The High-Definition Multimedia Interface ^® (HDMI) is the first digital interface to combine uncompressed high-definition video, up to eight channels of uncompressed digital audio, and intelligent format and command... more/see it nowdata in a single cable. It is now the defacto standard for consumer electronics and high-definition video and is gaining ground in the PC world.

HDMI supports standard, enhanced, and high-definition video. It can carry video signals at resolutions up to and beyond 1080p at 60 Hz (and higher).

HDMI offers an easy, standardized way to set up home theaters and AV equipment over one cable. Use it to connect audio/video equipment, such as DVD players, a set-top box, and A/V receivers with an audio and/or video equipment, such as a digital TV, PCs, cameras, and camcorders. It also supports multiple audio formats from standard stereo to multichannel surround sound. Plus it provides two-way communications between the video source and the digital TV, enabling simple, remote, point-and-click configurations.

NOTE: HDMI also supports HDCP (High-bandwidth Digital Content Protection), which prevents the copying of digital audio and video content transmitted over HDMI cable. If you have a device between the source and the display that supports HDMI but not HDCP, your transmission won’t work, even over an HDMI cable.

HDMI offers significant benefits over older analog A/V connections. It’s backward compatible with DVI equipment, such as PCs, TVs, and other electronic devices using the DVI standard. A DVI-to-HDMI adapter can be used without a loss of video quality. Because DVI only supports video signals, not audio, the DVI device simply ignores the extra audio data.

HDMI standards
The HDMI standard was introduced in December 2002. Since then, there have been a number of versions with increasing bandwidth and/or transmission capabilities.

HDMI 1.0 has a maximum TMDS bandwidth of 4.9 Gbps. It supports up to 3.96 Gbps of video bandwidth (1080p/60 Hz or UXGA) and 8-channel LPCM/192-kHz/24-bit audio.

HDMI 1.1 (May 2004) added support for full-definition DVD audio.

HDMI 1.2 (August 2005) added support for one-bit audio for SACD (Super Audio CD).

HDMI 1.2a (December 2005) added Consumer Electronics Controls (CEC) capabilities, such as command sets for controlling multiple devices with a single remote.

HDMI 1.3 (June 2006), more than doubled the bandwidth from 4.95 Gbps to 10.2 Gbps (340 MHz). It offers support for 16-bit color, increased refresh rates, and added support for 1440p WQXGA. It also added support for xvYCC color space and Dolby True HD and DTS-HD Master Audio standards. Plus it added features to automatically correct audio video synchronization. Finally, it added a mini connector.

HDMI 1.3a (November 2006), HDMI 1.3b (March 2007), HDMI 1.3b1 (November 2007), and 1.3c (August 2008) added termination recommendations, control commands, and other specification for testing, etc.

HDMI 1.4 (May 2009) increased the maximum resolution to 4Kx 2K (3840 x 2160 p/24/25/30 Hz and 4096 x 2160/24 Hz). It added an HDMI Ethernet channel for a 100-Mbps connection between two HDMI devices. Other advancements include: an Audio Return Channel, stereoscopic 3D over HDMI (HDMI 1.3 devices will only support this for 1080i), an automotive connection system, and the micro HDMI connector.

HDMI 1.4a (March 2010) adds two additional 3D formats for broadcast content.

HDMI connectors
There are four HDMI connector types. Type A and Type B are defined in the HDMI 1.0 specification. Type C is defined in HDMI 1.3, and Type D is defined in HDMI 1.4.

Type A: 19 pins. It supports all SDTV, EDTV, and HDTV modes. It is electrically compatible with single-link DVI-D.

Type B: 29 pins. Offers double the video bandwidth of Type A. Use for very high-resolution displays such as WQUXGA. It’s electrically compatible with dual-link DVI-D.

Type C Mini: 19 pins. This mini connector is intended for portable devices. It is smaller than Type A but has the same pin configuration and can be connected to Type A cable via an adapter or adapter cable.

Type D Micro: 19 pins. This also has the 19-pin configuration of Type A but is about the size of a micro-USB connector.

HDMI cable
Recently, HDMI Licensing, LLC announced that cables would be tested as Standard or High-Speed cables.

Standard HDMI cable is designed for use with digital broadcast TV, cable TV, satellite TV, Blu-ray and upscale DVD players to reliably transmit up to 1080i or 720p video (or the equivalent of 75 MHz or up to 2.25 Gbps).

High-Speed HDMI reliably transmits video resolutions of 1080p and beyond, including advanced display technologies such as 4K, 3D, and Deep Color. High-Speed cables can also accommodate WQXGA cinema monitors (resolution of 2560 x 1600). High-Speed HDMI is the recommended cable for 1080p video. It will perform at speeds of 340 MHz or up to 10.2 Gbps, the highest bandwidth currently available over an HDMI cable.

