Hi All,
if you try to use a Logitech Tap Microsoft Teams Room with two 4K monitors connected via Hub (Table and Display), you will find that only ONE monitor receive the video signal, and the other one not.
Instead if you connect the two 4K display to the NUC directly, you do not have any issue.
This is a know behavior/issue of Table and Display Hub, if two 4K display are connected to the Display Hub, the firmware automatically block the outbound video signal to one of them.
The problem? Today display are always 4K!
I’ve found a very simple, cheap and efficient workaround: use an HDMI-to-DVI standard adapter to connect the Display Hub to the 4K Display.
This trick force the Display Hub to stop to “see” 4K Display and start to “see” only Full HD Display, and your Tap will start to work with Dual Display perfectly!
Hope this could help some of you.
Best. Luca
Luca Vitali [MVP] 
Would not this workaround affect the turn on and off of the TV? Just wondering..Nice website and great info! thanks!
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Hi Yesid, I’m sorry but no, this trick do not solve the very unpleasant on-off monitor issue. Best. Luca
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This may help. The issue is related to the bandwidth limitation between the Rally Hubs supporting one 4K display or two 1080p displays. Simple fix would be to change the display settings in Windows. This is documented on support.logitech.com. Make sure you go into Advanced settings per instructions. Also, contact Logitech support if you continue to have issues as they have other options to help.
https://support.logi.com/hc/en-us/articles/360025178394–FAQ-Rally-ConferenceCam-system
Cheers, B.
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Hi Brad, setting the two monitor resolution to Full HD in Windows do not solve the issue. If the Display Hub see a 4K monitor connected, this disable the second monitor, whatever resolution you set. I hope this will be corrected in future fw. Best. Luca
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Hi Luca,
Thanks for the post. Any idea how to update the firmware on Tap? We are having an issue with the screen keeps flickering between tap and the TV. Not sure if its a cable issue or firmware. Our current software build is 4.2.4.0 Provisioning version 8. Thank you
J
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To update the fw on a Logitech Tap you have to download and install the latest Logitech Sync Application from Logitech Download site https://support.logi.com, it will check for any Logitech product connected to the NUC and will update the fw. Best. Luca
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Luca,
Are you going HDMI to DVI to TV? Or HDM to DVI back to HDMI to TV?
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Hi Brett, HDMI to DVI to TV. This will break the 4K signaling and our Tap appreciated, enabling again the dual monitor 😉
Best
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Dang, My tv’s don’t have DVI.
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to confirm with your testing, if you hook the two tv’s directly to the nuc, it would work correctly as well? I may bypass the tablehub and display hub and order two hdmi over cat6 if that worked for you.
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Correct, the issue is bound to the hubs that lock the dual monitor if 4K signal is found. If you place the NUC under the monitors and connect the two monitors directly to the NUC, you will not have this problem
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Luca – nice post, and thanks for helping the community!
As Brad mentioned, it is supported (and does work) to set the displays to 1080p. Keep in mind Windows 10 will try to upscale to whatever TV type is detected, so 1080p must be set in advanced settings of the display adapter properties. This can also be done automatically by installing the multi display tool at https://github.com/youseeadam/Logi-Multi-Display-Utility.
There may be some scenarios with some TVs in which the NUC HDMI (or thunderbolt 3) display output is asleep (no HDMI sync) and the TV is awake – this creates a scenario in which Rally detects a 4K signal and disables the 2nd HDMI port. The workaround you described will work great, as long as the DVI adapter is not dual link DVI with 4K.
For those of you with just HDMI, there is a solution! You can purchase an EDID emulator that does the same thing. an example at https://www.amazon.com/Pass-Through-splitters-Extenders-fit-Headless-3840×2160/dp/B07C8BHPD6?th=1. Keep in mind Logitech does not support 3rd party devices.
Lastly, Logitech recommends displays go into “sleep” mode and not turn off. For those that need displays that turn off and to have the MTR turn them on, you can purchase Extron HD CTL-100 – this provides CEC on “injection” whenever HDMI sync is detected.
I hope this helps!
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Hi, this is a very interesting comment, thank you for these extremely useful information!
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All of the documentation by Logitech seems to assumes that you’re using a Windows PC. How do you go in and change the display settings if you’re using a chromebox instead?
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Hi Kevin, every Microsoft Teams Rooms use only (at this moment) a PC with Windows 10 Enterprise.
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If you refer to Logitech Tap bundle with other solutions like Zoom or Google, I’m sorry I cannot help you, I never seen that versions
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Hello together, what is the reason for my issue, if i use the table hub to connect the two HDMI Input with my PC i have only on one Display a Picture, the secound is black. What can be the Reason, is it the same that i have to connect the Display HUb with two HDMI to DVI cables ?
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Hi Thomas, try to lower (force) the screen resolution to Full HD into Windows.
Let me know. Best. Luca
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We use 2 screens with Logitech Rally. In meeting when a content is shared we receive the video stream on one screen and the content on the other.
Is it possible to have only the duplicated content on the 2 screens?
Thanks
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Hi, not easily, you have to set the MTR to single monitor and reboot it, and use an HDMI duplicator attached to the Display Hub and send the main video output to both monitors. Question: why do you use two display if you prefer to not split video and content?
Thanks. Best Regards. Luca
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Just use an EDID minder/emulator on your display inputs. Set the EDID minder to 1080p60Hz and all your woes will disappear. This also stops the annoying display flickering back and forth when then PC boots or wakes up from a sleep state. We use Lindy HDMI 10.2G EDID Emulator but there are plenty of options out there.
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Hi Jamus,
Agree, after this article I also used EDID emulator with great results. At the day of the article that was a “quick and dirty” workaround (but effective)
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this would help without EDI emulator….
https://learn.microsoft.com/en-us/microsoftteams/rooms/rooms-operations#scale-and-resolution
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Hi xmike13, I’m sorry but this will not solve the HUB issue.
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Hi all,
We have the Logitech Rally Plus connected to Logitech Roommate which is connected to x2 4k Mecer LED panels. When powered on, both displays do not show anything.
Would the HDMI emulators help with this problem? We are also experiencing it with the Rally Bar connected to x2 4K displays.
Logitech says the units can only support upto 1080p resolution.
Is there a work around? We would like to make use of both displays for live video and presentation.
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Hi Chuck, unfortunately you cannot use 2 4K monitors at full resolution, as Logitech said the max supported res is 2x FullHD. The EDID Emulator could help you in this case, presenting to the Logitech Display Hub a “FullHD monitor EDID code” instead of the real “4K EDID code”, allowing the system to work. Try it and let me know
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