utp cable 5e what. Selecting the category of utp cable twisted pair to create the Internet

twisted pair It is used as a transmission medium in all modern network technologies, as well as in analog and digital telephony. The unification of passive elements of a twisted pair network has become the basis for the concept of building structured cabling systems that are independent of applications (network technologies). All twisted-pair networks (except the legacy LocalTalk) are based on a star-shaped physical topology, which, with the right active equipment, can serve as the basis for any logical topology.

Twisted pair or twisted pair cables (Twisted Pair cable or TP), unlike coaxial cable, are symmetrical and are used for differential (balanced) signal transmission. A twisted pair of wires differs significantly in properties from a pair of the same straight wires running side by side parallel to each other. When twisting, it turns out that the conductors always go at a certain angle to each other, which reduces the capacitive and inductive coupling between them. In addition, a significant segment of such a cable for external fields turns out to be symmetrical (round), which reduces its sensitivity to interference and external radiation during signal transmission. The smaller the twist pitch, the less crosstalk, but also the greater the per unit attenuation of the cable, as well as the signal propagation time. The cable can be of various designs, individual pairs can be screened with copper wire and/or foil. All cable pairs can also be enclosed in a common shield. For the first time in network technologies, twisted pair was used in Token Ring networks - the so-called IBM STP Type 1 cable. It was (and is) an expensive and bulky cable that requires rather large connectors. Currently, twisted pair cables are constantly being improved, mainly in the direction of expanding the bandwidth. 100 MHz is already a common value for cable bandwidth, standards are being developed for cables with a bandwidth of up to 600 MHz.

A twisted pair wire consists of two twisted insulated conductors. Such a wire is used for cross-wires inside wiring closets or racks, but not for laying connections between rooms. The crossover wire can consist of one, two, three or even four twisted pairs. The cable differs from the wire by the presence of an external insulating stocking (jacket). This stocking mainly protects the wires (cable elements) from mechanical stress and moisture. The most widely used cables contain two or four twisted pairs. There are cables for a large number of pairs - 25 pairs or more. Cord (cord) is a piece of flexible (stranded) cable of relatively short length. A typical example is a patch cord (patch cord) - a piece of stranded 4-pair. cable length 1-5 m with modular 8-pin plugs (RJ-45) at the ends.

Twisted Pair Categories

Category (Category) twisted pair determines the frequency range in which its use is effective (ACR is positive). There are currently standard definitions for 7 cable categories (CAT1...CAT7). The categories are defined by the EIA/TIA 568A standard.

• CAT1- (frequency band 0.1 MHz) telephone cable, only one pair, known in Russia as "noodles". In the USA it was used earlier, and the conductors were twisted together. Used only for voice or data transmission using a modem.
• CAT2- (frequency band 1 MHz) old type of cable, 2 pairs of conductors, supported data transfer at speeds up to 4 Mbps, used in Token Ring and ARCnet networks. Now sometimes found in telephone networks.
• CAT3- (frequency band 16 MHz) 2-pair cable, used in the construction of local networks 10BASE-T and Token Ring, only supports data transfer rates up to 10 Mbps. Unlike the previous two, it meets the requirements of the IEEE 802.3 standard. Also still found in telephone networks.
• CAT4- (frequency band 20 MHz) cable consists of 4 twisted pairs, used in token ring, 10BASE-T, 10BASE-T4 networks, data transfer rate does not exceed 16 Mbps, is not used now.
• CAT5- (frequency band 100 MHz) 4-pair cable, this is what is usually called a "twisted pair" cable, due to its high transmission speed, up to 100 Mbps when using 2 pairs and up to 1000 Mbps, when using 4 pairs, it is the most common network carrier used in computer networks so far. When laying new networks, a slightly improved CAT5e cable (125 MHz frequency band) is used, which better transmits high-frequency signals.
• CAT6- (frequency band 250 MHz) is used in Fast Ethernet and Gigabit Ethernet networks, consists of 4 pairs of conductors and is capable of transmitting data at speeds up to 10000 Mbps. Added to the standard in June 2002. There is a category CAT6a, in which the frequency of the transmitted signal is increased to 500 MHz.
• CAT7- data transfer rate 10000 Mbps, signal transmission frequency up to 600-700 MHz. This category of cable is shielded. Thanks to the double shield, the cable length can exceed 100 m.

