Blog posts of '2012' 'February'

What is a KVM switch?

Computer Servers are available in compact 1U/2U rack-mount configurations, these days. So, one can place multiple servers in a single rack which can save a lot of space in a server room/ data center. 

Since computer servers are similar to normal computers and each of them run different applications, each server requires a keyboard, mouse and monitor/ video terminal. At the same time, people do not sit and work on the servers all the time, unlike how they do with computers. Most of the servers are on an auto-run mode but they do require display, data input/output occasionally. 

So, it is actually a good idea to share a single keyboard, mouse and monitor for multiple servers as,

1. They are used occasionally.
2.One set of keyboard, mouse and monitor for each server occupies a lot of space, which is a premium in data centers.
3.The cost of buying separate monitor for each server can be quite high.
That's exactly the reason why we have KVM Switches – To share a single set of keyboard, mouse and display terminal (monitor) across multiple servers. 

Every KVM Switch has connections to connect with the keyboard/ mouse ports of each server using USB interface or PS/2 interface or both. It also connects to the monitor port of each server using VGA interface. So, now we have many servers at one side whose keyboard, mouse and monitor ports are connected directly to the KVM Switch. 

On the other side, we have the control terminal that consists of a single set of keyboard, mouse and monitor that connects to the KVM Switch as well. They can connect using USB interface, PS/2 interface or both. Using this one set, it is possible to select which server we want to control/ access via the KVM Switch.

A user can select which server they want to work with, by using a toggle switch provided on the KVM Switch or by using keyboard short-cuts from the control terminal or by using a menu driven on-screen display from the control terminal. 

In most cases, the KVM switch itself is rack-mountable and a separate pull-out tray is available with some rack vendors that can accommodate the keyboard, mouse and an LCD monitor within the rack itself. 

When all the servers and the monitoring terminals are connected in this way, one can just start working because the entire set-up is plug and play. So, there is no need to install device drivers or any other software on the servers/ KVM switches.

There are multiple KVM switch models available based on the number of servers/ computers they can control/ communicate with. Commonly available models are 2-Port KVM Switch, 4-Port KVM Switch, 8-Port KVM Switch, 16-Port KVM Switch, etc.

KVM Switches generally support servers/ computers running on multiple operating systems like Windows, Linux, Mac OSX, etc. Some KVM Switches can even emulate keyboard/ mouse/ video terminals on all the connected servers, so that there would not be a 'no-input/output device attached' error, if and when they re-boot (during power-cuts, for example).

Many KVM Switches can be cascaded together (using special cables) in order to increase the number of servers that can be controlled using a single control terminal (keyboard, mouse, monitor). 

The KVM Switch network is a proprietary network and there is no interference with other LAN traffic,etc. Most of the KVM Switches support a bandwidth of 200 MHz or higher and a resolution of up to 1920 x 1440, which is sufficient to support HD Video output.   

KVM Switches come with all the cables needed to attach to the individual server keyboard, mouse and video (display terminal) interface ports.

Common KVM Switches are available in the following configurations.

•16 Port USB & PS/2 COMBO KVM switch
•8 Port USB & PS/2 COMBO KVM switch
•4 Port USB & PS/2 COMBO KVM switch
•2 Port USB & PS/2 COMBO KVM switch
•8 Port USB & PS/2 COMBO KVM switch with remote control 
•4 Port Auto USB KVM switch
•2 Port Auto USB KVM switch
•4 Port PS/2 KVM switch
•2 Port PS/2 KVM switch


HDMI AV switch

HDMI Switches – Multiple HDMI Sources to Multiple HDMI Output units

HDMI Interfaces have become very popular to connect High Definition Audio-Video Systems like DVD Players, Blue-ray disk players, Cable Set top boxes, Satellite receivers, HD Gaming units, etc. 

There are special HDMI Cables that connect these sources to HD display units like LCD Displays, Plasma Displays, LED TV's, LCD/ DLP Projectors, etc. 