Additional resources and licensing information is available at HDMI.org. collapse

A Gigabit Interface Converter (GBIC) is a transceiver that converts digital electrical currents to optical signals and back again. GBICs support speeds of 1 Gbps or more and are typically... more/see it nowused as an interface between a high-speed Ethernet or ATM switch and a fiber backbone. GBICs are hot-swappable, so switches don’t need to be powered down for their installation. collapse

The environment determines whether cable should be shielded or unshielded.

Shielding is the sheath surrounding and protecting the cable wires from electromagnetic leakage and interference. Sources of this electromagnetic activity... more/see it now(EMI)—commonly referred to as noise—include elevator motors, fluorescent lights, generators, air conditioners, and photocopiers. To protect data in areas with high EMI, choose a shielded cable.

Foil is the most basic cable shield, but a copper-braid shield provides more protection. Shielding also protects cables from rodent damage. Use a foil-shielded cable in busy office or retail environments. For industrial environments, you might want to choose a copper-braid shield.

For quiet office environments, choose unshielded cable. collapse

Before the introduction of the ServSwitch, accessing more than one CPU from a single keyboard, monitor, and mouse was problematic. Keyboard/video (KV) or keyboard/video/mouse (KVM) switches frequently caused CPUs to... more/see it nowlock up because the CPUs weren’t always receiving the signals they expected from the keyboard. Managing server farms was a nuisance because either each server needed its own keyboard, monitor, and mouse, it or was subject to frequent rebooting if used with a KVM switch.

The BLACK BOX® ServSwitch™ KVM Switch changed all that. The ServSwitch enables frequent switching between multiple CPUs (up to 3000!) without the danger of CPUs locking up. That’s because the ServSwitch is built with sophisticated circuitry that keeps feeding each CPU the keyboard and mouse signals it expects.

So why are we still selling preServSwitch keyboard/video switches? The Number 1 reason is many of our customers have preinstalled applications in which these switches are specified, so we keep stocking them as a service. Another reason is there is still some call for these switches for applications in which only limited switching is required.

However, for most KVM applications, we recommend a BLACK BOX® ServSwitch™ KVM Switch as the most reliable switching solution. We have ServSwitch products and accessories for everything from a simple desktop application to managing all the servers in your enterprise network.

Simplify and save with BLACK BOX® ServSwitch™ Technology! collapse

What is PoE?
The seemingly universal network connection, twisted-pair Ethernet cable, has another role to play, providing electrical power to low-wattage electrical devices. Power over Ethernet (PoE) was ratified by the... more/see it nowInstitute of Electrical and Electronic Engineers (IEEE) in June 2000 as the 802.3af-2003 standard. It defines the specifications for low-level power delivery—roughly 13 watts at 48 VDC—over twisted-pair Ethernet cable to PoE-enabled devices such as IP telephones, wireless access points, Web cameras, and audio speakers.

Recently, the basic 802.3af standard was joined by the IEEE 802.3at PoE standard (also called PoE+ or PoE plus), ratified on September 11, 2009, which supplies up to 25 watts to larger, more power-hungry devices. 802.3at is backwards compatible with 802.3af.

How does PoE work?
The way it works is simple. Ethernet cable that meets CAT5 (or better) standards consists of four twisted pairs of cable, and PoE sends power over these pairs to PoE-enabled devices. In one method, two wire pairs are used to transmit data, and the remaining two pairs are used for power. In the other method, power and data are sent over the same pair.

When the same pair is used for both power and data, the power and data transmissions don’t interfere with each other. Because electricity and data function at opposite ends of the frequency spectrum, they can travel over the same cable. Electricity has a low frequency of 60 Hz or less, and data transmissions have frequencies that can range from 10 million to 100 million Hz.

Basic structure.
There are two types of devices involved in PoE configurations: Power Sourcing Equipment (PSE) and Powered Devices (PD).

PSEs, which include end-span and mid-span devices, provide power to PDs over the Ethernet cable. An end-span device is often a PoE-enabled network switch that’s designed to supply power directly to the cable from each port. The setup would look something like this:

End-span device → Ethernet with power

A mid-span device is inserted between a non-PoE device and the network, and it supplies power from that juncture. Here is a rough schematic of that setup:

Non-PoE switch → Ethernet without PoE → Mid-span device → Ethernet with power

Power injectors, a third type of PSE, supply power to a specific point on the network while the other network segments remain without power.

PDs are pieces of equipment like surveillance cameras, sensors, wireless access points, and any other devices that operate on PoE.

PoE applications and benefits.
• Use one set of twisted-pair wires for both data and low-wattage appliances.
• In addition to the applications noted above, PoE also works well for video surveillance, building management, retail video kiosks, smart signs, vending machines, and retail point-of-information systems.
• Save money by eliminating the need to run electrical wiring.
• Easily move an appliance with minimal disruption.
• If your LAN is protected from power failure by a UPS, the PoE devices connected to your LAN are also protected from power failure.
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Click on the image below for a larger view.

