The Universal Serial Bus or USB cable was developed around the idea that users should be able to run multiple peripherals on their computers without the hassle of physically installing boards, manually allocating system resources, individually configuring devices, and powering the computer up and down every time equipment needs change. With USB cable, up to 127 individual peripheral devices can be connected to a host computer using a single interface and a system of USB hubs. (See below for a diagram of a typical USB system.) Attaching a USB peripheral to your computer is as easy as plugging headphones into your Walkman. USB devices are automatically recognized and configured. They can draw power directly from the system, from an attached self-powered hub, or be connected to their own power supply.
USB provides two-way communication between the PC and peripheral devices, making it ideal for many I/O applications. Multiple devices can connect to a system using a series of USB hubs and repeaters. A single USB interface is attached to the motherboard. A Root Hub with up to seven additional ports can be integrated into the main interface, or it can be externally connected with a cable. Each of the seven hubs on the Root Hub can in turn be connected to seven hubs, etc. to a maximum of seven tiers and 127 ports. A unique feature of USB is that a peripheral device can have a hub built into it. This type of peripheral, called “compound devices,” are comprised of a function device and one or more hubs. For example, a USB keyboard can contain an additional USB port for a USB mouse.
USB is generally described as having a tiered star topology, however each device communicates with the host as if it had its own connection. This means that communication from the host centers around a set of hubs/devices, each of which in-turn serves as the center for another set of hubs/devices, etc. However, the hubs are transparent to the software and the devices are addressed individually. Cables are used to create point-to-point connections between devices and USB ports, or to connect one USB hub to another. The maximum cable length is five meters long. However, a repeater hub may be used to extend the distance between the peripheral and the host. There are also special USB repeaters that can be used to extend the connection even further.
The Root USB Hub is connected directly to the USB Host, and from there everything is done with cables. Two types of USB cables can be used with USB devices: Series A and Series B. Series B cables are limited to 3 meters in length and are for use with low-speed (1.5 Mbps) USB peripherals such as keyboards and mice. The UTP cable has a pair of 28 AWG wire stranded copper for data and one pair 20-28 AWG for power.
The Series A connector is for use with high speed (12 Mbps) devices, and can be up to 5 meters long. The more common of the two, it consists of one pair 20-28 AWG wire for power (VBUS is typically +5V at the source) and one 28 AWG twisted wire pair for data. The connector has a shielded housing, making it STP compliant.
One special feature of USB systems is that they can directly supply power to the peripherals and the hubs attached to them. It can also regulate power usage for peripherals that use independent power sources. USB devices are classified based on the amount of power they supply or require. Low Bus Power devices take all their power from the bus, but no more than 100mA at a time. High bus-powered devices also take all their power from the bus, but can draw up to 500mA at a time. Self-powered devices use an external power supply, but can draw up to 1mA from the host if necessary—such as in the case of a power failure.
Hubs can also be low, high or self powered. Power flows downstream in a USB system, which means that a self-powered hub can be used to power high- and low-powered peripheral devices located further down in the network. This power arrangement has both advantages and disadvantages. For desktop systems where power is not a problem, it is extremely convenient not to have to use a separate outlet for each peripheral connected to the PC. In notebooks where battery longevity is often a problem, it might be more advantageous to use peripheral devices that have their own power source.
USB Specification 1.1 was designed for low to medium speed applications running at less then 12 Mbits/sec. As such it is not suited for high-end data transfer such as high-speed back-ups to hard disks or CDs, high resolution color printing and interactive gaming. The recently released USB Specification 2.0 aims to upgrade the bus for high performance applications. The main difference between Specification 1.1 and 2.0 is that the latter provides for data transfer rates up to 480 Mbits/sec.
USB 2.0 is fully backward compatible with all older USB devices. It merely adds another device class—“high speed device.” The USB host controller determines the type of devices attached to it, and then treats them accordingly. In fact, a high-speed USB hub can be used for both high, full (12Mbps) and low (1.5Mbps) speed devices at the same time.
