1 Open Loop

Q: Display Port KVM Switch

Just wondering if anyone had some recommendations for a display port switch.

 

I'd like to switch a USB keyboard and a LED display (via Display Port) between two Mac computers. (Mac Pro and Mini)

 

Also, I was wondering how you handle a Bluetooth mouse in this situation.

Posted on Dec 29, 2011 6:26 AM

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Q: Display Port KVM Switch

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  • by mcabassol,

    mcabassol mcabassol Jan 19, 2012 11:31 AM in response to 1 Open Loop
    Level 1 (0 points)
    Jan 19, 2012 11:31 AM in response to 1 Open Loop

    1 Open Loop - I purchased one of these (av4pro-dp) to use with my setup. I have 4 Dell u2711's connected to my mac pro and wanted to attach my center monitor to the KVM. The goal would have been to have the primary monitor control the current computer while leaving the other monitors displaying my usual osx screens. In theory this sounds like a good idea... However, the av4pro-dp does not do monitor emulation. So essentailly it acts like you are unplugging the monitor from the computer and plugging it into the other. Needless to say, when you do this, all of the windows rearrange on the osx desktop. So this idea of EDIDs being emulated is NOT correct.

     

    Below is correspondence that I have with Adder support :

     

    Hi Michael,

     

    I received a response from our developers and they confirmed what I said yesterday over the phone that the video is disconnected from the computer at switch over and is connected to the next system. Please see the response I received below.

     

    When switching channels it simply disconnects the video from one computer and re-connects to next. It is not practical to ‘emulate’ a DisplayPort monitor on each computer port because of the complexity of the DisplayPort – Computer negotiation/link training scheme.

     

    The switches behaviour is the same as un-plugging and re-plugging a DisplayPort monitor from a computer – as part of the negotiation/link training process some computers operating systems decide to re-arrange the desktop icons and  windows – this is NOT a function of the DisplayPort switch, it is down to the computer and operating system, not all  computers do this, but a lot of them appear to do so.

     

    In light of this information I don't believe your planned configuration will work using these switches.

     

    Best Regards,

    Attila Pinter

     

     

    From that comment, it sounds like "we were trying to get the product out of the door and decided it wasn't worth our time to enable monitor emulation".

     

    I am very dissapointed in Adder and have promptly returned it. Not worth $600 bucks.

     

    Just thought you should know the experience.

  • by Kujako,

    Kujako Kujako Jan 19, 2012 11:37 AM in response to mcabassol
    Level 2 (270 points)
    Jan 19, 2012 11:37 AM in response to mcabassol

    Sorry to hear that. However you could still get some EDID emulators from Geffen or another company and use them with the KVM you purchased.

     

    They are not cheap however, but if you hunt around eBay you can find some deals.

     

    (example) http://www.ebay.com/itm/Gefen-DVI-Detective-EXT-DVI-EDID-/150737028623

  • by mcabassol,

    mcabassol mcabassol Jan 19, 2012 12:07 PM in response to Kujako
    Level 1 (0 points)
    Jan 19, 2012 12:07 PM in response to Kujako

    Yeah I thought about that, but I have yet to find a EDID emulator for displayport. The whole point of buying this particular KVM was that it's displayport and it's coming natively from the video card and then into the display. No adapters necessary... just straight, high speed digital link.

     

    If you want to run the resolutions that I am at, 2560x1440, then you need duallink dvi or displayport and not just dvi... that being said, the video card does minidisplay port... So the optimal way is to use displayport all around.

  • by 1 Open Loop,

    1 Open Loop 1 Open Loop Jan 20, 2012 4:35 AM in response to mcabassol
    Level 2 (362 points)
    Mac OS X
    Jan 20, 2012 4:35 AM in response to mcabassol

    I got a very similar reply from the same person at Adder at few days ago, as I had contacted them about this topic. I hadn't purchased the switch yet, but I was going to. Sorry to find out that it didn't work out. This unplugging behavior is what I'm trying to avoid.

