Probably, every user of a personal computer or laptop has faced issues of connecting a monitor or TV to it, as well as the state of the quality of the resulting image. And if earlier it was rather problematic to get a high-quality picture on the screen, today this problem does not exist at all. Of course, if your device has a DVI connector. We will talk about it, and also consider other existing interfaces for displaying an image on the screen.

Types of connectors for displaying images on a computer monitor or screen

Until recently, all personal computers had an exclusively analog connection to the monitor. To transfer the image to it, a VGA (Video Graphics Adapter) interface with a D-Sub 15 connector was used. Experienced users still remember the blue plug and 15-pin socket. But, besides it, video cards had other connectors designed to display images on a TV screen or other video device:

• RCA (Radio Corporation of America) - our "tulip". An analog connector designed to connect a video card to a TV, video player or VCR using a coaxial cable. It has the worst transmission characteristics and low resolution.
• S-Video (S-VHS) - a type of analog connector for transmitting a video signal to a TV, VCR or projector with the division of data into three channels responsible for a separate base color. The signal transmission quality is slightly better than the "tulip".
• Component connector - an output to three separate "tulips" used to display an image on a projector.

All of these connectors were widely used until the late 1990s. Of course, there was no question of any quality, since both TVs and monitors at that time had a very low resolution. Now we cannot even imagine how it was possible to play computer games while looking at the TV screen with a cathode ray tube.

With the advent of the new century, thanks to the introduction of digital technologies in the development of video devices, RCA, S-VHS and component output became less common. The VGA interface lasted a little longer.

A bit of history

The principle of operation of a conventional video card was that the digital image at the output from it had to be converted into an analog signal by means of a RAMDAC device - a digital-to-analog converter. Naturally, such conversion already at the initial stage worsened the image quality.

With the advent of digital screens, it became necessary to convert the analog signal at the output. Now monitors have also been equipped with a special converter, which, again, could not but affect the image quality.

And here, in 1999, seemingly out of nowhere appeared DVI - the latest digital video interface, thanks to which we can now enjoy the perfect picture on the screen.

The development of this interface device involved a whole group of companies, which included Silicon Image, Digital Display Working Group and even Intel. The developers came to the conclusion that there is no need to convert a digital signal to an analog one, and then vice versa. It is enough to create a single interface, and the image in its original form will be displayed on the screen. And without the slightest loss of quality.

What is DVI

DVI stands for Digital Visual Interface (Digital Visual Interface). The essence of his work lies in the fact that a special TMDS encoding protocol, also developed by Silicon Image, is used to transfer data. The signal transmission method through the digital video interface is based on the serial sending of information previously implemented by the protocol, with constant backward compatibility with the analog VGA channel.

The DVI specification provides for a single TMDS connection at up to 165 MHz and 1.65 Gbps. This makes it possible to obtain an output image with a resolution of 1920x1080 with a maximum frequency of 60 Hz. But here it is possible to simultaneously use a second TMDS connection with the same frequency, which allows you to achieve throughput of 2Gb / s.

With such indicators, DVI left other developments in this direction far behind and began to be used on all digital devices without exception.

DVI for normal user

If you do not delve into the wilds of electronics, then a digital video interface is just a special encoding device that has a corresponding connector on the video card. But how to understand that a computer or laptop has a digital output?

Everything is very simple. Video card connectors with a digital interface cannot be confused with others. They have a specific look and shape that differ from other nests. In addition, the DVI connector is always white, which makes it stand out from the rest.

In order to connect a monitor, TV or projector to a video card, simply plug in the plug of the desired wire and fix it with special manually screwed bolts.

Resolution and scaling

However, neither digital coding nor special video card connectors completely solved the problem of computer compatibility with a monitor. There was a question about image scaling.

The fact is that all monitors, screens and TVs that already have a DVI connector are not capable of outputting a higher resolution than their design provides. Therefore, it often turned out that the video card produced a super-quality picture, and the monitor showed it to us only in a quality limited by its capabilities.

The developers caught on in time and began to equip all modern digital panels with special scaling devices.

Now, when we connect the DVI connector on the monitor to the corresponding output on the video card, the device instantly self-configures, choosing the optimal operating mode. We usually do not pay any attention to this process and do not try to control it.

Video cards and DVI support

The first NVIDIA GeForce2 GTS series graphics cards already had built-in TMDS transmitters. They are widely used today in Titanium cards, being integrated into rendering devices. The disadvantage of built-in transmitters is their low clock frequency, which does not allow high resolution to be achieved. In other words, TMDS do not use the maximum advertised bandwidth at 165 MHz. Therefore, we can say with confidence that NVIDIA at the initial stage failed to adequately implement the DVI standard in its video cards.

When video adapters began to be equipped with an external TMDS operating in parallel with the built-in one, the DVI interface was able to produce a resolution of 1920x1440, which exceeded all the expectations of the company's developers.

