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Black Box Explains...16850 UART.

The 16850 Universal Asynchronous Receiver/Transmitter (UART) features a 128-byte First In First Out (FIFO) buffer. When implemented with the appropriate onboard drivers and receivers, it enables your onboard serial ports... more/see it nowto achieve sustained data rates of up to 460.8 kbps.

The 16850 UART includes automatic handshaking (RTS/CTS) and automatic RS-485 line control. It also features external clocking for isochronous applications, a performance enhancement not offered by earlier UARTs. collapse


Black Box Explains...Category wiring standards

The ABCs of standards
There are two primary organizations dedicated to developing and setting structured cabling standards. In North America, standards are issued by the Telecommunications Industry Association (TIA),... more/see it nowwhich is accredited by the American National Standards Institute (ANSI). The TIA was formed in April 1988 after a merger with the Electronics Industry Association (EIA). That’s why its standards are commonly known as ANSI/TIA/EIA, TIA/EIA, or TIA.

Globally, the organizations that issue standards are the International Electrotechnical Commission (IEC) and the International Organization for Standardization (ISO). Standards are often listed as ISO/IEC. Other organizations include the Canadian Standards Association (CSA), CENELEC (European Committee for Electrotechnical Standardizations), and the Japanese Standards Association (JSA/JSI).

The committees of all these organizations work together and the performance requirements of the standards are very similar. But there is some confusion in terminology.

The TIA cabling components (cables, connecting hardware, and patch cords) are labeled with a ”category.” These components together form a permanent link or channel that is also called a ”category.” The ISO/IEC defines the link and channel requirements with a ”class” designation. But the components are called a ”category.”

The standards
Category 5 (CAT5) —ratified in 1991. It is no longer recognized for use in networking.

Category 5e (CAT5e), ISO/IEC 11801 Class D, ratified in 1999, is designed to support full-duplex, 4-pair transmission in 100-MHz applications. The CAT5e standard introduced the measurement for PS-NEXT, EL-FEXT, and PS-ELFEXT. CAT5e is no longer recognized for new installations. It is commonly used for 1-GbE installations.

Category 6 (CAT6) – Class E has a specified frequency of 250 MHz, significantly improved bandwidth capacity over CAT5e, and easily handles Gigabit Ethernet transmissions. CAT6 supports 1000BASE-T and, depending on the installation, 10GBASE-T (10-GbE).

10-GbE over CAT6 introduces Alien Crosstalk (ANEXT), the unwanted coupling of signals between adjacent pairs and cables. Because ANEXT in CAT6 10-GbE networks is so dependent on installation practices, TIA TSB-155-A and ISO/IEC 24750 qualifies 10-GbE over CAT6 over channels of 121 to 180 feet (37 to 55 meters) and requires it to be 100% tested, which is extremely time consuming. To mitigate ANEXT in CAT6, it is recommended that the cables be unbundled, that the space between cables be increased, and that non-adjacent patch panel ports be used. If CAT6 F/UTP cable is used, mitigation is not necessary and the length limits do not apply. CAT6 is not recommended for new 10-GbE installations.

Augmented Category 6 (CAT6A) –Class Ea was ratified in February 2008. This standard calls for 10-Gigabit Ethernet data transmission over a 4-pair copper cabling system up to 100 meters. CAT6A extends CAT6 electrical specifications from 250 MHz to 500 MHz. It introduces the ANEXT requirement. It also replaces the term Equal Level Far-End Crosstalk (ELFEXT) with Attenuation to Crosstalk Ratio, Far-End (ACRF) to mesh with ISO terminology. CAT6A provides improved insertion loss over CAT6. It is a good choice for noisy environments with lots of EMI. CAT6A is also well-suited for use with PoE+.

CAT6A UTP cable is significantly larger than CAT6 cable. It features larger conductors, usually 22 AWG, and is designed with more space between the pairs to minimize ANEXT. The outside diameter of CAT6A cable averages 0.29"–0.35" compared to 0.21"–0.24" for CAT6 cable. This reduces the number of cables you can fit in a conduit. At a 40% fill ratio, you can run three CAT6A cables in a 3/4" conduit vs. five CAT6 cables.