  • by Kujako,

    Kujako Kujako Jan 20, 2012 9:31 AM in response to 1 Open Loop
    Level 2 (270 points)
    Jan 20, 2012 9:31 AM in response to 1 Open Loop

    The "unplugging behavior" is the reason for the EDID emulators, but I doubt we'll see mini-displayport versions any time soon as the displayport standard includes support for audio and other stuff. If you're not using the extended feature set of the displayport connector, it seems to make more sense to adapt it to DVI and go from there.

  • by Michael Bennett2,

    Michael Bennett2 Michael Bennett2 Mar 11, 2013 5:02 PM in response to mcabassol
    Level 1 (0 points)
    Mar 11, 2013 5:02 PM in response to mcabassol

    So, are there no DisplayPort KVMs that maintain connection?  EDID passthrough does not seem to be the "magic words" to enable this either.

     

    I tried the Gefen EXT-DPKVM-441 and while I had to return it because it was broken, it also appeared to disconnect the display from my MacBook Pro when switching.  It also said it did EDID passthrough in the manual.

  • by JeanNicolas,

    JeanNicolas JeanNicolas Jun 5, 2013 1:01 AM in response to X423424X
    Level 1 (0 points)
    Jun 5, 2013 1:01 AM in response to X423424X

    BT Mouse can be turned on and off through settings. Just make sure to turn it off on the first computer BEFORE turn it on on the second one.

  • by Fravadona,

    Fravadona Fravadona Aug 27, 2013 10:34 AM in response to 1 Open Loop
    Level 1 (0 points)
    Aug 27, 2013 10:34 AM in response to 1 Open Loop

    I purchased an ATEN's CS1944 which supposely have EDID/DisplayPort emulation through their VideoDynasync technology : Actually it doesn't work !!

     

    I'm currently discussing about it with ATEN's support. They updated my firmware once and now the KVM works better (my MacBookPro doesn't go to sleep when I switch to other workstations) but the EDID of the monitor is clearly not accessible by the connected workstations while they don't have the focus of the KVM, making the MacBookPro adjust the resolution (and blink a lot) each time it gets the focus ....

     

    ----- Still hoping that they will debug their firmware -----

  • by Michael Bennett2,

    Michael Bennett2 Michael Bennett2 Aug 27, 2013 10:52 AM in response to Fravadona
    Level 1 (0 points)
    Aug 27, 2013 10:52 AM in response to Fravadona

    According to a Gefen representative in their forums, what the KVM has to do is not only emulate the EDID, but also store it, because it doesn't get transmitted while the display sleeps, so it has to re-read it.

     

    Gefen says they are working on a device that will incorporate such a feature, but doesn't say when that device will be available.  As of 5 months ago, they said they didn't know of any KVM vendor that did this. :-/

  • by Fravadona,

    Fravadona Fravadona Aug 27, 2013 11:13 AM in response to Michael Bennett2
    Level 1 (0 points)
    Aug 27, 2013 11:13 AM in response to Michael Bennett2

    Here's the presentation of the ATEN's way to do "emulation" :

     

    <<...

    ATEN solves the switched EDID dilemma by adding specially configured EDID memory to its Video DynaSync™-equipped KVM switches. When such a KVM switch is connected to an EDID-enabled monitor and turned on, the switch reads the monitor’s EDID and stores it in non-volatile memory. This memory is made available at once to all the computers connected to the Video DynaSync™ equipped KVM, and these computers are able to use DDC sensing to instantly read out the KVM switch’s stored monitor EDID. HDCP connectivity is thereby maintained as well, preventing unwanted blockage of protected digital content.

    ...>>

     

    But Gefen is right : it doesn't work as expected at this time :-P

  • by Michael Bennett2,

    Michael Bennett2 Michael Bennett2 Aug 27, 2013 11:46 AM in response to Fravadona
    Level 1 (0 points)
    Aug 27, 2013 11:46 AM in response to Fravadona

    Until somebody fixes this, I'm slumming it with a USB switch (JU-SW0012-S1) and using dual-link DVI on the Mac Pro and MiniDP on the MacBook Pro and just switching inputs on the display.  Not paying hundreds of dollars for a solution not much better than that.