Types of cable twisted pair

In addition to the generally accepted designations of cables by category, there is also a classification of cables by type (Type), introduced by IBM.

Twisted pair can be either shielded (shielded) or unshielded (unshielded). The terminology of screen designs is ambiguous, the words braid (braid), shield and screen (screen, protection), foil (foil), tinned drain wire (tinned “drain” wire running along the foil and slightly wrapping it around) are used here.

Unshielded twisted pair(NVP) is better known by its acronym UTP(Unshielded Twisted Pair). If the cable is enclosed in a common shield, but the pairs do not have individual shields, but, according to the standard (ISO 11801), it also belongs to unshielded twisted pairs and is designated UTP or S / UTP. This also includes STP (Screened Twisted Pair) or FTP (Foiled Twisted Pair) - a cable in which twisted pairs are enclosed in a common foil shield, as well as SFTP (Shielded Foil Twisted Pair) - a cable in which the common shield consists of foil and braids.

Shielded twisted pair(EVP), she STP(Shielded Twisted Pair), has many varieties, but each pair must have its own screen:

• STP with a designation like "Type xx" is a "classic" twisted pair cable introduced by IBM for TokenRing networks. Each pair of this cable is enclosed in a separate foil screen (except type 6A), both pairs are enclosed in a common braided wire screen, outside, everything is covered with an insulating stocking, impedance - 150 ohms. Wire can be 22-26 AWG solid or stranded. Single core 22 AWG cable can have a bandwidth of up to 300 MHz.
• Category 5 STP is a common name for a 100 ohm impedance cable that has a separate shield for each pair, which can be of various designs (foil, braid, combination of both). Sometimes under the same name there is a cable that has only a common screen (AMP company),
• SSTP (Shielded- Screened Twisted Pair) category 7 - a cable similar to PiMF.

Cables can have different impedance ratings. The EIA/TIA-568A standard defines two values ​​- 100 and 150 ohms, standards IS01 1801 and EN 50173 add 120 ohms. Requirements for impedance accuracy in the operating frequency band are usually in the range of ±15% of nominal. Note that UTP cable most often has an impedance of 100 ohms, and shielded STP cable originally existed only with an impedance of 150 ohms. Currently, there are types of shielded cable with an impedance of 100 and 120 ohms. Terminal equipment is available in versions for both shielded (STP) and unshielded (UTP) twisted pair. With a cable that has at least one shield (STP, ScTP, FTP, PiMF), connectors are used to provide shield connection and (not always) shielding. The impedance of the cable used must match the impedance of the equipment it is connecting, otherwise interference from the reflected signal may cause the connections to fail. This is especially critical for high frequencies (100 MHz and above).

The most widespread are cables with a number of pairs of 2 and 4. There are also double designs - two cables of two or four pairs are enclosed in adjacent insulating stockings. The common stocking can also include STP+UTP cables. Of the multi-pair, 25-pair are popular, as well as assemblies of 6 pieces of 4-pair. Cables with a large number of pairs (50, 100) are used only in telephony, since the manufacture of multi-pair cables of high categories is a very difficult task. Each cable pair has its own twist pitch, which is different from the neighboring ones. This ensures a reduction in the mutual inductance and capacitance of the pair wires, and, consequently, a reduction in crosstalk. Since the wave characteristics of a pair (velocity, impedance, attenuation) depend on the twist pitch, the pairs in a cable are not identical. Each pair in a cable segment has its own “electrical length”, determined through the signal propagation time and the nominal (for a given cable) wave propagation speed. The "electrical length" of the pair will be different from the "mechanical" measured with a tape measure. Sometimes a variable twist pitch is used for each pair - this equalizes the average parameters of the pairs while maintaining an acceptable level of crosstalk.

According to the caliber - the cross section of the conductors - the cables are marked in accordance with the AWG standard (American Wire Gauge - American wire gauges). The main conductors used are 26 AWG (section 0.13 mm2, linear resistance 137 Ohm / km), 24 AWG (0.2-0.28 mm2, 60-88 Ohm / km) and 22 AWG (0.33-0, 44 mm2, 39-52 Ohm/km). However, the gauge of the conductor does not provide information about the thickness of the wire in the insulation, which is very important when terminating the ends of the cable into modular plugs, and the outer diameter of the cable, which can be used to calculate the cross section of the required cable channels.