When provisioning interactive touchscreens for busy, commercial display applications, it’s important to keep in mind the demands of such uses. For that reason, you have to choose an HID screen... more/see it nowdesigned specifically for harsh use in public spaces, whether in malls, retail stores, airports, or hospitals, and ensure that the screen fits the viewing environment.

Black Box’s NEC®/3M® Touchscreen LCDs are a good choice for such busy venues. Featuring chemically strengthened glass substrate and an advanced design, they are durable enough to withstand heavy daily use, making them ideal for busy interactive wayfinding, retail PoS/PoP, and visitor information service applications—including signage that you expect to operate 24/7 (and don’t want to have to service in the middle of the night).

For one, the touchscreen LCDs boast reliable touch performance, so customers aren’t forced to repeatedly press the glass to advance to the next screen or get their desired content to display. Fitted with 3M® MicroTouch™ Dispersive Signal Technology (DST) overlays, the LCD bezels are unlike most traditional touchscreens that detect touch by interrupting acoustic waves, optical fields, or infrared beams above the surface of the screen; the DST panels detect touch by interpreting bending waves within the glass substrate. High-speed processors and complex algorithms are used to interpret the information and precisely calculate the location of a finger contact, resulting in a fast and accurate touch response.

In addition, the NEC/3M LCD Touchscreen LCDs’ performance isn’t affected by dust and other on-screen contaminants, or even static objects or hands resting on the screens. They’re also designed to operate even if the surface itself is damaged.

Plus, the LCDs themselves are designed for extended use. Available in standard and industrial-strength versions, the professional-grade NEC LCDs boast high brightness and contrast ratios for rendering of crisp images and text in venues with lots of ambient light.

A sealed panel design prevents contaminants like dust, grease, or steam from damaging the LCD panel. Round-The-Clock Scheduler technology enables advanced scheduling of display powering up/down, which can increase the life of the panel while reducing power consumption.

The P Series NEC/3M LCD Touchscreen LCD versions offer additional protection. They boast an industrial-strength design with additional thermal protection and internal temperature sensors with fan-based technology. What’s more, a built-in ambient light sensor automatically adjusts the display’s brightness based on the application’s lighting conditions, helping to reduce energy consumption.
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A thermocouple is a device that measures temperature by using the fact that a junction between two different metals produces a varying voltage related to their temperature. Two common types... more/see it nowof thermocouple are Type J and Type K.

Type J thermocouples use iron paired with a nickel-copper alloy. Type J thermocouples may cover a temperature range of up to -40 to +1382° F (-40 to +750°C), and offer high sensitivity.

Type K, the most common type of thermocouple, uses nickel-chromium and nickel-aluminum alloys. Because Type K is an early specification, its characteristics vary widely; individual thermocouples may cover a range of up to -328 to +2462 °F (-200 to +1350 °C). collapse

Networking equipment—especially servers—generates a lot of heat in a relatively small area. Today’s servers are smaller and have faster CPUs than ever. Because most of the power used by these... more/see it nowdevices is dissipated into the air as heat, they can really strain the cooling capacity of your data center. The components housed in a medium-sized data center can easily generate enough heat to heat a house in the dead of winter!

So cool you must, because when network components become hot, they're prone to failure and a shortened lifespan.

Damage caused by heat is not always immediately evident as a catastrophic meltdown—signs of heat damage include node crashes and hardware failures that can happen over a period of weeks or even months, leading to chronic downtime.

Computer rooms generally have special equipment such as high-capacity air conditioning and raised-floor cooling systems to meet their high cooling requirements. However, it's also important to ensure that individual cabinets used for network equipment provide adequate ventilation. Even if your data center is cool, the inside of a cabinet may overheat if air distribution is inadequate. Just cranking up the air conditioning is not the solution.

The temperature inside a cabinet is affected by many variables, including door perforations, cabinet size, and the types of components housed within the cabinet.

The most direct way to cool network equipment is to ensure adequate airflow. The goal is to ensure that every server, every router, every switch has the necessary amount of air no matter how high or low it is in the cabinet.

It takes a certain volume of air to cool a device to within its ideal temperature range. Equipment manufacturers provide very little guidance about how to do this; however, there are some very basic methods you can use to maximize the ventilation within your cabinets.

Open it up.
Most major server manufacturers recommend that the front and back cabinet doors have at least 63% open area for airflow. You can achieve this by either removing cabinet doors altogether or by buying cabinets that have perforated doors.

Because most servers, as well as other network devices, are equipped with internal fans, open or perforated doors may be the only ventilation you need as long as your data center has enough air conditioning to dissipate the heat load.

You may also want to choose cabinets with side panels to keep the air within each cabinet from mixing with hot air from an adjacent cabinet.