  • by Fravadona,

    Fravadona Fravadona Sep 4, 2013 4:41 AM in response to 1 Open Loop
    Level 1 (0 points)
    Sep 4, 2013 4:41 AM in response to 1 Open Loop

    There's an EDID emulator for DP coming which may be usefull for Macs and DP KVM switches

     

    http://www.gefen.com/kvm/ext-dp-edidp.jsp?prod_id=10909

  • by tbone74oz,

    tbone74oz tbone74oz Jan 2, 2014 7:09 AM in response to 1 Open Loop
    Level 1 (0 points)
    Jan 2, 2014 7:09 AM in response to 1 Open Loop

    Dragging up an old post here, but I'm interested to know if anybody found a solution?  I'm looking at purchasing something like this but they're not cheap so if it's not working properly I'm not interested.

     

    For anybody using the ATEN CS1944, I found that from the manual that the Video DynaSync which is supposed to address this isn't enabled by default.

     

    http://ep.yimg.com/ty/cdn/kvm-switch/cs1942-1944-s-2012-04-13.pdf

     

    Page 20 provides instructions to enable it.  Anybody here tried this?

  • by The hatter,

    The hatter The hatter Jan 2, 2014 7:33 AM in response to tbone74oz
    Level 9 (60,935 points)
    Jan 2, 2014 7:33 AM in response to tbone74oz

    Might want to look at this for basic KVM I use now with  Mac and PC that uses only MiniDisplay Port for two computers. $42

     

    Kanex SnapX - 2x Switcher for Mac

    http://www.amazon.com/gp/product/B0061TVB3O/r

     

    Not sure it helps but I like that there is no need for its own power, the MDP cables are built in. The downside: windows are reduced when I switch and the other system was in sleep mode.

  • by Warwick Teale,

    Warwick Teale Warwick Teale Apr 30, 2014 6:43 AM in response to Fravadona
    Level 3 (588 points)
    Apr 30, 2014 6:43 AM in response to Fravadona

    Hi Fravadona, I'm also looking at the Aten CS1944 4xport USB2.0 Mini diskplay Port Dual View KVMP Switch to utilise:

    •  Mac Pro 2013 -
    •  MacbookPro 2013 (#1)
    •  Mac Mini (2012 current)
    • a Dell PC used for 3DSMax / Rhino with Dual DVI o/put on the graphics card

    that are all to be managed from an Apple  27inches Thunderbolt display with USB 2.0 attached  Wacom Intuous 5 tablet and Apple Extended Keyboard.

     

    Note, We will be connecting the Dell's graphics card output to the Atem CS1944 using the  Apple DVI-Dual Link (and USB)  to mini display port adapter and cable

     

    We have local sourced (Sham Shui Po) male-to-male and male-to-female extender mini displayport cables of varying lengths to assist with connectivity with the macs and the CS1944.

     

    So far this solution looks good for these MACs and mini displayports and the local cost at $HK4350 (€435 / $USD561) is quite reasonable.

     

    I saw your post about concerns and am curious...

    1. Have you had any satisfaction with subsequent CS1944 firmware updates from Aten? I didn't see a specific download update for the Aten CS1944 in the firmware downloads at http://www.aten.com/download/download.php
    2. We are a Mac facility and sadly it seems the any Aten firmware update requires a windows os to do (.exe) . I'm hoping Crossover.app on OSX will do as a full windows os system is not something that we we use despite the apps on the Dell PC.
    3. on the control console you use (screen and kbd), have you been able to see the EDID info presented in the OSX system preferences/displays that is currently switched?

     

    Hear from you soon

    Many Thanks!


    Warwick

    Hong Kong

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