CAT6A UTP vs. F/UTP. Although shielded cable has the reputation of being bigger, bulkier, and more difficult to handle and install than unshielded cable, this is not the case with CAT6A F/UTP cable. It is actually easier to handle, requires less space to maintain proper bend radius, and uses smaller conduits, cable trays, and pathways. CAT6A UTP has a larger outside diameter than CAT6A F/UTP cable. This creates a great difference in the fill rate of cabling pathways. An increase in the outside diameter of 0.1", from 0.25" to 0.35" for example, represents a 21% increase in fill volume. In general, CAT6A F/UTP provides a minimum of 35% more fill capacity than CAT6A UTP. In addition, innovations in connector technology have made terminating CAT6A F/UTP actually easier than terminating bulkier CAT6A UTP.

Category 7 (CAT7) –Class F was published in 2002 by the ISO/IEC. It is not a TIA recognized standard and TIA plans to skip over it.

Category 7 specifies minimum performance standards for fully shielded cable (individually shielded pairs surrounded by an overall shield) transmitting data at rates up to 600 MHz. It comes with one of two connector styles: the standard RJ plug and a non-RJ-style plug and socket interface specified in IEC 61076-2-104:2.

Category 7a (CAT7a) –Class Fa (Amendment 1 and 2 to ISO/IEC 11801, 2nd Ed.) is a fully shielded cable that extends frequency from 600 MHz to 1000 MHz.

Category 8 – The TIA decided to skip Category 7 and 7A and go to Category 8. The TR-42.7 subcommittee is establishing specs for a 40-Gbps twisted-pair solution with a 2-GHz frequency. The proposed standard is for use in a two-point channel in a data center at 30 meters. It is expected to be ratified in February 2016. The TR-42.7 subcommittee is also incorporating ISO/IEC Class II cabling performance criteria into the standard. It is expected to be called TIA-568-C.2-1. The difference between Class I and Class II is that Class II allows for three different styles of connectors that are not compatible with one another or with the RJ-45 connector. Class I uses an RJ-45 connector and is backward compatible with components up to Category 6A. 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...Ceramic and composite ferrules.

Cables manufactured with ceramic ferrules are ideal for mission-critical applications or connections that are changed frequently. These cables are high quality and typically have a very long life. Ceramic ferrules... more/see it noware more precisely molded and fit closer to the fiber than their composite counterparts, which gives them a lower optical loss.

On the other hand, cables with composite ferrules are ideal for less critical applications or connections that won’t be changed frequently. Composite ferrule cables are characterized by low loss, good quality, and long life. collapse


Black Box Explains...Cable termination.

STEP 1
Carefully remove the jacketing from the cable and expose one inch of the insulated wire conductors. Do not remove any insulation from the conductors. When the RJ-45 connector is... more/see it nowcrimped, the contacts inside will pierce the conductor insulation.

STEP 2
Untwist the wires to within 1/8" of the jacket. Arrange the wires according to the cable spec (568B in this case). Flatten and align the wires. Make one straight cut across all the conductors, removing approximately 1/2" to ensure the ends are of equal length.

STEP 3
Slide the wires into a connector. The cable jacket should extend into the connector about 1/4" for strain relief. Orient the wires so connector Pin 1 aligns with cable Pin 1, etc. Hold the connector in front of you. With the locking tab down, Pin 1 is on the far left.

STEP 4
Insert the connector into a crimp tool. Make sure you’re using the proper die. Firmly squeeze the handles. They’ll lock in a ratcheting action. A final click indicates the connector is firmly latched.

STEP 5
Check your work using a continuity tester or cable certifier rated for the cable standard you’re installing. Your tester should be able to check for shorts, opens, or miswires.

Wiring Standards collapse


Black Box Explains...Digital Visual Interface (DVI) and other digital display interfaces.

There are three main types of digital video interfaces: P&D, DFP, and DVI. P&D (Plug & Display, also known as EVC), the earliest of these technologies, supports both digital and... more/see it nowanalog RGB connections and is now used primarily on projectors. DFP (Digital Flat-Panel Port) was the first digital-only connector on displays and graphics cards; it’s being phased out.

There are different types of DVI connectors: DVI-D, DVI-I, DVI-A, DFP, and EVC.

DVI-D is a digital-only connector. DVI-I supports both digital and analog RGB connections. Some manufacturers are offering the DVI-I connector type on their products instead of separate analog and digital connectors. DVI-A is used to carry an analog DVI signal to a VGA device, such as a display. DFP, like DVI-D, was an early digital-only connector used on some displays; it’s being phased out. EVC (also known as P&D) is similar to DVI-I only it’s slightly larger in size. It also handles digital and analog connections, and it’s used primarily on projectors.