Equipment placement.
Don't overload the cabinet by trying to fit in too many servers—75% to 80% of capacity is about right. Leave at least 1U of space between rows of servers for front-to-back ventilation. Maintain at least a 1.5" clearance between equipment and the front and back of the cabinet. And finally, ensure all unused rack space is closed off with blank panels to prevent recirculation of warm air.

Fans and fan placement.
You can increase ventilation even more by installing fans to actively circulate air through cabinets. The most common cabinet fans are top-mounted fan panels that pull air from the bottom of the cabinet or through the doors. For spot cooling, use a fan or fan panel that mounts inside the cabinet.

For very tightly-packed cabinets, choose an enclosure blower—a specialized high-speed fan that mounts in the bottom of the cabinet to pull a column of cool air from the floor across the front of your servers or other equipment. An enclosure blower requires a solid or partially vented front door with adequate space—usually at least 4 inches—between the front of your equipment and the cabinet door for air movement.

When using fans to cool a cabinet, keep in mind that cooling the outside of a component doesn't necessarily cool its inside. The idea is to be sure that the air circulates where your equipment's air intake is. Also, beware of installing fans within the cabinets that work against the small fans in your equipment and overwhelm them.

Temperature monitoring.
To ensure that your components are operating within their approved temperature range, it’s important to monitor conditions within your cabinets.

The most direct method to monitor cabinet temperature is to put a thermometer into your cabinet and check it regularly. This simple and inexpensive method can work well for for small installations, but it does have its drawbacks—a cabinet thermometer can’t tell you what the temperature inside individual components is, it can’t raise the alarm if the temperature goes out of range, and it must be checked manually.

Another simple and inexpensive addition to a cabinet is a thermostat that automatically turns on a fan when the cabinet's temperature exceeds a predetermined limit.

Many network devices come with SNMP or IP-addressable internal temperature sensors to tell you what the internal temperature of the component is. This is the preferred temperature monitoring method because these sensors are inside your components where the temperature really counts. Plus you can monitor them from your desktop—they’ll send you an alert if there’s a problem.

There are also cabinet temperature sensors that can alert you over your network. These sensors are often built into another device such as a PDA but only monitor cabinet temperature, not the temperature inside individual devices. However, these sensors can be a valuable addition to your cooling plan, especially for older devices that don't have internal sensors.

The future of cabinet cooling.
Very high-density data centers filled with blade servers present an extreme cooling challenge, causing some IT managers to resort to liquid-cooled cabinets. They’re still fairly new and tend to make IT managers nervous at the prospect of liquids near electronics, but their high efficiency makes it likely that these liquid-cooled systems will become more prevalent.

It’s easy, really.
Keeping your data and server cabinets cool doesn't have to be complicated. Just remember not to overcrowd the cabinets, be sure to provide adequate ventilation, and always monitor conditions within your cabinets. collapse

DisplayPort is a digital video interface that was designed by the Video Electronics Standards Association (VESA) in 2006 and has been produced since 2008. It competes directly with HDMI®. Unlike... more/see it nowHDMI, however, DisplayPort is an open standard with no royalties.

This digital interface is used primarily between a computer and a monitor or a high-definition television and is built into many computer chipsets produced today. It’s incredibly versatile, with the capability to deliver digital video, audio, bidirectional communications, and accessory power over a single connector.

DisplayPort v1.1 supports a maximum of 10.8 Gbps over a 2-meter cable; v1.2 supports up to 21.6 Gbps. DisplayPort v1.2 also enables you to daisychain up to four monitors with only a single output cable. It also offers the future promise of DisplayPort Hubs that would operate much like a USB hub.

The standard DisplayPort connector is very compact and features latches that don’t add to the connector’s size. Unlike HDMI, a DisplayPort connector is easily lockable with a pinch-down locking hood, so it can't be easily dislodged. However, a quick squeeze of the connector releases the latch.

DisplayPort supports cable lengths of up to 15 meters with maximum resolutions at cable lengths up to 3 meters. Bidirectional signaling enables DisplayPort to both send and receive data from an attached device.

With the proper adapters, DisplayPort cable can carry DVI and HDMI signals, although this doesn’t work the other way around—DVI and HDMI cable can’t carry DisplayPort. Because DisplayPort can provide power to attached devices, DisplayPort to HDMI or DVI adapters don’t need a separate power supply.

The Mini DisplayPort (MiniDP or mDP) is a miniatured version of the DisplayPort interface. It carries both digital and analog computer video and audio signals. Apple® introduced the Mini DisplayPort connector in 2008 and it is now on all new Mac® computers. It is also being used in newer PC notebooks. This small form factor connector fully supports the VESA DisplayPort protocol. It is particularly useful on systems where space is at a premium, such as laptops, or to support multiple connectors on reduced height add-in cards.

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