Conductors can be rigid single-core (solid) or flexible stranded (stranded or flex), usually consisting of 7 wires (7-strand). Single core cable has better and more stable performance. It is used mainly for stationary wiring (it is also cheaper than stranded), which makes up the largest part in cable lines. A multi-core flexible cable is used to connect equipment (subscriber and telecommunication) with fixed wiring and patch cords.

Connecting equipment

Connecting equipment provides the ability to connect to cables, that is, provides cable interfaces. For twisted pair, there is a wide range of connectors designed for both permanent and detachable connection of wires, cables and cords. Of the one-piece connectors, connectors of types S110, S66 and Krone, which are industry standards, are common. Among plug-in connectors, the most popular are standardized modular connectors (RJ-11, RJ-45, etc.). For termination, the insulation from the wires is not removed - it is displaced during the termination of the connector contacts by the knives themselves. The procedure for terminating (terminating) wires into connectors of types S110, S66, Krone and the like using special percussion instruments is also called punching (punch down), and blocks with these connectors are called PDS (Punch Down System).

Connecting equipment also includes various adapters that allow you to join different types of cable interfaces.

Modular Jack (sockets, sockets) and Modular Plug (plugs) are the most commonly used connectors for 1-, 2-, 3-, 4-pair category 3-6 cables. Cable systems use 8- and 6-position connectors, better known as RJ-45 and RJ-11, respectively.

The designation RJ (Registered Jack - registered jack) actually refers to a connector with a specific wire layout and comes from telephony. Each of the jacks shown in the figure can be used with different RJ numbers.

RJ-45 modular plug

When installing a structured data cabling system, use 8-way connectors with an EIA/TIA-568A layout, abbreviated T568A, or EIA/TIA-568B, abbreviated T568B.

The disadvantage of all layouts is that at least one pair is not cut into adjacent contacts, but another pair is wedged inside it. This leads to an increase in crosstalk and signal reflection from the inhomogeneity that occurs when the wires of these pairs are more untwisted. For this reason, the use of conventional modular connectors for categories above 6th is problematic. The most common modular connectors are category 5 or 3, category 5 and higher connectors are also available for shielded wiring.

Category 5 and higher modular sockets always have the appropriate designation; they differ markedly from category 3 sockets in their design and the method of connecting wires. Here, the socket itself is mounted on a printed circuit board, on which blade contacts (such as S110, Krone or other design) are also installed to terminate the cable wires. The circuits are routed with printed conductors so that the wires of each pair are connected to adjacent contacts of the connector. In addition, the board has reactive elements that match the impedance, made by printing. Without these elements, on high-speed technologies (100 Mbps and above), problems associated with the reflection of signals from the connectors are possible.

modular socket

According to the design and method of mounting sockets, there are many options that can be divided into fixed configurations and typesetting (modular) systems. Fixed configuration sockets - wall-mounted for 1 or 2 of the same type sockets and blocks of 4, 6 or 8 sockets for patch panels - are usually attached to the printed circuit board on which they are mounted. To protect against dust, sockets with hinged covers or retractable spring-loaded shutters are used. For patch panels, the socket is best placed in the front position (plug enters from the front). For workplace outlets, the outlet can look both down and sideways (up is undesirable due to dust accumulation). In many cases, corner sockets are convenient. There are many mounting options, and with the outward similarity of sockets from different manufacturers, they often do not fit “non-native” fittings, it would seem, with the same dimensions.

The termination of wires into sockets is carried out with a tool corresponding to the type of connector (S110, Krone), or with the help of protective caps. There are designs of sockets assembled without tools - the wires are laid out in a plastic cover, and when it is put on, they go into the contact knives.

Modular Plugs different categories outwardly may not differ from each other, but have a different design. Category 5 plugs may have a separator that is slipped over the wires prior to assembly and crimping of the connector, which reduces the length of the untwisted part of the cable and facilitates the laying of wires. Contacts during installation (crimping) cut into the wires through the insulation. Plugs for solid and stranded cables differ in the shape of the contacts. Needle contacts are used for multi-core cable, the needles are stuck between the conductors of the wires, providing a reliable connection. For a single-core cable, contacts are used that “hug” the core on both sides. During crimping, the protrusion that fixes the cable is also pressed in (the part that is still in the stocking). The latch is used to snap the plug into the socket.

