allows two of them to be driven by one TB port?
 
J

jdechko

macrumors 601
Jul 1, 2004
4,230
325
manu chao said:
How come Apple's TB display then allows two of them to be driven by one TB port?
Click to expand...

Think of thunderbolt as a recursive technology. That is: Thunderbolt is Thunderbolt + DisplayPort. So TB also is ((TB + DP) + DP) and so on.

The Apple Thunderbolt display separates (de-muxes) the display port signal from the thunderbolt signal (which, as I mentioned above, is a combination of the 2 signals itself). The display port signal is used to drive the TB display, while a clean TB signal (containing it's own display port signal) is passed along to the second monitor.

Because of the way the signal is constructed, it allows for daisy chaining in multiple configurations. You could have Mac - TBDisplay - TBDisplay - External Hub or you could have Mac - External Hub - TBD - TBD or Mac - TBD - ExternalHub - TBD.

However, each thunderbolt device only gets access to one display port signal, which is why it's not possible to have a single dock with dual video outputs. That's why hubs like the CalDigit, even though they have multiple video outputs, can only use 1 at a time. Either the HDMI or DVI port gets the signal.
 
M

manu chao

macrumors 604
Jul 30, 2003
7,219
3,031
jdechko said:
Think of thunderbolt as a recursive technology. That is: Thunderbolt is Thunderbolt + DisplayPort. So TB also is ((TB + DP) + DP) and so on.

The Apple Thunderbolt display separates (de-muxes) the display port signal from the thunderbolt signal (which, as I mentioned above, is a combination of the 2 signals itself). The display port signal is used to drive the TB display, while a clean TB signal (containing it's own display port signal) is passed along to the second monitor.

Because of the way the signal is constructed, it allows for daisy chaining in multiple configurations. You could have Mac - TBDisplay - TBDisplay - External Hub or you could have Mac - External Hub - TBD - TBD or Mac - TBD - ExternalHub - TBD.

However, each thunderbolt device only gets access to one display port signal, which is why it's not possible to have a single dock with dual video outputs. That's why hubs like the CalDigit, even though they have multiple video outputs, can only use 1 at a time. Either the HDMI or DVI port gets the signal.
Click to expand...

Thanks, I've got the same answer in another thread. What I am curious is whether one could use the TB-out port of docks for a display if one keeps the direct video ports of the dock unused? This essentially an academic question as the only reason to do so would be the not needing an HDMI->mDP adaptor.
 
C

ColdCase

macrumors 68040
Feb 10, 2008
3,360
276
NH
manu chao said:
Thanks, I've got the same answer in another thread. What I am curious is whether one could use the TB-out port of docks for a display if one keeps the direct video ports of the dock unused? This essentially an academic question as the only reason to do so would be the not needing an HDMI->mDP adaptor.
Click to expand...

For dual-display to a single computer TB port, with the StarTech Docking Station you can connect one HDMI monitor and one Thunderbolt monitor simultaneously. Note one monitor must be a Thunderbolt monitor. When the dock is connected to a DisplayPort monitor the HDMI will be disabled. I think most docks work this way.
 
J

jdechko

macrumors 601
Jul 1, 2004
4,230
325
manu chao said:
Thanks, I've got the same answer in another thread. What I am curious is whether one could use the TB-out port of docks for a display if one keeps the direct video ports of the dock unused? This essentially an academic question as the only reason to do so would be the not needing an HDMI->mDP adaptor.
Click to expand...

Yes. As far as I'm aware, you could use the Thunderbolt port on a docking station to drive a non-thunderbolt display if the other video ports are unused.
 
P

paulrbeers

macrumors 68040
Dec 17, 2009
3,963
123
manu chao said:
Thanks, I've got the same answer in another thread. What I am curious is whether one could use the TB-out port of docks for a display if one keeps the direct video ports of the dock unused? This essentially an academic question as the only reason to do so would be the not needing an HDMI->mDP adaptor.
Click to expand...

You have a couple of options to use two displays off of the "thunderbolt port"...

1. buy two docks with HDMI or DVI in each one and daisy chain the two docks.
Mac -> Dock1 -> Dock2 with each dock having a monitor plugged into it.
2. Buy one dock + some other Thunderbolt device + MDP dongle
Mac -> Dock* -> Other Thunderbolt Device -> MDP Dongle -> Monitor 2
*Monitor 1 is plugged into the dock
 
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