All these standards are based on transition-minimized differential signaling (TMDS). In a typical single-line digital signal, voltage is raised to a high level and decreased to a low level to create transitions that convey data. TMDS uses a pair of signal wires to minimize the number of transitions needed to transfer data. When one wire goes to a high-voltage state, the other goes to a low-voltage state. This balance increases the data-transfer rate and improves accuracy. collapse


Black Box Explains...Gigabit Ethernet.

As workstations and servers migrated from ordinary 10-Mbps Ethernet to 100-Mbps speeds, it became clear that even greater speeds were needed. Gigabit Ethernet was developed for an even faster Ethernet... more/see it nowstandard to handle the network traffic generated on the server and backbone level by Fast Ethernet. Gigabit Ethernet delivers an incredible 1000 Mbps (or 1 Gbps), 100 times faster than 10BASE-T. At that speed, Gigabit Ethernet can handle even the traffic generated by campus network backbones. Plus it provides a smooth upgrade path from 10-Mbps Ethernet and 100-Mbps Fast Ethernet at a reasonable cost.

Compatibility
Gigabit Ethernet is a true Ethernet standard. Because it uses the same frame formats and flow control as earlier Ethernet versions, networks readily recognize it, and it’s compatible with older Ethernet standards. Other high-speed technologies (ATM, for instance) present compatibility problems such as different frame formats or different hardware requirements.

The primary difference between Gigabit Ethernet and earlier implementations of Ethernet is that Gigabit Ethernet almost always runs in full-duplex mode, rather than the half-duplex mode commonly found in 10- and 100-Mbps Ethernet.

One significant feature of Gigabit Ethernet is the improvement to the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) function. In half-duplex mode, all Ethernet speeds use the CSMA/CD access method to resolve contention for shared media. For Gigabit Ethernet, CSMA/CD has been enhanced to maintain the 200-meter (656.1-ft.) collision diameter.

Affordability and adaptability
You can incorporate Gigabit Ethernet into any standard Ethernet network at a reasonable cost without having to invest in additional training, cabling, management tools, or end stations. Because Gigabit Ethernet blends so well with your other Ethernet applications, you have the flexibility to give each Ethernet segment exactly as much speed as it needs—and if your needs change, Ethernet is easily adaptable to new network requirements.

Gigabit Ethernet is the ideal high-speed technology to use between 10-/100-Mbps Ethernet switches or for connection to high-speed servers with the assurance of total compatibility with your Ethernet network.

When Gigabit Ethernet first appeared, fiber was crucial to running Gigabit Ethernet effectively. Since then, the IEEE802.3ab standard for Gigabit over Category 5 cable has been approved, enabling short stretches of Gigabit speed over existing copper cable. Today, you have many choices when implementing Gigabit Ethernet:

1000BASE-X
1000BASE-X refers collectively to the IEEE802.3z standards: 1000BASE-SX, 1000BASE-LX, and 1000BASE-CX.

1000BASE-SX
The “S“ in 1000BASE-SX stands for “short.“ It uses short wavelength lasers, operating in the 770- to 860-nanometer range, to transmit data over multimode fiber. It’s less expensive than 1000BASE-LX, but has a much shorter range of 220 meters over typical 62.5-µm multimode cable.

1000BASE-LX
The “L“ stands for “long.“ It uses long wavelength lasers operating in the wavelength range of 1270 to 1355 nanometers to transmit data over single-mode fiber optic cable. 1000BASE-LX supports up to 550 meters over multimode fiber or up to 10 kilometers over single-mode fiber.

1000BASE-CX
The “C“ stands for “copper.“ It operates over special twinax cable at distances of up to 25 meters. This standard never really caught on.

Gigabit over CAT5—1000BASE-TX
The 802.3ab specification, or 1000BASE-TX, enables you to run IEEE-compliant Gigabit Ethernet over copper twisted-pair cable at distances of up to 100 meters of CAT5 or higher cable.

Gigabit Ethernet uses all four twisted pairs within the cable, unlike 10BASE-T and 100BASE-TX, which only use two of the four pairs. It works by transmitting 250 Mbps over each of the four pairs in 4-pair cable. collapse


Black Box Explains...Optical isolation and ground loops.