HDMI Switches are used to connect both the HDMI Sources and HDMI display units together in a single box so that one can select which source they want to connect to which display unit, at any  point of time. 

There are two types of HDMI Switches – N x 1 & N x N. 


The N x 1 HDMI Switches allow a user to connect multiple HDMI Sources to one HD Display unit. User can select which source they want to connect to the display unit at a given point of time, either using the remote control that is supplied along with the HDMI Switch (mostly) or using the On-device switch knob. 

This is quite comfortable for the user because they don't have to disconnect a device from the display unit and re-connect the same, by physically plugging and UN-plugging cables every time they want to move between the Blue ray player and the Cable/Satellite receiver, for example. 

All the connections can be permanently made and the user can just use the remote control to select which HDMI Source they want to connect with their HDTV. They can even connect and select from up to five HDMI Sources using common HDMI Switch models that allow up to 5 x1 connectivity. The 3 x 1 HDMI Switch model is another popular model among HDMI N x 1 Switches.

The N x N HDMI Switches allow a user to connect multiple HDMI Sources to multiple HD Display units. This could be useful in situations where a user has multiple HD sources and multiple  HD displays and want to be able to select which source they want to connect to which display unit. 

For example, users might want to watch a movie using a HDMI supported LCD/ DLP projector in the weekend. But they don't always want to connect the Blue ray player to the projector as the bulb life in any projector is limited. By pressing a single button on the IR remote control of their HDMI Switch, they might be able to switch to their Plasma/ LED TV's on weekdays. 

In normal cases, users might have to physically plug the cable to the LCD/DLP Projector and Plasma/LED TV every time. But, with N x N HDMI Switches, they can permanently connect all their input sources and all their output sources to a single HDMI switch and use the remote to decide which source connects to which display. 

There is no need to wade around complex set of cables and in most cases, there is no need to even get up from their seat. One touch on the remote control decides where they see what. Its simple and effective! The common N x N HDMI Switch configurations include 5 (Input) x 4 (Output) & 3 (Input) x 2 (Output).

Some HDMI Switches can even extend the range of the HDMI connections (distance over which HDMI signals can be carried over HDMI cables) as they can equalize and re-lock the HDMI signals passing through them. Some of them even support HDMI and HDCP Pass through capabilities. 

The HDMI Switches generally maintain the resolution of the High Definition displays passing through them – So, they support the highest HD Standard - 1080p & a high computer display resolution of up to 1920 x 1200 pixels. So, there is no downgrading of the HD signals passing through the HDMI Switches.

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What is HDMI Splitter?

HDMI Splitter – Connect Multiple Displays using a Single HD Source





The HDMI Interface/ HDMI Cables have become very popular for connecting High Definition Sources with High Definition Displays. Since the HDMI Cables can carry audio along with HD video, its an additional advantage as it reduces the clutter (due to many cables) around a home-theater unit. 

So now, users can connect their HD DVD players to a Plasma/ LED Screen using a single HDMI Cable between them to enjoy high quality HD video. But we know that the DVD player is placed very close to the display unit and both of them are connected directly using a HDMI cable. 

The HD DVD Player/ HD Satellite Receiver are normally kept in the living room, along with Plasma TV/ LED TV or other display units. In any family, there are situations when multiple family members want to watch the same TV show/  Movie from different places. 

For example, the lady of the house might want to have a display in kitchen and watch the video programs while cooking. Working professionals might want to lie down on their bed in their bedroom and watch TV for some time, before sleeping after a tiring day. In many houses, there are multiple rooms and family members might want to view video programs right from their own room. 

One can buy multiple displays and place it where ever users want them. But what about Satellite receivers /Cable Set-top boxes? Users cannot buy multiple such units as each unit incurs additional monthly costs. And the same DVD cannot be played using multiple DVD players!

