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The ANSI/ISA Standard and Hazardous Locations

Fires and explosions are a major safety concern in industrial plants. Electrical equipment that must be installed in these locations should be specifically designed and tested to operate under extreme... more/see it nowconditions. The hazardous location classification system was designed to promote the safe use of electrical equipment in those areas “where fire or explosion hazards may exist due to flammable gases or vapors, flammable liquids, combustible dust, or ignitable fibers of flyings.”

The NEC and CSA define hazardous locations by three classes:
Class 1: Gas or vapor hazards
Class 2: Dust hazards
Class 3: Fibers and flyings

Two divisions:
Division 1: An environment where ignitable gases, liquids, vapors or dusts can exist Division 2: Locations where ignitables are not likely to exist

Hazardous classes are further defined by groups A, B, C, D, E, F, and G:
A. Acetylene
B. Hydrogen
C. Ethlene, carbon monoxide
D. Hydrocarbons, fuels, solvents
E. Metals
F. Carbonaceous dusts including coal, carbon black, coke
G. Flour, starch, grain, combustible plastic or chemical dust

ANSI/ISA 12.12.01
Our line of Industrial Ethernet Switches (LEH1208A, LEH1208A-2GMMSC, LEH1216A and LEH1216A-2GMMSC) is fully compliant with ANSI/ISA 12.12.01, a construction standard for Nonincendive Electrical Equipment for Use in Class I and II, Division 2 and Class III, Divisions 1 and 2 Hazardous (Classified) Locations. ANSI/ISA 12.12.01-2000 is similar to UL1604, but is more stringent (for a full list of changes, see Compliance Today). UL1604 was withdrawn in 2012 and replaced with ISA 12.12.01.

The standard provides the requirements for the design, construction, and marking of electrical equipment or parts of such equipment used in Class I and Class II, Division 2 and Class III, Divisions 1 and 2 hazardous (classified) locations. This type of equipment, in normal operation, is not capable of causing ignition.

The standard establishes uniformity in test methods for determining the suitability of equipment as related to their potential to ignite to a specific flammable gas or vapor-in-air mixture, combustible dust, easily ignitable fibers, or flyings under the following ambient conditions:
a) an ambient temperature of -25°C to 40°C.
b) an oxygen concentration of not greater than 21 percent by volume.
c) a pressure of 80 kPa (0.8 bar) to 110 kPa (1.1 bar).

The standard is available for purchase at www.webstore.ansi.org. To learn more about ANSI/ISA 12.12.01 and hazardous location types, visit https://www.osha.gov/doc/outreachtraining/htmlfiles/hazloc.html. -- collapse

Black Box Explains...Upgrading from VGA to DVI video.

Many new PCs no longer have traditional Cathode Ray Tube (CRT) computer monitors with a VGA interface. The latest high-end computers have Digital Flat Panels (DFPs) with a Digital Visual... more/see it nowInterface (DVI). Although most computers still have traditional monitors, the newer DFPs are coming on strong because flat-panel displays are not only slimmer and more attractive on the desktop, but they’re also capable of providing a much sharper, clearer image than a traditional CRT monitor.

The VGA interface was developed to support traditional CRT monitors. The DVI interface, on the other hand, is designed specifically for digital displays and supports the high resolution, the sharper image detail, and the brighter and truer colors achieved with DFPs.

Most flat-panel displays can be connected to a VGA interface, even though using this interface results in inferior video quality. VGA simply can’t support the image quality offered by a high-end digital monitor. Sadly, because a VGA connection is possible, many computer users connect their DFPs to VGA and never experience the stunning clarity their flat-panel monitors can provide.

It’s important to remember that for your new DFP display to work at its best, it must be connected to a DVI video interface. You should upgrade the video card in your PC when you buy your new video monitor. Your KVM switches should also support DVI if you plan to use them with DFPs. collapse

Black Box Explains...4K

4K is a term to describe a maximum video resolution of 4096 x 2400 pixels. However, the most commonly used resolution is UHD (Ultra High Definition) at 3840 x 2160... more/see it nowpixels. This resolution basically allows for four full HD signals of 1920 x 1080 pixels to be displayed on a single screen. Unfortunately, the pure pixel count doesn't tell the complete the story. The following overview provides an examination of some key differences to provide users with a better understanding of potential requirements to help select suitable solutions.

