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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...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...USB.

What is USB?
Universal Serial Bus (USB) is a royalty-free bus specification developed in the 1990s by leading manufacturers in the PC and telephony industries to support plug-and-play peripheral connections. USB... more/see it nowhas standardized how peripherals, such as keyboards, disk drivers, cameras, printers, and hubs) are connected to computers.

USB offers increased bandwidth, isochronous and asynchronous data transfer, and lower cost than older input/output ports. Designed to consolidate the cable clutter associated with multiple peripherals and ports, USB supports all types of computer- and telephone-related devices.

Universal Serial Bus (USB) USB detects and configures the new devices instantly.
Before USB, adding peripherals required skill. You had to open your computer to install a card, set DIP switches, and make IRQ settings. Now you can connect digital printers, recorders, backup drives, and other devices in seconds. USB detects and configures the new devices instantly.

Benefits of USB.
• USB is “universal.” Almost every device today has a USB port of some type.
• Convenient plug-and-play connections. No powering down. No rebooting.
• Power. USB supplies power so you don’t have to worry about adding power. The A socket supplies the power.
• Speed. USB is fast and getting faster. The original USB 1.0 had a data rate of 1.5 Mbps. USB 3.0 has a data rate of 4.8 Gbps.

USB Standards

USB 1.1
USB 1.1, introduced in 1995, is the original USB standard. It has two data rates: 12 Mbps (Full-Speed) for devices such as disk drives that need high-speed throughput and 1.5 Mbps (Low-Speed) for devices such as joysticks that need much lower bandwidth.

USB 2.0
In 2002, USB 2.0, (High-Speed) was introduced. This version is backward-compatible with USB 1.1. It increases the speed of the peripheral to PC connection from 12 Mbps to 480 Mbps, or 40 times faster than USB 1.1.

This increase in bandwidth enhances the use of external peripherals that require high throughput, such as printers, cameras, video equipment, and more. USB 2.0 supports demanding applications, such as Web publishing, in which multiple high-speed devices run simultaneously.

USB 3.0
USB 3.0 (SuperSpeed) (2008) provides vast improvements over USB 2.0. USB 3.0 has speeds up to 5 Gbps, nearly ten times that of USB 2.0. USB 3.0 adds a physical bus running in parallel with the existing 2.0 bus.

USB 3.0 is designed to be backward compatible with USB 2.0.

USB 3.0 Connector
USB 3.0 has a flat USB Type A plug, but inside there is an extra set of connectors and the edge of the plug is blue instead of white. The Type B plug looks different with an extra set of connectors. Type A plugs from USB 3.0 and 2.0 are designed to interoperate. USB 3.0 Type B plugs are larger than USB 2.0 plugs. USB 2.0 Type B plugs can be inserted into USB 3.0 receptacles, but the opposite is not possible.

USB 3.0 Cable
The USB 3.0 cable contains nine wires—four wire pairs plus a ground. It has two more data pairs than USB 2.0, which has one pair for data and one pair for power. The extra pairs enable USB 3.0 to support bidirectional asynchronous, full-duplex data transfer instead of USB 2.0’s half-duplex polling method.

USB 3.0 Power
USB 3.0 provides 50% more power than USB 2.0 (150 mA vs 100 mA) to unconfigured devices and up to 80% more power (900 mA vs 500 mA) to configured devices. It also conserves power too compared to USB 2.0, which uses power when the cable isn’t being used.

USB 3.1
Released in 2013, is called SuperSpeed USB 10 Gbps. There are three main differentiators to USB 3.1. It doubles the data rate from 5 Gbps to 10 Gbps. It will use the new, under-development Type C connector, which is far smaller and designed for use with everything from laptops to mobile phones. The Type C connector is being touted as a single-cable solution for audio, video, data, and power. It will also have a reversible plug orientation. Lastly, will have bidirectional power delivery of up to 100 watts and power auto-negotiation. It is backward compatible with USB 3.0 and 2.0, but an adapter is needed for the physical connection.

Transmission Rates
USB 3.0: 4.8 Gbps
USB 2.0: 480 Mbps
USB 1.1: 12 Mbps

Cable Length/Node
5 meters (3 meters for 3.0 devices requiring higher speeds).
Devices/bus: 127
Tier/bus: 5
collapse


Black Box Explains... Industrial modem benefits.

Not all modems shuttle data in air-conditioned, climate-controlled comfort. And modems that operate in cozy environments have absolutely no business being exposed to harsh industrial conditions or to the elements.

But... more/see it nowjust because you work in a rough-and-tumble place doesn’t mean you have to sacrifice the convenience of a good modem. Instead, you should opt for an industrial modem. There are many industrial modems built for various degrees of extremity.

Survivability depends on reliability.
Sure, standard modems give you access to data in remote sites or enable you to service equipment on the plant floor—and you can do all this from the convenience of your office. However, these benefits are only possible if your modem can continue to function in its environment. And since standard modems aren’t built for adverse conditions, they’re not going to be reliable.