That's where the HDMI splitter comes in very handy. The function of a HDMI splitter is to replicate the same HD source (from DVD Player, Satellite receiver, etc) and display them simultaneously on more than a single HD display unit (LED Display, Plasma TV, etc). The best thing about a HDMI splitter is, they can replicate audio signals along with the video signals!

There are various models of the HDMI splitters which can split/ replicate a single video source into two, four or even eight independent video streams that can be displayed on two, four or eight independent monitors connected to the splitter. 

So, in every HDMI splitter, there is one HDMI In port where the source is connected using a HDMI Cable and there are multiple HDMI Out ports where the displays can be connected, also using HDMI Cables. There is no need to carry separate audio cables for each display as audio signals are split (replicated) along with the video signals.

Most of the HDMI splitters maintain the source resolution as such. If a 720p HD source is played from a DVD Player, all the screens display the same 720p HD video. Hence, there is no reduction of video resolution while using the HDMI splitter. Many splitters support up to 1080p HD resolutions, which is the highest commercially available HD resolution for now. 

It is also important to remember that the maximum distance over which HDMI signals can be carried by HDMI cables are limited. So, special quality HDMI cables or HDMI extenders can be used to extend their distances. 

In some cases, its even possible to use Remote Control extenders to control the HD DVD player/ Cable Set-top box kept at the living room, right from the kitchen or bedroom.

HDMI splitters are compatible with HDCP protocol which maybe required to combat piracy in HD video. So, a HDMI splitter is a small device but extends your home theater to multiple locations within your house. You can even have up to eight screens displaying the video/audio from the same source across the house! 

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What is VGA Switch?

While a VGA Splitter can connect a single source to multiple monitors, a VGA Splitter can connect multiple sources to a single monitor (or) multiple monitors and allows one to decide which input source needs to connect to which output source.

For example, if there are two computer CPU's and two monitors, the video outputs of both the CPU units could be connected to VGA-IN ports of the VGA Switch. Similarly, the two monitors connect to the VGA-OUT ports of the VGA Switch. Now the user can decide if,

  1. The output of the first CPU needs to be displayed in both the monitors (or)
  2. The output of the second CPU needs to be displayed in both the monitors (or)
  3. The output of the first CPU needs to be displayed in the first monitor and second CPU in the second monitor, etc.

The VGA Switch can also reinforce the images while displaying them in multiple monitors and can extend the range (distance) over which the VGA signals can be carried.

VGA Switches can be useful in situations where one works simultaneously on multiple computers and multiple monitors. The number of monitors required in such situations can be reduced with a VGA Switch. They can also be used to display the output of the same source to multiple monitors.

The common VGA Switch models are:

2 in 2 out VGA switch 250MHZ
4 in 4 out VGA switch 450MHZ


{vga splitter}

VGA Monitor Splitter

A VGA Cable is sufficient if one wants to connect a single source (CPU) to a single display. But, what if the same image/video output (from the PC) needs to be displayed on more than one monitor simultaneously?

A VGA Splitter can be used for that purpose. A VGA Splitter will split the input imagery in to two or more similar output imagery using integrated electronics.

For example, if one wants to see the same output image on two or more monitors or if one wants the image output to appear both on the projector screen and the computer monitor simultaneously, a VGA splitter could be used. VGA Splitters can be useful in schools where the teacher wants to show the same image output to multiple student monitors simultaneously.

There are Y-Cables that can split the VGA signal into two and display it on two monitors. But there is a considerable reduction in the quality of images when Y-cables are used to split them, as it is just a passive unit. They can only connect to a maximum of two monitors.

There are powered Active VGA Splitters that are hardware units. These units can reinforce the image signals so that there is no loss of quality in any of the display units connected to them. Further, they can even extend the length over which VGA signals can be carried. So, if one monitor is in the next room, Active VGA Splitters can still connect to them and display the imagery.