Optical isolation protects your equipment from dangerous ground loops. A ground loop is a current across a conductor, created by a difference in potential between two grounded points, as in... more/see it nowequipment in two buildings connected by a run of RS-232 or other data line. When two devices are connected and their potentials are different, voltage flows from high to low by traveling through the data cable. If the voltage potential is large enough, your equipment won’t be able to handle the excess voltage and one of your ports will be damaged.

Ground loops can also exist in industrial environments. They can be created when power is supplied to your equipment from different transformers or when someone simply turns equipment on and off. Ground loops can also occur when there is a nearby lightning strike. During an electrical storm, the ground at one location can be charged differently than the other location, causing a heavy current flow through the serial communication lines that damage components.

You can’t test for ground loops. You don’t know you have one until a vital component fails. Only prevention works. For data communication involving copper cable, optical isolation is key.

With optical isolation, electrical data is converted to an optical beam, then back to an electrical pulse. Because there is no electrical connection between the DTE and DCE sides, an optical isolator— unlike a surge suppressor—will not pass large sustained power surges through to your equipment. Since data only passes through the optical isolator, your equipment is protected against ground loops and other power surges. collapse


Fiber optic cable construction and types.

Multimode vs. single-mode
Multimode cable has a large-diameter core and multiple pathways of light. It is most commonly available in two core sizes: 50-micron and 62.5-micron.

Multimode fiber optic cable can... more/see it nowbe used for most general data and voice fiber applications such as adding segments to an existing network, and in smaller applications such as alarm systems and bringing fiber to the desktop. Both multimode cable cores use either LED or laser light sources.

Multimode 50-micron cable is recommended for premise applications?(backbone, horizontal, and intrabuilding connections). It should be considered for any new construction and for installations because it provides longer link lengths and/or higher speeds, particularly in the 850-nm wavelength, than 62.5-micron cable does.

Multimode cable commonly has an orange or aqua jacket; single-mode has yellow. Other colors are available for various applications and for identification purposes.

Single-mode cable has a small (8–10-micron) glass core and only one pathway of light. With only a single wavelength of light passing through its core, single-mode cable realigns the light toward the center of the core instead of simply bouncing it off the edge of the core as multimode does.

Single-mode cable provides 50 times more distance than multimode cable does. Consequently, single-mode cable is typically used in high-bandwidth applications and in long-haul network connections spread out over extended areas, including cable television and campus backbone applications. Telcos use it for connections between switching offices. Single-mode cable also provides higher bandwidth, so you can use a pair of single-mode fiber strands full-duplex at more than twice the throughput of multimode fiber.

Construction
Fiber optic cable consists of a core, cladding, coating, buffer strengthening fibers, and cable jacket.

The core is the physical medium that transports optical data signals from an attached light source to a receiving device. It is a single continuous strand of glass or plastic that’s measured (in microns) by the size of its outer diameter.

All fiber optic cable is sized according to its core’s outer diameter. The two multimode sizes most commonly available are 50 and 62.5 microns. Single-mode cores are generally less than 9 microns.

The cladding is a thin layer that surrounds the fiber core and serves as a boundary that contains the light waves and causes the refraction, enabling data to travel throughout the length of the fiber segment.

The coating is a layer of plastic that surrounds the core and cladding to reinforce the fiber core, help absorb shocks, and provide extra protection against excessive cable bends. These coatings are measured in microns (µ); the coating is 250µ and the buffer is 900µ.

Strengthening fibers help protect the core against crushing forces and excessive tension during installation. This material is generally Kevlar® yarn strands within the cable jacket.

The cable jacket is the outer layer of any cable. Most fiber optic cables have an orange jacket, although some types can have black, yellow, aqua or other color jackets. Various colors can be used to designate different applications within a network.

Simplex vs. duplex patch cables
Multimode and single-mode patch cables can be simplex or duplex.

Simplex has one fiber, while duplex zipcord has two fibers joined with a thin web. Simplex (also known as single strand) and duplex zipcord cables are tight-buffered and jacketed, with Kevlar strength members.

Because simplex fiber optic cable consists of only one fiber link, you should use it for applications that only require one-way data transfer. For instance, an interstate trucking scale that sends the weight of the truck to a monitoring station or an oil line monitor that sends data about oil flow to a central location.

