Universal Robots Forum

Cannot connect mDP to HDMI matrix

I have been trying to resolve this issue for quite a long time (more then a year), but have not found a solution yet.

I have 2 UR5s in a classroom and two 4K TVs with ATEN 4by4 HDMI matrix. The thought was to show the screen of the teach pendant on the TVs, so the students could see it from their desks. Unfortunately I cannot get the image source from the controller to any device with HDMI.

I have tried the following:

  • Direct miniDP to HDMI cable - Not working
  • Passive miniDP to HDMI convertor - Not Working
  • Active miniDP to HDMI convertor - Not Working (also the controller did not boot with error: “no option to boot to”)
  • Active miniDP to VGA convertor - Working
  • miniDP to DP cable - Working (naturally…)

I tested most of the above with the TV, the HDMI matrix and regular office monitor with 2560*1440 resolution.

I am considering last few steps to take before resigning on this issue completely:

  • Update Controller firmware and try again all of above
  • Get VGA to HDMI convertor and be happy with whatever result (cut-off, flickering, noised images)

Please, can you tell me, how is it possible, that no HDMI conversion is working? What could be the cause? What are the next steps to take? Thank you.

I have read this topic Connect external screen / monitor and even bought that active miniDP to HDMI convertor, but still without success.


Hi @xcizek ,

Sorry to hear you’re having trouble with this. I have an active MiniDP to HDMI convertor working fine here, so it certainly is possible.

I would look at your convertor for the possible cause as it should certainly not prevent the controller from being able to find it’s boot media.

Could you possibly try to buy a different brand of convertor? For your reference I am using an unbranded one that looks like this, bought it from a Chinese site so unfortunately no brand/model details to hand.

Have you powered up the monitor FIRST w/ ACTIVE mini display port then pressed the power button on the pendant? I read another post where someone accidentally sliced the cable to the pendant and they were having this issue as well but using a active converter and powering the monitor up first is the correct way.

Also I’ve heard this mini display port to hdmi works Amazon - Mini Active Display Port to HDMI

Do you have a Linux/Windows PC that could run a Virtual Machine or do you need to use the physical robot? You could run URsim which is basically the Polyscope environment on the pendant. With a keyboard + mouse it also makes it quicker to type script or other commands (only downside is you can’t manually teach points by dragging robot around) Setting up URsim

Anyways, this might be alittle beyond me but hope this helps and best of luck!

Hello Michael,
thank you for the response.

I have always powered the robot through the button on the pendant after setting everything on the monitor. Some of the adapotrs did not even woke the screen. Some did that but with no signal and the monitor went to sleep again. I also tried setting the monitor to active signal seeking, but the results were the same. The pendant cable is fine.

The robots have not seen much usage because the labs were closed due to covid, but they are not closed anymore and we are expecting a lot of lessons would use them. I have 16 Windows PCs in that classroom and all have the URsim ready, but the teachers reported some sketchiness to the virtual environment (bad rendering of surfaces from time to time and so on). I have tried reconfiguring the virtual machine with various settings, but did not find anything that would remove the glitches. The teachers decided to use 27" LCD with direct DP connection to show the screen from the robot to students instead of using URsim and displaying it on the TVs but it is only temporary solution.

I will definitely try that adaptor and post back the results, if it works.
Thanks again :slight_smile: !

Hello @ajp,
I tried the following convertors:

  1. PremiumCord + miniDP to DP adaptor
    With this one, I managed to get signal from the DP output and VGA output. I am considering converting the analog singnal back to digital with another convertor to HDMI (I know: scratching your right ear with left hand), but i have tu buy that kind of convertor first

  2. big white one :slight_smile:
    This one caused the bad boot of the controller (repeatedly), so I am not considering this one. I attached the only label I could find on the package.

  3. small black + miniDP to DP adaptor
    No brand on it and it did not do anything.

  4. small white
    Again no brand on it, but I suspect it came with some of our older iMacs. Did not do anything too.

