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Black Box Explains...Low-profile PCI serial adapters.

Ever notice that newer computers are getting smaller and slimmer? That means regular PCI boards won’t fit into these computers’ low-profile PCI slots. But because miniaturization is the rage in... more/see it nowall matters of technology, it was only a short matter of time before low-profile PCI serial adapters became available—and Black Box has them.

Low-profile cards meet the PCI Special Interest Group (PCI-SIG) Low-Profile PCI specifications, the form-factor definitions for input/output expansion. Low-Profile PCI has two card lengths defined for 32-bit bus cards: MD1 and MD2. MD1 is the smaller of the two, with cards no larger than 4.721 inches long and 2.536 inches high. MD2 cards are a maximum of 6.6 inches long and 2.536 inches high.

BLACK BOX® Low-Profile Serial PCI cards comply with the MD1 low-profile specification and are compatible with the universal bus. Universal bus is a PCI card that can operate in either a 5-V or 3.3-V signaling level system. collapse


Black Box Explains...10-Gigabit Ethernet.

10-Gigabit Ethernet (10-GbE), ratified in June 2002, is a logical extension of previous Ethernet versions. 10-GbE was designed to make the transition from LANs to Wide Area Networks (WANs) and... more/see it nowMetropolitan Area Networks (MANs). It offers a cost-effective migration for high-performance and long-haul transmissions at up to 40 kilometers. Its most common application now is as a backbone for high-speed LANs, server farms, and campuses.

10-GbE supports existing Ethernet technologies. It uses the same layers (MAC, PHY, and PMD), and the same frame sizes and formats. But the IEEE 802.3ae spec defines two sets of physical interfaces: LAN (LAN PHY) and WAN (WAN PHY). The most notable difference between 10-GbE and previous Ethernets is that 10-GbE operates in full-duplex only and specifies fiber optic media.

At a glance—Gigabit vs. 10-Gigabit Ethernet

Gigabit
• CSMA/CD + full-duplex
• Leveraged Fibre Channel PMDs
• Reused 8B/10B coding
• Optical/copper media
• Support LAN to 5 km
• Carrier extension

10-Gigabit Ethernet
• Full-duplex only
• New optical PMDs
• New coding scheme 64B/66B
• Optical (developing copper)
• Support LAN to 40 km
• Throttle MAC speed for WAN
• Use SONET/SDH as Layer 1 transport

The alphabetical coding for 10-GbE is as follows:
S = 850 nm
L = 1310 nm
E = 1550 nm
X = 8B/10B signal encoding
R = 66B encoding
W = WIS interface (for use with SONET).

10-GbE
10GBASE-SR — Distance: 300 m; Wavelength: 850 nm; Cable: Multimode
10GBASE-SW — Distance: 300 m; Wavelength: 850 nm; Cable: Multimode
10GBASE-LR — Distance: 10 km; Wavelength: 1310 nm; Cable: Single-Mode
10GBASE-LW — Distance: 10 km; Wavelength: 1310 nm; Cable: Single-Mode
10GBASE-LX4 — Distance: Multimode 300 m, Single-Mode 10 km; Wavelength: Multimode 1310 nm, Single-Mode WWDM; Cable: Multimode or Single-Mode
10GBASE-ER — Distance: 40 km; Wavelength: 1550 nm; Cable: Single-Mode
10GBASE-EW — Distance: 40 km; Wavelength: 550 nm; Cable: Single-Mode
10GBASE-CX4* — Distance: 15 m; Wavelength: Cable: 4 x Twinax
10GBASE-T* — Distance: 25–100 m; Wavelength: Cable: Twisted Pair
* Proposed for copper. collapse


Black Box Explains...Power problems.

Sags
The Threat — A sag is a decline in the voltage level. Also known as “brownouts,” sags are the most common power problem.

The Cause — Sags can be caused... more/see it nowlocally by the start-up demands of electrical devices such as motors, compressors, and elevators. Sags may also happen during periods of high electrical use, such as during a heat wave.