While still relatively new, many manufactures are starting to release 2.0 peripherals. Quatech’s serial USB adapters will remain USB 1.1 devices, as even the fastest serial communication is limited to 10Mbps—well within the range of a full speed device.
For low to medium speed data communication applications USB Specification 1.1 provides a clear usability advantage older bus types. USB peripherals are both Plug and Play and Hot Swappable devices. Further, USB cable is flexible enough to incorporate up to 127 individual devices into a single system using only one interface. And, unlike PCMCIA cards, where the board itself is subject to considerable wear from multiple insertions and extractions, USB devices use a connector cable which can be inserted and removed multiple times without consequence. Because of USB’s structure, it can potentially reduce system downtime considerably.
As a bus option designed for both desktop and portable use, USB can bridge the gap between desktop and portable peripherals, provided the new peripherals are designed in small enough form to be practical for portable systems, and provided they do not draw too heavily from a laptop’s limited battery power.
USB 2.0 with its considerably higher speeds rivals both board-level interfaces such as PCI and other interfaces such as Firewire. In fact, some computer companies are pushing for a PC standard that will no longer supply slots for plug-in boards, and will rely completely on USB and Firewire type devices.
USB’s major drawback is its inability to implement peripherals designed for older protocols. As USB popularity increases, it is becoming more likely that a USB device exists for any given application. However, software applications written for non-USB peripherals cannot be implemented using USB because of the difference in communication protocols. Quatech has solved this problem with our FreedomUSB serial adapters. With Quatech’s FreedomUSB Series you can take full advantage of USB benefits while continuing to use your current serial peripherals in your existing applications.
Optimize your space with our top of the line and versatile workbench solutions. Our systems are completely modular, allowing you to design the layout that is perfect for your environment.
Cable management and organization is easier than ever with cable trays built into the grames to help keep wiring tucked away. Additional addons, such as keyboard trays, utility drawers, and LCD monitor mounts make our solution the most comprehensive line available.
Don’t get buried.
Clean and tidy installations not only impress: they improve performance and reduce outages. Cables that are properly organized and tucked away are less susceptible to tangling, snagging, or other environmental damage. Likewise, reducing clutter improves airflow, thereby keeping your server rooms cooler.
The larger your installation, the more important it is to utilize proper cable management and workstation organization. With our wire and cable management solutions, you will have everything you need to keep your cables neat and organized. With superior grade products at the most competitive products, what are you waiting for?
Organize your installation today.
The best outlet is the one that goes unnoticed while offering plenty of ports. This is why we offer a full selection of wall plates from 1 to 6 ports in white, ivory, and almond.
Whether you wish to reduce visible cables by installing a series of 1 port wall plates along a wall or whether you wish to reduce the number of holes you have to cut into drywall by fitting 6 ports in one plate, we have the wall plate for you.
No wall plate is secure without a proper fitting drywall bracket. This is why we carry both single and double gang drywall mounting plates.
As our brackets are UL listed, you can be rest assured that the screw holes will be uniformly aligned, making installation hassle-free. Of course, each bracket comes with the screws necessary for installation.
For professional looking custom installations, specialty wall plates are essential. As such, in addition to our line of Keystone wall plates, we offer CAT3, VGA, and HDMI wall plates.
Step 1: Seat each wire in place according to
the color scheme map.
Step 2: Position the MIG+ keystone jack in the
Punch Down Tool.
Step 3: Compress the handle, wires will be
terminated and extra wires will be cut.
Step 4: Remove jack from tool snap on cover
and your termination is complete.
Telephone wiring for a phone outlet is typically either 1, 2 or 3 pairs (2, 4, or 6 conductor). Most cable nowadays is UTP (unshielded twisted pair). There may be instances where you may need to connect to or transpose from the old “quad” cable. The diagram below provides the transposition between these standards.