Using twisted pairwise insulated conductors. This type of cable is used in the field of telecommunications and is an integral component of structured cabling systems ().

As it has already become clear, the cable got its name from the use of twisted conductors in it in pairs, hence the twisted pair. What does it give in a technical question? The stranding is done specifically to reduce the impact of electromagnetic interference from external sources on the strands of the pair. And in category 5+ cables, the cores of each pair are twisted with different pitches to reduce interference from twisted pairs to each other.

Cable shielding is also used to protect against interference. And, in accordance with this, they are divided into two main types - shielded and unshielded. To understand what degree of shielding a cable has, it is necessary to understand its marking.

Cable marking

When choosing a cable, you will definitely come across its special marking. One of the parts in this marking carries information about the shielding of the cable. For example: “FTP cable cat. 5e CCA ”- let's figure out what the letters FTP mean in the name of this cable.

When marking cables, the following designations are used:

• TP (Twisted Pair)– type of twisting, twisted pair.
• U (unshielded)- the protective screen is missing.
• F (Foiled)- Foil is used as a screen.
• S (Shielded)- A wire braid is used as a shield.

According to the standard ISO/IEC 11801 for marking cables, a combination of these designations written in a certain order XX / YZZ is used. Where “XX” designates the overall cable shield, “Y” designates the shield of each pair, and “ZZ” designates the type of stranding.

But in practice, confusion arises due to the fact that manufacturers often mark cables with only three letters. What is twisted pair with UTP or FFTP marking, let's take a closer look.

The most common cables UTP(no shielding) and cables FTP(all pairs are enclosed in a common foil screen).

Twisted Pair Categories

There are currently seven categories of twisted pair cable in use. Their main difference is the cable bandwidth, which is a determining factor in the speed of information transfer and the ability to use special network technologies.

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There are several categories of twisted pair cable, which are numbered from CAT1 to CAT7 and determine the effective frequency range to pass. Higher category cable usually contains more pairs of wires and each pair has more turns per unit length. Unshielded twisted pair categories are described in the EIA/TIA 568 (American Commercial Building Wiring Standard) and in the international ISO 11801 standard.

Twisted pair category 1

CAT1 (frequency band 0.1 MHz) - a telephone cable, only one pair (in Russia a cable is used and no twists at all - “noodles” - it has no worse characteristics, but more interference). In the USA it was used earlier, only in a "twisted" form. Used only for voice or data transmission using a modem.

Twisted pair category 2

CAT2 (frequency band 1 MHz) - an old type of cable, 2 pairs of conductors, supported data transfer at speeds up to 4 Mbps, used in Token ring and Arcnet networks. Now sometimes found in telephone networks.

Twisted pair category 2

Twisted pair category 3

CAT3 (frequency band 16 MHz) - 4-pair cable, used in the construction of telephone and local networks 10BASE-T and token ring, supports data transfer rates up to 10 Mbps or 100 Mbps using 100BASE-T4 technology at a distance no further 100 meters. Unlike the previous two, it meets the requirements of the IEEE 802.3 standard.

Twisted pair category 3

Twisted pair 4 and 5 category

CAT4 (frequency band 20 MHz) - the cable consists of 4 twisted pairs, used in token ring, 10BASE-T, 100BASE-T4 networks, the data transfer rate does not exceed 16 Mbps per pair, is not used now.

CAT5 (frequency band 100 MHz) - 4-pair cable, used in building 100BASE-TX local networks and for laying telephone lines, supports data transfer rates up to 100 Mbps when using 2 pairs.

Twisted pair category 5

Category 5e twisted pair

CAT5e (125 MHz bandwidth) - 4-pair cable, enhanced category 5. Data rates up to 100 Mbps when using 2 pairs and up to 1000 Mbps when using 4 pairs. Category 5e cable is the most common and is used to build computer networks.

Category 5e twisted pair

Category 6 twisted pair

CAT6 (frequency band 250 MHz) - used in Fast Ethernet and Gigabit Ethernet networks, consists of 4 pairs of conductors and is capable of transmitting data at speeds up to 1000 Mbps. Added to the standard in June 2002.