No penalties for interference.
Electrical control equipment—such as motors, relays, compressors, and generators—emit electromagnetic interference (EMI) that can affect the performance and reliability of a standard telephone modem.

EMI is emitted through power lines, the RS-232 communications cable, or through the telephone line itself. The very means of data communication, cable, is often the worst enemy of the standard modems that use it.

An industrial modem, on the other hand, has filters and superior EMI immunity to protect itself and your data. If you build your electrical cabinets to UL® or CSA standards, remember that your modem must also conform to UL® standard 508.

They go to extremes.
Temperature is the biggest killer of electronic equipment in industrial environments. The heat generated by industrial equipment in sealed enclosures or where space is a premium can make the temperature as much as 50 °F higher than the surrounding environment.

So standard modems can’t take the heat. But what about being outdoors in the other extreme, cold weather? Well, standard modems can’t take the cold either.

If you install your equipment in remote outdoor locations, it must work on the coldest days— especially those cold days when you least want to get in the car and go to the site to repair a standard modem that froze up.

Whether they’re placed in manufacturing environments or the great outdoors, industrial modems get the data through when you need it. They go to extremes for you.

Heavy metal for all kinds of banging around.
Industrial modems are built with durable metal enclosures that protect circuitry in rough conditions and ward off signal-disrupting EMI. Plus, they feature steel-bolt flanges to anchor them. In short, industrial modems can take the physical, heavy-duty punishment thrown their way.

So where exactly can you use an industrial modem?
• Heavy industry and manufacturing
• Oil and gas fields
• Refineries
• Storage sites
• Utility substations
• Agricultural projects
• Military facilities
• Research installations
• Water/wastewater systems

…and another thing!
If dedicated copper lines can’t be run through industrial environments, or if the fiber optic option is cost-prohibitive, there are also wireless industrial modems that make line-of-sight connections. If there’s a way to get the data through, industrial modems will get the job done.

Industrial-strength assurance.
Industrial modems remain in service for a very long time. But if you ever need a replacement that is hardware or software compatible, be assured that Black Box continues to support its products year after year—so you don’t spend your time re-engineering systems if you have to make a replacement. 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... Advantages of the MicroRACK system.

• Midplane architecture—Separate front and rear cards make changing interfaces easy.
• Multiple functions—Supports line drivers, interface converters, fiber modems, CSU/DSUs, and synchronous modem eliminators.
• Hot swappable—MicroRACK Cards can be replaced... more/see it nowwithout powering down, so you cut your network’s downtime.
• Two-, four-, and eight-port MicroRACKs—available for smaller or desktop installations. They’re just right for tight spaces that can’t accommodate a full-sized (16-port) rack.
• Optional dual cards—Some Mini Driver Cards have two drivers in one card. One MicroRACK chassis can hold up to 32 Mini Drivers!
• All standard connections available—DB25, RJ-11, RJ-45, fiber, V.35.
• Choose you own power supply—120–240 VAC, 12 VDC, 24 VDC, or 48 VDC. 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...Beyond T1—other standards for high-speed circuits.

While there are many applications for basic T1 rate service (1.536 Mbps), some applications require much more bandwidth. One of the most attractive features of T1 is the number of... more/see it nowoptions available to accommodate these kinds of demands. The important thing to remember is that all of these higher-speed services operate with the same consistent framing formats as the standard T1 service.

T1 is a high-speed service with a clock speed of 1.544 Mbps. It’s made up of 24 64-kbps DS0 (Digital-Signal [zero]) subchannels that together can support throughput rates of up to 1.536 Mbps. But there are higher levels of T1 service that are also available. For instance, T1C service doubles the T1 rate. It supports 3.152 Mbps with a total of 48 DS0s for top-speed applications. In a T1C environment, two T1 lines are combined into one using a special T1 mux.

The next-highest level of service is called T2. It offers 6.312 Mbps over 96 DS0s by multi-plexing 4 T1 lines into a single high-speed line.

The next two levels of service are exponentially larger than T2. A high-speed T3 trunk line is 28 times larger than a standard T1 line. T3 brings 44.736 Mbps to a customer site via 672 DS0s. This tremendous capacity is made possible by multiplexing 28 T1 lines or combina?tions of T2 and T1 lines.

Finally, T4 service offers a bandwidth potential of 274.176 Mbps, made up of 4032 64-kbps DS0 subchannels. At 168 times the size of a standard 1.544-Mbps line, T4 service dwarfs T1. The physical connections require multiplexing 6 T3 lines or 168 T1 lines into a single high-speed trunk.

With so many incredibly high-speed T-level service options available, system administrators have great flexibility to configure their operations for maximum efficiency and economy.

It’s important to remember that these various levels of T1 services can be implemented simultaneously within a particularly large enterprise to support complex network configurations.

Of course, this kind of application has the potential to become somewhat overwhelming from a management standpoint. However, as long as you keep track of the individual DS0s, you should always be able to accurately gauge how much available bandwidth you have at your disposal. 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

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