Technical Details

  • Maximum resolution: 4096 x 2400, with 3840 x 2160 reflecting between 8.9 Megapixel and 9.8 Megapixel
  • Refresh rate: 24p/30p/60p

  • Typical Interfaces
    The DVI specification allows 1920 x 1200 pixels to be transmitted in single-link format or 2560 x 1600 (2048 x 2048) pixels in dual link. Typically, the single link is supported by 23- or 24-inch displays, commonly called Full HD panels. The dual-link resolutions require larger screen sizes of typically 27 inches (2560 x 1440), 30 inch (2560 x 1600), or square ATC displays of 2048 x 2048 pixels.

    Full 4K resolutions of 3840 x 2160 or higher over DVI dual link are possible, but only at less than 30 Hz due to bandwidth limitations. The bandwidth required for professional AV and PC environments can come to 4.95 Gbps (165 Mhz) for single link or 9.9 Gbps (2x 165 Mhz) for dual-link DVI.

    HDMI and DVI share the same digital video signal format, but HDMI 1.2 allows for higher pixel clock frequencies, resulting in higher bandwidth or resolutions and deeper color.

    The specifications vary based on the different HDMI versions. Up to HDMI 1.2 the specs more or less reflect those of DVI video. HDMI 1.3 and 1.4 exceed the dual-link DVI specs although it only uses a single link. HDMI 1.3/1.4 bandwidth is 10.2 Gbps (single link 140 Mhz).

    Most HDMI 4K appliances and displays currently on the market are limited to 30 Hz. The recently released HDMI 2.0 standard increases bandwidth to 18 Gpbs (600 Mhz), effectively matching the bandwidth of DisplayPort for supporting 4K at up to 60 fps. The first HDMI 2.0 displays supporting this full specification are presently showing up on the market. HDMI is commonly used on almost all consumer and professional AV equipment.

    DisplayPort 1.2
    DisplayPort is a slightly different, micro packet-based, video standard supporting a maximum bandwidth of approximately 17 Gbits. This currently makes it the only suitable single-connect option for full UHD (3840 x 2160) at 60 fps.

    DisplayPort is mainly used on PC graphic adapter cards. Note: all current graphics cards with DisplayPort support the full DisplayPort 1.2a specification of 5.4 Gbps per lane and therefore only support 30 fps rather than 60 fps 4K resolutions.

    Thunderbolt 1.0 is an Apple-only interface for multi-purpose use including video. Thunderbolt is compatible with DP 1.1 and capable of natively outputting DisplayPort signals. Thunderbolt 2.0 is needed to support 4K at 60Hz, and is compatible with DisplayPort 1.2.

    Different ways of delivering 4K
    Depending on the specifications of the equipment being used, a 4K signal may be delivered in the following ways:

    Full spec 60 fps
  • Display/projector with four single-link DVI interfaces and synchronized channels. Acts like a video wall in just a single large device.
  • Display/projector with two dual-link DVI interfaces and synchronized channels. Acts like a video wall in just a single large device.
  • Display/projector with either two dula-link DVI or HDMI 1.4 inputs. The term used to describe this method is Multiple Protocol Transport (MPT).
  • Display with either DisplayPort, Thunderbolt, or upcoming HDMI 2.0 full spec interfaces.

  • 4K @ 24/30 fps
  • Display/projector with either one dual-link DVI or HDMI 1.4 input. (MPT.)
  • Display with either DisplayPort, Thunderbolt or upcoming HDMI 2.0 full spec interfaces.
  • collapse

    Black Box Explains... RJ-48

    An RJ-48 plug is often mistaken for RJ-45. On the outside, the two look identical—both are housed in a miniature 8-position jack. The difference is in the pairing of the... more/see it nowwires.

    In RJ-48, two of the wires are for transmit, two are for receive, and two are for the drain. The last two wires are reserved for future use.

