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The times they are a-changing: More and more users these days have gravitated toward LCD monitors featuring EDID, including those with legacy VGA video connectors, DVI and HDMI connectors, and now also DisplayPort connectors. To meet these new customer needs, ATEN provides KVM switches that incorporate Video DynaSync™ technology that are suitable for the individual desktop with a couple of computers, programmer/software testing environments with 2 to 4 computers, and larger server farms with many computers.

ATEN Video DynaSync™ is a patented technology that optimizes the KVM viewing experience. By storing the console monitor’s EDID, boot-up display problems are eliminated and operation is smoother, thanks to the switch’s ability to automatically show the correct display resolution when switching between ports. Video DynaSync™ ensures that the ideal video settings are maintained under all operating systems. In this article we’ll explain just how that works.

1. How does EDID work and what are some potential problems?

EDID is defined by the international video standards group VESA (Video Electronics Standards Association). EDID is data that is kept in a ROM/EEROM chip in the video display which stores pertinent data about that monitor’s capabilities in such a way that it can be"read" by a connected computer’s graphics card via a DDC conductor in the video cable. This scheme works quite well with a single video display and a single computer.

VGA, DVI, and HDMI have all been widely adopted, and DisplayPort is rapidly gaining ground. All these interfaces take advantage of an EDID/DDC channel. But when a regular KVM switch (without ATEN Video DynaSync™) is inserted between the computers and the monitor, there can potentially be problems with less-than-optimized video when switching between sources.

The DDC (Display Data Channel) is a digital connection between a monitor and a graphics card. DDC allows the display to communicate its EDID specifications to the graphics card. When you connect a computer whose graphics card supports EDID to an EDID-equipped monitor, the computer looks at the monitor’s EDID memory (via the DDC channel of the video cable) and it automatically sets its video output (according to EDID data) to the optimum resolution for that monitor. This resolution handshake is invisible to the end user, and it’s very helpful with direct-connector monitors, but it doesn’t automatically benefit a regular KVM switch solution. That’s because these KVM switches typically have no mechanism whereby the monitor’s actual EDID information can reach the unselected computers as they boot up, so their graphics cards could potentially generate incorrect output resolutions.

With simple KVM switching, a single monitor is able to connect to two or more computers as commanded by the user. When the various computers wired to the KVM switch are booted up, they may or may not be able to detect the monitor’s EDID; it depends on whether the switch has connected a given computer to the user’s monitor, and whether the DDC conveys the monitor EDID to the computer.

Some KVM switches offer a default EDID to the computers, but this default is just an arbitrary monitor resolution. While an arbitrary EDID may allow switched computers to boot up as though they had read the actual monitor EDID, the chances are that they’ll boot with a less-than-optimum resolution. In some cases the monitor may be unable to display anything when the user actually switches to them using an incorrect default EDID value, or the computer may take a while to re-sync to the correct monitor resolution. In rare cases (with too high a default EDID resolution) monitor damage can occur. None of these situations are desirable.

2. How ATEN Video DynaSync™ solves the switched EDID dilemma

The patented ATEN technology Video DynaSync™ relies upon EDID to facilitate a video resolution handshake between the monitor and the computer video output, even when the monitor and computer are isolated from one another by a KVM switch or extender.

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 the EDID 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 the KVM switch’s stored monitor EDID. HDCP connectivity is thereby maintained as well, preventing unwanted blockage of protected digital content.

In the event the monitor is not turned on or connected at the time the Video DynaSync™ KVM switch is turned on, the switch directly connects the selected computer to the monitor’s EDID so it is still able to get the needed EDID data. ATEN Video DynaSync™ also enables the KVM to store the EDID that it detected the last time it was used so that, when powered up the next time, the chances are the KVM switch will already have the correct monitor EDID – even if the monitor isn’t yet powered up. Since a suitable EDID is always present for the computers, there is no “seeking” time lost when switching among multiple computers, no blank screen, and no need to reboot computers just to get them to detect the optimum video resolution. It’s as though the computers each had a direct, full-time DDC connection to the user’s monitor EDID information.

3. ATEN Video DynaSync™ in an extended desktop

As outlined above, ATEN Video DynaSync™ provides various benefits to improve the user viewing experience in different scenarios that require switching between multiple computers from one console. The benefits do not end there, though. Across all industries there is an ever-increasing demand for multiple-monitor setups. Multi-display systems are widely recognized as a major factor in increasing productivity across wide range of desktop applications, including financial services, CAD/CAM design, and control rooms. In these extended desktop scenarios, Video DynaSync™ ensures that windows opened on an extended desktop will not revert to their default configurations on the main display when switching between ports, providing a smooth and uninterrupted user experience.

4. What can ATEN Video DynaSync™ do for you?

So how does ATEN Video DynaSync™ really benefit users? Without a switch that correctly handles EDID signals (via DDC and suitable memory registers) end users might continue to experience incorrect output resolution, fuzzy displays when computers don’t set themselves properly, or the user will have to reboot or manually reset each computer once it’s brought up on the switch. Sometimes computers will lose their EDID when the switch moves on to another channel, necessitating yet another round of manual resolution resetting or rebooting. To avoid such potentially frustrating and time-wasting events, including reboots due to lost HDCP “handshakes”, select a model of KVM switch that fully and correctly supports EDID monitors and graphics cards.

To discover the full range of ATEN KVM Switches that support Video DynaSync™ and find the solution for you, follow this link.