CAT6a (500 MHz bandwidth) - used in Ethernet networks, consists of 4 pairs of conductors and is capable of transmitting data at speeds up to 10 Gb / s and is planned to be used for applications operating at speeds up to 40 Gb / s. Added to the standard in February 2008.

Category 6 twisted pair

Twisted pair category 7

A special place is occupied by category 7 cables (not UTP!):

CAT7 - the specification for this type of cable is approved only by the international standard ISO 11801, data transfer rate up to 10 Gbps, signal transmission frequency up to 600-700 MHz. This category of cable has an overall shield and shields around each pair. The seventh category, strictly speaking, is not UTP, but S/FTP (Screened Fully Shielded Twisted Pair).

Twisted pair category 7

Each individual twisted pair, which is part of the cable intended for data transmission, must have a characteristic impedance of 100 ± 25 Ohm, otherwise the shape of the electrical signal will be distorted and data transmission will become impossible. The cause of data transmission problems can be not only poor quality cable, but also the presence of "twists" in the cable and the use of sockets of a lower category than the cable.

The name "twisted pair" refers to a special type of cable product, which is a few twisted together insulated conductors. From above, such an education is covered with a protective shell that protects it from external influences. A general view of a classic twisted pair is shown in the figure below.

The combination of several wires in such a non-standard way is carried out in order to increase the mutual connection between the individual cores, as a result of which the influence of interference in the form of external e / m fields is noticeably reduced. In order to achieve even greater security of cable products, several pairs of conductors (up to 5 or more) can be combined into twisted structures. For a clear understanding of what twisted pairs are, let's first get acquainted with the main purpose and existing varieties of these electrical products.

Twisted pair is an integral part of branched cable systems of structured type. The latter are traditionally used for laying lines in computer and telecommunication networks, such as, in particular, Ethernet and USB. The relative cheapness and ease of installation of twisted lines is the main reason for their wide distribution in the construction of local cable networks (for the Internet, in particular).

General classification and purpose

The twisted-pair network cable is connected to the devices themselves via 8P8C connectors (they are often called RJ45). Depending on the composition of the special protective sheath, twisted pairs are divided into different types, namely:

• Products with coatings that protect wires from climatic influences (humidity, solar radiation, etc.);
• Cable products with sheath resistant to any mechanical damage;

Note! All these types of products do not have a special outer braid and fall under the category of "unshielded twisted pair".

• Cables from several pairs with an additional outer coating, designed in the form of a protective braid and excluding the influence of E/M pickups.

In products of the first two categories, sheaths of cross-linked polyethylene or other materials resistant to ultraviolet radiation and deformations are traditionally used. In this version, they can be laid outdoors, under the influence of the most unfavorable factors.

The shielded twisted-pair cable has an aluminum foil coating, covered with a copper braid on top, which makes it possible to protect information transmission channels from external electromagnetic interference.

According to the number of cores in each of the conductors, twisted pairs can have a single-core and multi-core version, the choice of which is determined by the operating conditions of the cable.

Products with one core are extremely rarely used for direct connection of equipment nodes, which is explained by their rigidity and the possibility of damage in places of kinks. On the other hand, this type of conductor is optimally suited for terminal sockets, the connection to which is made using the "wedge" method.

Despite their flexibility, multi-core types of twisted pairs have one significant drawback, which is manifested in the large attenuation of the signal passing through them. In this regard, they are widely in demand in the manufacture of special connectors (patch cords) installed at the junction of network devices with sockets.

twisted pair device

These products consist of one or several pairs of insulated copper wires, which are tightly twisted together. A common cable twist is made from pairs of conductors twisted along the central axis, protected by a common insulating sheath.

Additional Information. Sometimes a metal braid, polyethylene or more wear-resistant Teflon is used as a protective coating in a multi-core cable.

Due to the additional twisting of pairs of conductors around the central axis, it is possible to increase the degree of their protection from the effects of electromagnetic fields. In addition, this approach enhances the connection between individual cores, through which it is possible to send elements of a differentiated signal.

In order to improve the quality of pulses transmitted over a multi-core cable, as well as to reduce the level of mutual interference, the number of turns in adjacent cores is made different.