    There are three subsets within RJ-48: RJ-48C, RJ-48X, and RJ-48S.

    RJ-48C and RJ-48X are very similar. Both use lines 1, 2, 4, and 5 and connect T1 lines. The RJ-48C is more common. The difference is that RJ-48X connectors have shorting bars.

    RJ-48S uses lines 1, 2, 7, and 8. It connects 56K DDS lines. collapse

    Black Box Explains...UARTs at a glance.

    Universal Asynchronous Receiver/Transmitters (UARTs) are integrated circuits that convert bytes from the computer bus into serial bits for transmission. By providing surplus memory in a buffer, UARTs help applications overcome... more/see it nowthe factors that can hinder system performance, providing maximum throughput to high-performance peripherals without slowing down CPUs.

    Early UARTs such as 8250 and 16450 did not include buffering (RAM or memory). With the advent of higher-speed devices, the need for UARTs that could handle more data became critical. The first buffered UART was the 16550, which incorporates a 16-byte First In First Out (FIFO) buffer and provides greater throughput than its predecessors.

    Manufacturers have been developing enhanced UARTs that continue to increase performance standards. These faster chips provide improvements such as larger buffers and increased speeds. Here are the rates of today’s common UARTs:

    UART FIFO Buffer Rate Supported
    16550 16-byte 115.2 kbps
    16554 16-byte 115.2 kbps
    16650 32-byte 460.8 kbps (burst rate)
    16654 64-byte 460.8 kbps (burst rate)
    16750 64-byte 460.8 kbps (burst rate)
    16850 128-byte 460.8 kbps (sustained rate)
    16854 128-byte 460.8 kbps (sustained rate) collapse

    Black Box Explains…CAT6A UTP vs. F/UTP.

    CAT6A is currently the cable of choice for future-proofing cabling installations and for 10-GbE networks.

    There are two types of CAT6A cable, unshielded (UTP) and shielded (F/UTP). F/UTP denotes foiled/unshielded... more/see it nowtwisted pair and consists of four unshielded twisted pairs encased in an overall foil shield. This is not to be confused with an S/FTP (screened/foiled twisted pair) cable, which has four individually shielded twisted pairs encased in an overall braided shield.

    CAT6A UTP is constructed in a certain way to help eliminate crosstalk and ANEXT. (ANEXT is the measurement of the signal coupling between wire pairs in different and adjacent cables.) This includes larger conductors (23 AWG minimum), tighter twists, an extra internal airspace, an internal separator between the pairs, and a thicker outer jacket. These features also increase the outer diameter of the cable, typically to .35 inches in diameter, up from .25 inches for CAT6 cable. This increased diameter creates a greater distance between pairs in adjacent links, thus reducing the between-channel signal coupling. But CAT6A UTP cable is still affected by ANEXT.

    According to the standards, ANEXT can be improved by laying CAT6A UTP cable loosely in pathways and raceways with space between the cables. This contrasts to the tightly bundled runs of CAT6/5e cable we are used to. The tight bundles present a worst-case scenario of six cables around one, thus the center cable would be adversely affected by ANEXT. Testing for ANEXT is a complex and time-consuming process where all possible wire-pair combinations are checked. It can take up to 50 minutes to test one link in a bundle of 24 CAT6A UTP cables.

    CAT6A F/UTP denotes foiled/unshielded twisted pairs and consists of four unshielded twisted pairs encased in an overall foil shield. ANEXT, and the time needed to test for it, can be greatly reduced, if not eliminated completely, by using CAT6A F/UTP. The foil shield acts as a barrier preventing external EMI/RFI from coupling onto the twisted pairs. It also prevents data signals from leaking out of the cable, making the cable more difficult to tap and better for secure installations. Studies also have shown that CAT6A F/UTP cable provides significantly more headroom (as much as 20 dB) than CAT6A UTP in 10-GbE over copper systems.

    Bigger isn't always better.
    CAT6A UTP cable has an overall allowable diameter of 0.354 inches. CAT6A F/UTP cable has an average outside diameter of 0.265–0.30 inches. That’s smaller than the smallest CAT6A UTP cable. An increase in the outside diameter (O.D.) of 0.1 inch, from 0.25 inches to 0.35 inches for example, represents a 21% increase in fill volume. In general, CAT6A F/UTP cable provides a minimum of 35% more fill capacity that CAT6A UTP cable.