Seems I cannot upload more then one image in a reply, so see images bellow.

I tried all of them in a PC with Quadro GPU and the same monitor I used with the robot and can confirm they are in working order.

I will try to use another adaptor posted by Michael.

One more thing I would like to ask is, if there is any documentation on the spcifications of the miniDP output from the controller?

Thank you very much.


Big White label

small black

small white

Don’t know if you’ve tried this yet or not, but I found that it matters WHEN you plug the monitor in. (I know that sounds stupid.) Make sure the controller is powered off, and the monitor is unplugged from the mD port (but keep the power cable plugged in). Then, turn on the controller. When you hear the fans spin up, THEN plug the monitor in. This is only for the first time, when Linux does whatever it does to install drivers. After this initial time, I’m able to plug/unplug the monitor whenever.

Aside from that, this is the converter I have used on multiple robots:

As @michael.r.mercer correctly states, it must be an ACTIVE converter.

Alternatively, you can look into installing a VNC on your robot. I found a link somewhere else on this forum that has a magic file that makes it super easy. You just insert a flashdrive and you’re done. Then you just download any VNC software on your computer (I use VNC Viewer for Windows) and you can remote into the robot via the computer. This lets you control the robot from your computer which might be an additional advantage, or not. But either way, you can then just share your COMPUTER screen to your TVs.

Hopefully just plugging in the monitor right when the fans turn on does the trick for you though.

Thank you @eric.feldmann,

I will try that in few days, we are currently migrating some Vmware stuff and HW. I have ordered another active convertor from local store 4K Mini DisplayPort to HDMI Active Adapter - VC981, ATEN Video Converters | ATEN Corporate Headquarters (will arrive tomorrow) while waiting on the one from amazon. Spare ones are always handy.

That VNC remote control sounds interesting, I might look into that and convince the teachers, that it might be good to have it. I have installed network just for this occasion a few years back. Now it might finally see some use.

Attaching more relevant links as well for your browsing or if need be:

Teach Pendant Cable Splicing where I found the hmdi converter, I have not had to use an adaptor thankfully for any of mine yet but it seems like quite the hassle so hopefully UR can make this easier in the future.

Remote Desktop to Controller UI - VNC I believe this is the VNC with magic files referenced above. This might also be an option.

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Hi @xcizek,

So none of those specifically say they are Active convertors right?

I think some graphics cards (i.e. the one in your PC have the smarts to detect that an HDMI format signal is required and do the conversion without an active convertor, but alas the e-Series controller does not.

All of the convertors that I am aware of working successfully, including the one posted by Michael above specify Displayport 1.2 compatibility, and I can see one of yours only lists 1.1. So that’s another spec to pay attention to I think. (Whether there are 1.1 convertors that are also active, I’m not sure).

From what you’ve listed above I would be fairly confident that you’ll have success if you get a convertor with the right spec. Try to get hold of the one Michael mentioned if you can.

Hello @ajp,
I guess that big black one from PremiumCord is an active one, because it requires 5V USB power, otherwise it does not do anything at all. It is not old also, we bought it few months back, but I found out that its spec is only DP 1.1. The others are older and probably have DP 1.1 spec also and I am not sure whether they are active or not. I guess you could be right and I need DP spec 1.2 with active convertor.

Hopefully I will find out tomorrow, when the one from Aten will arrive. If that one does not work, I will have to wait for the one from Amazon.

UR Linux has fairly limited amount of display configuration it can work with.
It’s possible to set custom configurations that match your display with xrandr command line tool. Unfortunately it’s fairly advanced topic.

Using VNC is more convenient option.

Hi everyone,

I can confirm that this one 4K Mini DisplayPort to HDMI Active Adapter - VC981, ATEN Video Converters | ATEN Corporate Headquarters works. PPL lost my package and it took a while for them to find it, hence the delay.

It really looks like the adaptor has to have a DP 1.2 spec to work with the controller.

I thank you for your information and ideas you’ve given me. I appreciate it.

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