The Effect — Sags are often the cause of “unexplained” computer glitches such as system crashes, frozen keyboards, and data loss. Sags can also reduce the efficiency and lifespan of electrical motors.

Blackouts
The Threat — A blackout is a total loss of power.

The Cause — Blackouts are caused by excessive demand on the power grid, an act of nature such as lightning or an earthquake, or a human accident such as a car hitting a power pole or a backhoe digging in the wrong place.

The Effect — Of course a blackout brings everything to a complete stop. You also lose any unsaved data stored in RAM and may even lose the total contents of your hard drive.

Spikes
The Threat — A spike, also called an impulse, is an instantaneous, dramatic increase in voltage.

The Cause — A spike is usually caused by a nearby lightning strike but may also occur when power is restored after a blackout.

The Effect — A spike can damage or completely destroy electrical components and also cause data loss.

Surges
The Threat — A surge is an increase in voltage lasting at least 1/120 of a second.

The Cause — When high-powered equipment such as an air conditioner is powered off, the excess voltage is dissipated though the power line causing a surge.

The Effect — Surges stress delicate electronic components causing them to wear out before their time.

Noise
The Threat — Electrical noise, more technically called electromagnetic interference (EMI) and radio frequency interference (RFI), interrupts the smooth sine wave expected from electrical power.

The Cause — Noise has many causes including nearby lightning, load switching, industrial equipment, and radio transmitters. It may be intermittent or chronic.

The Effect — Noise introduces errors into programs and data files. collapse


Black Box Explains... Basic Printer Switches

Mechanical—A mechanical switch is operated by a knob or by push buttons and uses a set of copper or gold-plated copper contacts to make a connection. The internal resistance created... more/see it nowby this type of connection will affect your signal’s transmission distance and must be taken into account when calculating cable lengths.

Electronic—Although electronic switches are controlled by knobs and pushbuttons like mechanical switches, the switching is accomplished with electronic gates not mechanical contacts. Electronic switches don’t have the internal resistance of a mechanical switch—some even have the ability to drive signals for longer distances. And since they don’t generate electronic spikes like mechanical switches, they’re safe for sensitive components such as HP® laser printers. Some electronic switches can be operated remotely. collapse


Black Box Explains... Printer Sharing with Windows

Unlike the earlier DOS operating systems, Windows® doesn’t check to see if the printer is busy at the very beginning of the printing process. Windows will send out data to... more/see it nowstart a job even if the printer is signaling busy or unavailable. If your print sharer doesn’t have a buffer, critical printer-initialization information can be lost before your job is started. Once the initialization information is lost, the printer cannot interpret the job correctly.

A buffered print-sharing device is the most practical solution. When Windows starts printing to a buffered port, it “thinks“ it’s talking directly to the printer, and the critical initialization information is stored by the buffer. The buffer can send out a busy signal to Windows, so it delays sending more information until the buffer is accessible again. collapse


Black Box Explains...DIN rail usage.

DIN rail is an industry-standard metal rail, usually installed inside an electrical enclosure, which serves as a mount for small electrical devices specially designed for use with DIN rails. These... more/see it nowdevices snap right onto the rails, sometimes requiring a set screw, and are then wired together.

Many different devices are available for mounting on DIN rails: terminal blocks, interface converters, media converter switches, repeaters, surge protectors, PLCs, fuses, or power supplies, just to name a few.

DIN rails are a space-saving way to accommodate components. And because DIN rail devices are so easy to install, replace, maintain, and inspect, this is an exceptionally convenient system that has become very popular in recent years.

A standard DIN rail is 35 mm wide with raised-lip edges, its dimensions outlined by the Deutsche Institut für Normung, a German standardization body. Rails are generally available in aluminum or steel and may be cut for installation. Depending on the requirements of the mounted components, the rail may need to be grounded. collapse


Black Box Explains...Advantages of fiber optic line drivers.

Fiber optic line drivers are much better for communications than copper-wire alternatives because they offer three main advantages: superior conductivity, freedom from interference, and security.