    Also because of its large diameter, CAT6A UTP requires a larger bend radius, more pathways, less dense patch panel connections, and extensive ANEXT testing.

    CAT6A F/UTP cable is actually easier to handle, requires less bend radius, and uses smaller pathways. In addition, innovations in connector technology has made terminating CAT6A F/UTP cable simpler. In terms of grounding, the requirements for both UTP and F/UTP cable fall under TIA/EIA J-STD-607-A Commercial Building Grounding (Earthing) and Bonding Requirements for Telecommunications.

    The advantages of CAT6A F/UTP vs. UTP
    In summary, there are a number of advantages of using CAT6A F/UTP over CAT6A UTP in 10-GbE networks.

    1. Shielding eliminates ANEXT and EMI/RFI problems and testing.
    2. Data line security is enhanced because of shielding.
    3. Lighter, slimmer cable provides higher port density.
    4. Smaller outside diameter cable is easier to handle and reduces installation costs.
    5. Shielded cable uses less space in conduits.

    For more information, see the CAT6A F/UTP vs. UTP: What You Need to Know white paper in the Resources section at blackbox.com. collapse

    Black Box Explains...Augmented Category 6 (CAT6A).

    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... more/see it nowCAT6 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 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.

    There are two types of CAT6a cable, UTP and F/UTP.


    Black Box Explains... Matrix video switches.

    Matrix switches enable computers to mix and match the output of multiple PCs on multiple video monitors.

    For instance, if your operation has four PCs and you want to display the... more/see it nowvideo on one monitor to the other three monitors, a matrix video switch is what you need to handle the job. Use matrix switches for:
    • Trade shows—Set up a wall of video to wow the senses of attendees.
    • Transportation schedules—Provide real-time updates of flights or deliveries on multiple screens.
    • Training demonstrations—Control each screen’s video to focus everyone’s attention on what’s important. collapse

    Black Box Explains...Code-operated and matrix switches.

    Code-operated and matrix switches from Black Box give you computer-controlled switching for a variety of applications.

    Code-operated switches
    BLACK BOX® Code-Operated Switches enable one device to control up to 64 connected devices,... more/see it nowdepending on the code-operated switch. For instance, you can use one modem—not eight—to control eight devices. Code-operated switches are ideal for applications that require remote switching for file sharing or monitoring. Use code-operated switches for:
    • Remote programming. Call in via remote sites to access servers, logic controllers, or any devices that require programming.
    • Diagnostics. From your master control room, you can probe servers and run diagnostics.

    Matrix switches
    Matrix switches enable more than one device to control other devices. Any port can connect to any port and perform more than one operation at a time independently. The code-operated switches talk to only one slave port at a time.

    For instance, if your operation has four computers that need to share two printers and one modem, a matrix switch is what you need to handle the job. Use matrix switches for:
    • Industrial applications. You can download instructions remotely to more than one programmable logic controller.
    • Data sharing. PCs or industrial devices can be connected—locally or remotely—to other PCs and industrial devices or for file swapping. collapse

    Black Box Explains...The 13W3 connector.

    The 13W3 connector, also called a 13C3 or DB13W3 connector, is an unusual connector that combines a 10-pin D-shell with three analog video conductors. It supports very-high-resolution analog video signals... more/see it nowand has been used by Sun Microsystems®, SGI, NeXt, Intergraph, and other manufacturers. Although 13W3 connectors from different manufacturers look the same, they may be pinned differently.

    Pinning for a standard Sun® 13W3 connector:
    A1: Red
    A2: Green/Gray
    A3: Blue
    1: Ground*
    2: Vertical Sync*
    3: Sense 2
    4: Sense Ground
    5: Composite Sync 
    6: Horizontal Sync*
    7: Ground*
    8: Sense 1
    9: Sense 0
    10: Composite Ground

    * Considered obsolete; may not be connected. collapse

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