Usually the primary dial tone or talk circuit is wired to the center two pins (pins 3 & 4) and is the white/blue and blue/white pair (AKA: T1 & R1 – tip 1 and ring 1). A standard single line phone draws dial tone from these center pins.
The secondary circuit is wired to the two pins (pins 2 & 5) directly to the side of the center pins and is the white/orange and orange/white pair (AKA: T2 & R2 – tip 2 and ring 2). Depending on the application, the secondary circuit can either be the 2nd dial tone line on a two line phone, or the data/control circuit for an electronic key phone.
The third circuit is wired to the two pins (pins 1 & 6) on the outside and is the white/green and green/white pair (AKA: T3 & R3 – tip 3 and ring 3). Depending on the application, the third circuit can either be the 3rd dial tone line on a three line phone or an accessory circuit for an electronic key phone.
In telephony the terms that represent the conductors that compromise a circuit are known as “tip and ring”. These terms stem from the early days of telephony when operators made telephone connections using ¼” phono plugs similar to those used today for stereo headphones. The old systems also carried a third wire which was a ground. The “Tip” was the tip of the plug and was the positive (+) side of the circuit. The “Ring” was a conductive ring right behind the tip of the plug and was the negative (-) side of the circuit. Right behind the ring was the “Sleeve” which was the ground connection.
In the old days of telephony, USOC (pronounced U-sock) standards were used to simplify and standardize the various different wiring schemes for modular jacks.
The USOC standards consisted of many different Registered Jack Configurations which were abbreviated as “RJ” and had designations like RJ-11, RJ-12, etc. Today we still refer to modular jacks in the RJ designations but rarely use them to refer to a wiring standard that they were originally intended for. Even though it is technically incorrect, popular terminology today for the terms RJ-11, 12 or 14 refer to a 6 pin jack and RJ-45 refers to an 8 pin jack
The office telephone has come a long way.
Long gone are the days of a singular rotary office phone. Whether you’re routing 10, 20, 50, or more telephone lines through an office, Primus Cable carries the telephone cables and telco accessories you’ll need to get the job done.
As always, you can rely on our products to be of the highest quality and meet or exceed all your performance expectations.
Can your cables keep up? Ours can.
We carry a variety of Telco products for all your voice and data cabling needs.
Our 66 and 110 blocks are IDC, meaning that contacts are easily available from the block’s front, making installation easier. Securing your 66 blocks has never been easier with our terminal block brackets. Also, our Mushroom Wire Posts are ideal for use with our patch panels to organize wires. Simply inserting or removing our Block Metal Bridge Clips allows connections to be quickly be made or eliminated.
We offer a wide variety of CAT5E and CAT6 pre-wired Universal Box Cases. For your convenience, each box case features a PCB unshielded keystone jack already inside. Double sided adhesive is also included.
When it comes to signal clarity, any electrical interference is too much interference! And when it comes to installations, archaic termination procedures interfere by slowing you down. Ensure a clear transmission and lightning fast installations with our Shielded EZ-RJ45 Connectors.
Unsurpassed protection meets exceptional ease with our Shielded EZ-RJ45® Connectors. The fully shielded plugs feature an internal ground to preserve signal integrity. As always, the convenient pass-through design of our EZ® connectors ensures speedy and accurate cable terminations.
The EZ-RJ45® design allows the conductor wires to pass through the connector so the twists in each pair can be pulled closer to the contacts than conventional plugs. Maintaining the twists to the point of termination significantly decreases crosstalk and markedly increases performance.
Our fully shielded EZ-RJ45 Connectors reduce crosstalk and improve immunity to noise at all frequencies. Additionally, it is especially effective above 30 MHz, which is when cable balance tends to significantly degrade. The shielding also significantly improves Shannon capacity, which is the maximum amount of error-free digital data that can be transmitted in the presence of electrical interference.