Twisted pair classification with protective sheath

Having become acquainted with what it is - twisted pair, you can proceed to a more detailed study of it. Consider a variation of this product, in which a special protective screen is used as a coating. In accordance with the design of such a screen, all known product samples can be divided into the following groups:

• Multi-core twisted pair with one common sheath made on the basis of foil;
• Shielded cable product having a common screen made in the form of a metal braid;
• The same multi-core cable, but in addition to the foil sheath, it has a braided screen;
• Cable, in which each twist has its own individual foil-based protective sheath;
• The same design, but supplemented by a common metal braid.

At the end of this list are products with a shielded metal braid made of not only each of the individual twists, but also a common bundle woven on their basis. The simplest and cheapest option for manufacturing a cable assumes that it does not have any protective sheath.

Categories of twisted pairs

The category of a twisted pair is understood as its characteristic, which determines the throughput of a given set of wires twisted into a bundle. With an increase in this indicator, the twisted pair category increases accordingly.

There are up to seven gradations of this parameter for various types of products. Taking into account the fact that subcategories are established for some of them, there are ten of them in total.

For a more complete and clear understanding of the differences between twisted pairs, a special marking has been developed that informs about the main parameters of this type of cable products. To distinguish on the basis of screening, for example, the marking elements used mean:

• U - complete absence of a screen;
• F - the presence of a screen made of foil;
• S - there is a screen in the form of a metal braid.

So, the designation UTP, for example, can be decoded as: unshielded twisted pair without protection, and S / FTP (SF / UTP) is a cable with a foil screen, additionally protected by a copper braid.

According to the color of the outer vinyl shell, all these products are divided into the following types:

• With a black vinyl coating used when laying outdoors (sometimes such a cable is additionally protected by a polyethylene film that increases its resistance to corrosion);

Important! This suspended cable is laid on a stretched steel cable.

• Twisted pair of gray color is intended for laying indoors;
• Products in orange insulation and marked "LSZH" are non-combustible, designed for installation in fire hazardous conditions.

In addition, twisted pairs can be round (universal) and flat in shape. The last type of wiring is laid under a decorative coating or wallpaper.

Marking features

There is no single rule applied when marking twisted pairs - each individual manufacturer highlights those parameters that seem to him the most significant in terms of conveying information to the user. In the first place, a sign indicating the manufacturer's code and cable brand is usually placed. For the indicator corresponding to the limiting temperature at which its operation is permissible, a separate icon is used, which is in the second position.

These designations are followed by the type of shielding, the number of pairs present in the cable, as well as the diameter of the core, marking for the connector, product category, its length and year of manufacture. Most of these notations have been discussed earlier, so we will focus only on new elements.

Conductor material and cross section

In the manufacture of twisted pairs, such common materials can be used as:

• Pure technical copper;
• Special steel with a thin surface layer of copper, marked CCS;
• Aluminum coated with a thin copper layer, marking which use the designation CCA.

Note! The use of a copper layer is typical for wires up to the fifth category inclusive; for the manufacture of twisted products of higher categories, pure technical copper (CM) is always used.

Considering this parameter is especially important when choosing a cable suitable for these specific operating conditions. If you want to provide a quality connection, of course, it is preferable to focus on pure copper. However, you should always remember how much such a product will cost (the price of copper on the market is quite high).

In cases where you have to work with such important objects as local networks, it is not recommended to save on the quality of twisted pairs. Otherwise, it may happen that for excessive legibility in choosing the price of a product, you will have to “pay off” with the continuous repair of already laid cable networks.

As for the section of individual conductors, they are marked according to the generally accepted AWG standard. With this method of product differentiation, the most popular conductors are 22, 24 and 26 AWG.

connector marking

The traditional marking for the connector under the name "RJ-45" ​​is more correctly represented as 8P8C, where there is an indication of the number of connector positions included in it. The designation 8P (Position) just indicates that eight cores are required to connect the cable.

While 8C is a sign that all eight contacts (Contact) will be used when joining.

In the initial period of operation, the RJ-45 connector was designated as 8P2C, since it used only two contacts, which is quite enough for organizing modem and telephone communications. With the development of communication technologies, the old designation lost its relevance over time, after which its new form became generally accepted, taking into account all 8 contacts.

