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Black Box Explains...USB 2.0 and USB OTG.

The Universal Serial Bus (USB) hardware (plug-and-play) standard makes connecting peripherals to your computer easy.

USB 1.1, introduced in 1995, is the original USB standard. It has two data rates:... more/see it now12 Mbps for devices such as disk drives that need high-speed throughput and 1.5 Mbps for devices such as joysticks that need much lower bandwidth.

In 2002, a newer specification, USB 2.0, or Hi-Speed USB 2.0, gained wide acceptance in the industry. This version is both forward- and 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 CD/DVD burners, scanners, digital cameras, video equipment, and more. USB 2.0 supports demanding applications, such as Web publishing, in which multiple high-speed devices run simultaneously. USB 2.0 also supports Windows® XP through a Windows update.

An even newer USB standard, USB On-The-Go (OTG), is also in development. USB OTG enables devices other than a PC to act as a host. It enables portable equipment—such as PDAs, cell phones, digital cameras, and digital music players—to connect to each other without the need for a PC host.

USB 2.0 specifies three types of connectors: the A connector, the B connector, and the Mini B connector. A fourth type of connector, the Mini A (used for smaller peripherals such as mobile phones), was developed as part of the USB OTG specification. 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...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...RS-232.

RS-232, also known as RS-232C and TIA/EIA-232-E, is a group of electrical, functional, and mechanical specifications for serial interfaces between computers, terminals, and peripherals. The RS-232 standard was developed by... more/see it nowthe Electrical Industries Association (EIA), and defines requirements for connecting data communications equipment (DCE)—modems, converters, etc.—and data terminal equipment (DTE)—computers, controllers, etc.) devices. RS-232 transmits data at speeds up to 115 Kbps and over distances up to 50 feet (15.2 m).

The standard, which is functionally equivalent to ITU V.24/V.28, specifies the workings of the interface, circuitry, and connector pinning. Both sync and async binary data transmission fall under RS-232. Although RS-232 is sometimes still used to transmit data from PCs to peripheral devices, the most common uses today are for network console ports and for industrial devices.

Even though RS-232 is a “standard,” you can’t necessarily expect seamless communication between two RS-232 devices. Why? Because different devices have different circuitry or pinning, and different wires may be designated to perform different functions.

The typical RS-232 connector is DB25, but some PCs and other data communication devices have DB9 connectors and many newer devices have RJ-45 RS-232 ports. To connect 9-pin PC ports or RJ-45 to devices with 25-pin connectors, you will require a simple adapter cable. collapse


Black Box Explains...How computer speeds are enhanced with PCI buses and UARTs.

The Peripheral Component Interconnect (PCI®) Bus enhances both speed and throughput. The PCI Local Bus is a high-performance bus that provides a processor-independent data path between the CPU and high-speed... more/see it nowperipherals. PCI is a robust interconnect interface designed specifically to accommodate multiple high-performance peripherals for graphics, full-motion video, SCSI, and LANs.

UARTs (Universal Asynchronous Receiver/ Transmitters) are integrated circuits that convert bytes from the computer bus into serial bits for transmission. By providing surplus memory in a buffer, UARTs help your applications overcome the factors that slow down your system. collapse


Black Box Explains...IRQs, COM Ports, and Windows

Windows® 95 normally requires each serial port to have its own unique Interrupt Request Line (IRQ). However, if you use a third-party communications driver that supports IRQ sharing, you can... more/see it nowshare interrupts. Unfortunately, data throughput will not be as high as with single interrupt port configurations.

With Windows NT®, you can share interrupts across multiple ports as long as the serial ports have an Interrupt Status Port (ISP) built into the card.

The Interrupt Service Routine, a software routine that services interrupts and requests processor time, reads the ISP and is immmediately directed to the port that has an interrupt pending. Compared to the polling method used if the serial ports don’t have an ISP, this feature can determine which port generated the interrupt up to four times more efficiently—and it almost eliminates the risk of lost data. Windows NT supports the ISP by enabling the user to configure the registry to match the card’s settings. Black Box models IC102C-R3, IC058C, and IC112C-R3 all have ISPs and come with a Windows NT setup utility to simplify installation and configuration.

If your serial port doesn’t have an ISP, the Interrupt Service Routine has to poll each port separately to determine which port generated the interrupt. collapse


Black Box Explains... G.703.

G.703 is the ITU-T recommendation covering the 4-wire physical interface and digital signaling specification for transmission at 2.048 Mbps (E1). G.703 also includes specifications for U.S. 1.544-Mbps T1 but is... more/see it nowstill generally used to refer to the European 2.048-Mbps transmission interface. collapse


Black Box Explains...V.35, the Faster Serial Interface.

V.35 is the ITU (formerly CCITT) standard termed “Data Transmission at 48 kbps Using 60–108 KHz Group-Band Circuits.“

Basically, V.35 is a high-speed serial interface designed to support both higher data... more/see it nowrates and connectivity between DTEs (data-terminal equipment) or DCEs (data-communication equipment) over digital lines.

Recognizable by its blocky, 34-pin connector, V.35 combines the bandwidth of several telephone circuits to provide the high-speed interface between a DTE or DCE and a CSU/DSU (Channel Service Unit/Data Service Unit).

Although it’s commonly used to support speeds ranging anywhere from 48 to 64 kbps, much higher rates are possible. For instance, maximum V.35 cable distances can theoretically range up to 4000 feet (1200 m) at speeds up to 100 kbps. Actual distances will depend on your equipment and cable.

To achieve such high speeds and great distances, V.35 combines both balanced and unbalanced voltage signals on the same interface. collapse


Black Box Explains... Single-Mode Fiber Optic Cable

Multimode fiber cable has multiple modes of propagation—that is, several wavelengths of light are normally used in the fiber core. In contrast, single-mode fiber cable has only one mode of... more/see it nowpropagation: a single wavelength of light in the fiber core. This means there’s no interference or overlap between the different wavelengths of light to garble your data over long distances like there is with multimode cable.

What does this get you? Distance–up to 50 times more distance than multimode fiber cable. You can also get higher bandwidth. You can use a pair of single-mode fiber strands full-duplex for up to twice the throughput of multimode fiber cable. The actual speed and distance you get will vary with the devices used with the single-mode fiber. collapse


Black Box Explains... Spread Spectrum wireless technology.

Frequency-Hopping Spread Spectrum wireless communication provides error-free transmission, top security, and high levels of throughput without the need for an FCC site license. The key to Spread Spectrum is a... more/see it nowfrequency-hopping transceiver.

Narrow-band frequency hoppers use a predefined algorithm to maintain synchronization and high throughput between master and remote modems. They achieve this by continually switching or “hopping” from one transmission frequency to another throughout the Spread Spectrum band. The sequence of frequencies is very difficult to predict and thus nearly impossible to eavesdrop on or jam. If interference is encountered at any particular frequency, the built-in error correction detects it and resends the data packet at the next frequency hop. Because EMI/RFI interference rarely affects the entire available bandwidth, and each frequency hop is at least 6 MHz, the radio transmitter has access to as many as 100 frequencies within the spectrum to avoid interference and ensure that data gets through. collapse

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