Active VGA Splitters can connect the same source to more than two display units, depending on the number of output ports present in the unit.

The commonly used splitter configurations are -

2 Port VGA splitter (250MHz)
4 Port VGA splitter (350MHz)
8 Port VGA splitter (450MHz)
16 Port VGA splitter (450MHz)


{vga video splitter}

Cable VGA to VGA

VGA stands for Video Graphics Array. VGA is the most popular video format used by Computers/ LCD Projectors, etc.  A Computer CPU has a VGA-Out port through which the imagery/ video is carried via a VGA Cable to be displayed on the Computer Monitor – CRT/ LCD Monitor, Plasma/LED Display terminal, LCD Projector, etc. VGA format can support multiple image resolutions. 

VGA Cables are required to connect VGA Ports in CPU to Computer monitors, plasma displays, LCD monitors, Projectors, etc. They are also used to connect the VGA Splitters and VGA Switches to display units.

The commonly available VGA Cable lengths are : 1.5 meters, 3 meters, 5 meters, 10 meters, 15 meters, 20 meters, 30 meters, etc. 


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VGA AV to HDMI Converter

Most of the latest display terminals in the market come with HDMI ports that support High Definition display format. Some of them can take an input signal from a PC/ Computer in certain HDMI ports.

But the issue is, computers do not come with HDMI ports! They come with VGA ports for video and audio-out ports for audio. So, if one wants to connect their computer output to a Plasma/ LED/ LCD/ DLP display terminal using a HDMI cable, they would need an VGA + Audio to HDMI Converter.

A VGA cable and audio cable connects from the PC/ Laptop to the Converter and a HDMI cable connects to the display terminal from the converter. HDMI Cable can carry both image and voice together. So, one cable is sufficient on the monitor side.


But please be aware that only certain resolutions of the computer display are supported by the converter. So, the computer/ laptop display needs to be adjusted accordingly (to one of the resolutions supported) while connecting with the VGA to HDMI converter.

The images are rendered as such by the converter, and there is no up-conversion or down-conversion of the resolutions/ change in format.

The VGA + Audio to HDMI converter could be useful if one wants to see videos on a bigger screen (or) if one wants to browse the net from a distance (using wireless keyboard/ mouse, for example).

{vga to hdmi}

VGA to AV S-Video Converter

VGA refers to Video Graphics Array and it is the most popular format for displaying output images on a PC (monitor), LCD projector, etc. Every PC (CPU) has a VGA-OUT port from which a VGA Cable carries the images to be displayed on the computer monitor (CRT/ LCD Monitor). VGA can generally support multiple resolutions, depending on the source and the display unit. 

A simple VGA cable is sufficient if one wants to connect the CPU of a PC to a Computer Monitor/ LCD display directly.

But there are certain situations when one wants to connect the video output of a computer to a CRT TV (normal TV), instead of the computer monitor. Youtube videos, games and streaming movies/ video shows (for example) look bigger and better on a TV monitor.

In such situations, the VGA to AV/S-Video Converter can be used. This converter box is a small hardware unit that has one VGA Input port (which connects to the CPU) and three Output ports – S-Video, AV and VGA pass through.

Any of these ports can be used to connect to various display units (including CRT TV, which mostly connects using an AV interface). The S-Video output can be used to connect to an LCD/Plasma display units.

The LCD/Plasma display terminals may have a VGA port as well, but if the computer is far away from it, buying a long VGA cable might be quite expensive. One might want to use a long AV/S-Video cable instead.

The VGA Out port is actually a Pass-through port because it can be used to connect to computer displays/ LCD projectors using VGA Cables, without disturbing the other connections.

Most of the VGA to AV/S-Video Converters are plug-and-play devices. So, there is no need to install separate device drivers, etc for them to work with computers.

One may not expect the same clarity for data display over CRT monitors (when compared to computer monitors), but for video and other larger images, the clarity should be good enough. 


{S-Video Converter}