In a specific example, suitable for most popular twisted products, the following designations can be represented.

On the presented twisted pair cable, the following code designations are clearly distinguishable:

• UTP - means that this cable does not have a shield;
• 4PR is an indicator of the presence of 4 pairs of conductors in it;
• 24 AWG - indicates the cross-sectional diameter of one core (sometimes it is indicated in millimeters).

In the final part of the review, we note that after getting acquainted with all the intricacies and features of a twisted pair device, if necessary, you can independently deal with its laying. At the same time, one should not forget that the choice of one or another type of cable product is determined by its purpose and method of laying.

Video

This won't halt the execution of your script, but as long as setTimeout() is an asynchronous function, this code

Console.log("HELLO"); setTimeout(function()( console. log("THIS IS"); ), 2000); console log("ME"); will print this in the console:
HELLO ME THIS IS *(note that ME is printed before THIS IS)
function sleep(ms) ( ms += new Date().getTime(); while (new Date()< ms) { } } now, if you want to sleep for 3 seconds, just use:
sleep(3000); example: http://jsfiddle.net/forgery/8t0neran/

Please note that this code will keep your script busy for n milliseconds. This will not only stop execution of Javascript on your page, but depending on the browser implementation, may possibly make the page completely unresponsive, and possibly make the entire browser unresponsive . In other words, this is almost always the wrong thing to do.
If you do sleep more than 10 seconds, browser shows alert: "A script on this page may be busy, or it may have stopped responding. You can stop the script now, open the script in the debugger, or let the script continue."

Friday, 15 May 2015

Wednesday, 17 December 2014

This is the second time I've come across this store and the utter stupidity of the staff, and the second time I say to myself: "Enough!". I really hope this time will be the last.

Decided to buy a gift for my wife for the holidays. Assuming possible problems, based on previous negative experience, I began to negotiate in advance. So...

Day 1 (Tuesday, November 25)

I went to the store's website, chose the phone I was interested in and pressed the "Buy in 1 click" button, entered my phone number and waited for a call back.

An hour passed, then another, and no one called me ...

Then I dialed their number from my mobile. The phone was picked up by the operator, who asked for information about me, specified what I wanted to buy and recommended additional accessories, with which I agreed. We agreed that I would apply for a loan through a bank, namely Alfa-Bank JSC. The request to the bank should have been transferred after they asked me for a bunch of more information. I clarified that I need the order not just like that, but by a specific date, and since it is issued as a loan, I ask you to bring it early, without waiting for approval from the bank, or reduce this period to a minimum.

Day 2 (Wednesday, November 26)

The next day, when I did not wait to receive a message about the order made - neither an SMS to the specified number, nor a letter to the specified mailbox, I had to call back again.

Naturally, it turned out that the bad person who placed my order yesterday either didn’t save it, or something else, but they didn’t find it. No, the operator, of course, said that everything was OK, but I just needed to clarify my data and for the second time arranged for me to poll all my data. At the end, she promised that everything would be fine.

Within half an hour I received an SMS notification that my order was placed.

Day 3 (Thursday, November 27)

The next day, not allowing the situation to take its course, I called the operator back to clarify when a representative of Alfa-Bank would contact me. It turned out that the operator did not know what and when it would be and gave me the phone number of the bank where I should call to find out this information.

Naturally, it turned out that this is just some number, and not a number where they can provide this information (well, at least the right bank). However, they still helped by giving the number of the credit department of their bank. When I called back, I found out that the data on my request had not been received.

I had to call back the Allo store operator, due to whose confusion, as well as some questions asked again, I realized that they simply did not send the application to the bank. Then followed the next assurances that everything will be fine.

Day 4 (Friday, November 28)

During the day, I called the bank and the store several times to find out about the status of my loan application. It's done! On the evening of the 4th day, my loan application was delivered to the bank. And then real Hell began, they asked me so much information - that I didn’t even know that there could be so much of it ... about me, relatives, work and my friends (well, at least they didn’t ask about my friends).

But they can come to me and apply for a loan only next week after this application is transferred to the responsible person in the bank.

So I did not manage to arrange everything I needed in one week.

Day 7 (Monday, December 1st)

From the very morning I began to call the bank to somehow force a loan. But it turned out that this responsible person should call me back as soon as he gets to the application, as he has some more questions.