Superior conductivity for increased performance
The glass... more/see it nowcore of a fiber optic cable is an excellent signal conductor. With proper splices and terminations, fiber cable yields very low signal loss and can easily support data rates of 100 Mbps or more.

Immunity to electrical interference
Because fiber optic line drivers use a nonmetallic conductor, they don’t pick up or emit electromagnetic or radio-frequency interference (EMI/RFI). Crosstalk (interference from an adjacent communication channel) is also eliminated, which increases transmission quality.

Signals transmitted via fiber optic line drivers aren’t susceptible to any form of external frequency-related interference. That makes fiber connections completely immune to damaging power surges, signal distortions from nearby lightning strikes, and high-voltage interference. Because fiber cable doesn’t conduct electricity, it can’t create electrical problems in your equipment.

Signal security
Electronic eavesdropping requires the ability to intercept and monitor the electromagnetic frequencies of signals traveling over a copper data wire. Fiber optic line drivers use a light-based transmission medium, so they’re completely immune to electronic bugging. collapse


Black Box Explains...Advanced printer switches.

Matrix—A matrix switch is a switch with a keypad for selecting one of many input ports to connect to any one of many output ports.

Port-Contention—A port-contention switch is an... more/see it nowautomatic electronic switch that can be serial or parallel. It has multiple input ports but only one output port. The switch monitors all ports simultaneously. When a port receives data, it prints and all the other ports have to wait.

Scanning—A scanning switch is like a port-contention switch, but it scans ports one at a time to find one that’s sending data.

Code-Operated—Code-operated switches receive a code (data string) from a PC or terminal to select a port.

Matrix Code-Operated—This matrix version of the code-operated switch can be an any-port to any-port switch. This means than any port on the switch can attach to any other port or any two or more ports can make a simultaneous link and transfer data. collapse


Black Box Explains... Manual switch chassis styles.

There are five manual switch chassis styles: three for standalone switches (Styles A, B, and C) and two for rackmount switches (Styles D and E). Below are the specifications for... more/see it noweach style.

Standalone Switches

Chassis Style A
Size — 2.5"H x 6"W x 6.3"D (6.4 x 15.2 x 16 cm
Weight — 1.5 lb. (0.7 kg)
Chassis Style B
Size — 3.5"H x 6"W x 6.3"D (8.9 x 15.2 x 16 cm)
Weight — 1.5 lb. (0.7 kg)
Chassis Style C
Size — 3.5"H x 17"W x 5.9"D (8.9 x 43.2 x 15 cm)
Weight — 8.4 lb. (3.8 kg)

Rackmount Switches

Chassis Style D (Mini Chassis)
Size — 3.5"H x 19"W x 5.9"D (8.9 x 48.3 x 15 cm)
Chassis Style E (Standard Chassis)
Size — 7"H x 19"W x 5.9"D (17.8 x 48.3 x 15 cm) collapse


Black Box Explains...How fiber is insulated for use in harsh environments.

Fiber optic cable not only gives you immunity to interference and greater signal security, but it’s also constructed to insulate the fiber’s core from the stress associated with use in... more/see it nowharsh environments.

The core is a very delicate channel that’s used to transport data signals from an optical transmitter to an optical receiver. To help reinforce the core, absorb shock, and provide extra protection against cable bends, fiber cable contains a coating of acrylate plastic.

In an environment free from the stress of external forces such as temperature, bends, and splices, fiber optic cable can transmit light pulses with minimal attenuation. And although there will always be some attenuation from external forces and other conditions, there are two methods of cable construction to help isolate the core: loose-tube and tight-buffer construction.

In a loose-tube construction, the fiber core literally floats within a plastic gel-filled sleeve. Surrounded by this protective layer, the core is insulated from temperature extremes, as well as from damaging external forces such as cutting and crushing.

In a tight-core construction, the plastic extrusion method is used to apply a protective coating directly over the fiber coating. This helps the cable withstand even greater crushing forces. But while the tight-buffer design offers greater protection from core breakage, it’s more susceptible to stress from temperature variations. Conversely, while it’s more flexible than loose-tube cable, the tight-buffer design offers less protection from sharp bends or twists. collapse

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