Use duplex multimode or single-mode fiber optic cable for applications that require simultaneous, bidirectional data transfer. Workstations, fiber switches and servers, Ethernet switches, backbone ports, and similar hardware require duplex cable.

PVC (riser) vs. plenum-rated
PVC cable (also called riser-rated cable even though not all PVC cable is riser-rated) features an outer polyvinyl chloride jacket that gives off toxic fumes when it burns. It can be used for horizontal and vertical runs, but only if the building features a contained ventilation system. Plenum can replace PVC, but PVC cannot be used in plenum spaces.

“Riser-rated” means that the jacket is fire-resistant. However, it can still give off noxious fumes when overheated. The cable carries an OFNR rating and is not for use in plenums.

Plenum-jacketed cables have FEP, such as Teflon®, which emits less toxic fumes when it burns. A plenum is a space within the building designed for the movement of environmental air. In most office buildings, the space above the ceiling is used for the HVAC air return. If cable goes through that space, it must be “plenum-rated.”

Distribution-style vs. breakout-style
Distribution-style cables have several tight-buffered fibers bundled under the same jacket with Kevlar or fiberglass rod reinforcement. These cables are small in size and are typically used within a building for short, dry conduit runs, in either riser or plenum applications. The fibers can be directly terminated, but because the fibers are not individually reinforced, these cables need to be terminated inside a patch panel, junction box, fiber enclosure, or cabinet.

Breakout-style cables are made of several simplex cables bundled together, making a strong design that is larger than distribution cables. Breakout cables are suitable for riser and plenum applications.

Loose-tube vs. tight-buffered
Both loose-tube and tight-buffered cables contain some type of strengthening member, such as aramid yarn, stainless steel wire strands, or even gel-filled sleeves. But each is designed for very different environments.

Loose-tube cable is specifically designed for harsh outdoor environments. It protects the fiber core, cladding, and coating by enclosing everything within semi-rigid protective sleeves or tubes. Many loose-tube cables also have a water-resistant gel that surrounds the fibers. This gel helps protect them from moisture, so the cables are great for harsh, high-humidity environments where water or condensation can be a problem. The gel-filled tubes can also expand and contract with temperature changes. Gel-filled loose-tube cable is not the best choice for indoor applications.

Tight-buffered cable, in contrast, is optimized for indoor applications. Because it’s sturdier than loose-tube cable, it’s best suited for moderate-length LAN/WAN connections, or long indoor runs. It’s easier to install as well, because there’s no messy gel to clean up and it doesn’t require a fan-out kit for splicing or termination.

Indoor/outdoor cable
Indoor/outdoor cable uses dry-block technology to seal ruptures against moisture seepage and gel-filled buffer tubes to halt moisture migration. Comprised of a ripcord, core binder, a flame-retardant layer, overcoat, aramid yarn, and an outer jacket, it is designed for aerial, duct, tray, and riser applications.

Interlocking armored cable
This fiber cable is jacketed in aluminum interlocking armor so it can be run just about anywhere in a building. Ideal for harsh environments, it is rugged and rodent resistant. No conduit is needed, so it’s a labor- and money-saving alternative to using innerducts for fiber cable runs.

Outside-plant cable is used in direct burials. It delivers optimum performance in extreme conditions and is terminated within 50 feet of a building entrance. It blocks water and is rodent-resistant.

Interlocking armored cable is lightweight and flexible but also extraordinarily strong. It is ideal for out-of-the-way premise links.

Laser-optimized 10-Gigabit cable
Laser-optimized multimode fiber cable assemblies differ from standard multimode cable assemblies because they have graded refractive index profile fiber optic cable in each assembly. This means that the refractive index of the core glass decreases toward the outer cladding, so the paths of light towards the outer edge of the fiber travel quicker than the other paths. This increase in speed equalizes the travel time for both short and long light paths, ensuring accurate information transmission and receipt over much greater distances, up to 300 meters at 10 Gbps.

Laser-optimized multimode fiber cable is ideal for premise networking applications that include long distances. It is usually aqua colored.

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Black Box Explains...Straight-pinned and crossover cable.

Straight-pinned cable has the most common type of pinning. The send and receive pairs are wired straight-through on either end of the cable.

Crossover cable is generally used for peer-to-peer connections.... more/see it nowThe send and receive pairs are crossed between Connector A to Connector B on either end of the cable. collapse

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