At lunchtime, a bank employee called me back, clarified all the information again and told me about the terms of the loan. It turned out that I would have to pay a one-time loan insurance in the amount of 1% of the issued loan, while the accrual of interest on the loan would be 2% and would be accrued from the second month. For my case, it was ideal, since I needed a loan for a week (only to borrow the goods until the money arrived in my account). This worker said that he would send it to the credit commission for consideration.

Maximum, consideration by the credit commission is carried out in 8 hours, at the end of the consideration, the commission either approves the issuance of a loan, or refuses, but in any case, one more day burned out.

Day 8 (Tuesday, December 2)

In the morning, at 10 o’clock, they called me and said that the loan commission had approved my candidacy and the bank was ready to give me a loan, the courier was ready to bring all the necessary documents only tomorrow, since he already had everything scheduled for today. I once again reminded that I would need to do it as quickly as possible, since the store will not deliver the goods until they receive confirmation from the bank, which they will not be able to give until I sign the contract. Thus, after signing the contract tomorrow, they will be able to give an answer to the store and, at best, the store will send a request to move goods from another city only then, plus at least a day to move, and it will be good if I can get it this week, although all this mess brewed at the beginning of the last. To which in response I received a firm "NO", that it is impossible to speed up all this in any way.

After I agreed with all this, I was once again read out the list of my goods and the amount of payments from my side. BUT, the amount has already changed. It turned out that now I do not have to pay 1% as insurance compensation for loans, but about 8%. In response to my indignation, I was informed that I misunderstood the last time (unfortunately I did not think of recording a phone call earlier).

Naturally, such an overpayment did not suit me at all, so I refused the services of the bank, and since the deadline for the appearance of money in my account had already approached for all the time of this red tape, I decided to call the store and change the payment from a loan to cash. Which I did as quickly as possible. I tried to express my indignation at the impudence of the bank, but they were not accepted, saying that they could not influence the bank in any way - there is what it is.

I asked for the transfer to be done as soon as possible, since I am already ready to pay cash, and as soon as the goods are moved, I will take it. Surprisingly, it turned out that all the goods (here we quickly checked the list) have already been moved to Kyiv and are waiting for me. I asked to be moved to a store on Petrovka.

After that, as always, I was assured that everything was OK, and with that we said goodbye.

Day 9 (Wednesday, December 3)

Not expecting a dirty trick, I made the first call in the late afternoon to clarify whether my goods had been delivered to the store I specified. This is where the PROBLEMS began, yes, just like that in capital letters.

At first, they didn’t find me at all, after which they said that yes, my order was there, but it was issued on credit, and therefore there was no delivery to the store.

After that, I once again asked to change the type of payment, to which they said that everything was OK and they would contact me as soon as the goods were delivered to the store.

In the evening, he told his wife that she could call in tomorrow to pick up the goods in the store, only it would be necessary to agree on the time.

Day 10 (Thursday, December 4)

The problems started from the very beginning, when the wife called the store back in the afternoon, it turned out that there was no product there.

My wife called me, and I called the store again, it turned out that again they didn’t change the type of payment, but after not very long conversations and a lot of indignation on my part, I found out a strange situation: they do not have the opportunity to change the type of payment themselves, but only create application for a change, this application should be processed by one of the managers and appointed a responsible person who will call me back, again clarify whether it is that I want to change the type of payment and then make the change. At first, finding out this state of affairs puzzled me ... and only a little ahead of time, realizing this, I began to find out if they would call me back, and how long all this could go on.

They assured me that this time they would call back for sure, I agreed, but warned that I would call them every hour if they did not call back.

Called back within half an hour. BUT, it turned out that such a product is no longer available, so my application was closed altogether. No objections were accepted.

I called the store back to the support service again trying to restore justice, but it turned out to be beyond my power. The promotion ended, the goods ended, the reservation of the goods for me was only for payment on a loan, and I didn’t find out where the goods had gone, which had just been before the change in the form of payment.

Outcome

I learned how to file a complaint, filed it and that was it. So until now, no one has contacted me from the store and explained where the goods disappeared, which was registered under me and even delivered to the store.

After that, I went to another store, bought the goods and no problems.

If you want problems, use the services of the Allo store!