In the Titanium GeForce GTX series, there were no problems at all. They effortlessly provide an image with a resolution of 1600x1024.

ATI has taken a completely different path. All of its video cards with DVI outputs also work from integrated transmitters, but they come with special DVI-VGA adapters that connect 5 DVI analog pins to VGA.

Maxtor specialists decided not to bother at all and came up with their own way out of the situation. The G550 series graphics cards are the only ones with a dual DVI cable instead of two signal transmitters. This decision allowed the company to achieve a resolution of 1280x1024 pixels.

DVI connector: types

It is important to know that not all digital connectors are the same. They have different specifications and designs. In our everyday life, the most common types of DVI connectors are:

• DVI-I Single Link;
• DVI-I DualLink;
• DVI-D Single Link;
• DVI-D DualLink;
• DVI-A.

DVI-I SingleLink connector

This connector is the most popular and in demand. It is used in all modern video cards and digital monitors. The letter I in the name means "integrated". This DVI connector is special in its own way. The fact is that it has two combined transmission channels: digital and analog. In other words, this is a DVI + VGA connector. It has 24 digital pins and 5 analog pins.

Given that these channels are independent of each other and cannot be used simultaneously, the device independently chooses which one to work with.

By the way, the first such integrated interfaces had separate DVI and VGA connectors.

DVI-I DualLink Connector

DVI-I DualLink is also capable of transmitting an analog signal, but unlike SingleLink, it has two digital channels. Why is this needed? Firstly, to improve throughput, and secondly, it again comes down to resolution, which is directly proportional to image quality. This option allows you to expand it to 1920x1080.

DVI-D SingleLink connector

DVI-D SingleLink connectors do not have any analog channels. The letter D informs the user that this is a purely digital interface. It has one transmission channel and is also limited to a resolution of 1920x1080 pixels.

DVI-D Dual Link Connector

This connector has two data channels. Their simultaneous use makes it possible to obtain 2560x1600 pixels at a frequency of only 60 Hz. In addition, this solution allows some modern video cards, such as nVidia 3D Vision, to reproduce a three-dimensional image on a monitor screen with a resolution of 1920x1080 with a refresh rate of 120 Hz.

DVI-A connector

In some sources, the concept of DVI-A is sometimes found - a digital connector for transmitting an exclusively analog signal. In order not to mislead you, we immediately indicate that in fact such an interface does not exist. DVI-A is just a special plug in cables and special adapters for connecting analog video devices to the DVI-I connector.

Digital jack: pinout

All of the listed connectors differ from each other in the location and number of contacts:

• DVI-I SingleLink - has 18 pins for a digital channel and 5 for an analog one;
• DVI-I DualLink - 24 digital pins, 4 analog, 1 - ground;
• DVI-D SingleLink - 18 digital, 1 ground;
• DVI-D DualLink - 24 digital, 1 ground

The DVI-A connector also has its own unique pin arrangement. Its pinout consists of only 17 pins, including ground.

HDMI connector

A modern digital video interface has other types of connecting communications. So, for example, the HDMI DVI connector is in no way inferior in popularity to the listed models. On the contrary, due to its compactness and the ability to transmit audio along with digital video, it has become a must-have accessory for all new TVs and monitors.

The abbreviation HDMI stands for High Definition Multimedia Interface, which means "High Definition Multimedia Interface". It appeared for the first time in 2003 and since then has not lost its relevance at all. Every year there are new versions of it with improved resolution and bandwidth.

Today, for example, HDMI makes it possible to transmit video and audio signals without loss of quality over a cable up to 10 meters long. The throughput is up to 10.2 Gb / s. Just a few years ago, this figure did not exceed 5 Gb / s.

This standard is supported and developed by the world's leading companies producing radio electronics: Toshiba, Panasonic, Sony, Philips, etc. Almost all video devices manufactured by these manufacturers today have at least one HDMI connector.

DP connector

DP (DisplayPort) - the latest connector that replaced the HDMI multimedia interface. With high bandwidth, minimal loss of quality during data transmission and compactness, it was intended to completely replace the DVI standard. But it turned out that not everything is so simple. Most modern monitors do not have the appropriate connectors, and changing their production system in a short time is an impossible task. In addition, not all manufacturers are particularly striving for this, which is why most video equipment is not equipped with the DisplayPort standard.

mini connectors

Today, when more mobile devices are used instead of computers: laptops, tablets and smartphones, it is not very convenient to use conventional connectors. Therefore, manufacturers such as Apple, for example, began to replace them with smaller counterparts. First VGA became mini-VGA, then DVI became micro-DVI, and DisplayPort dwindled to mini-DisplayPort.

DVI adapters

But what if, for example, you need to connect a laptop to an analog monitor or another device that has a DVI connector to a digital panel with the HDMI, DisplayPort standard? This will help special adapters, which today can be purchased at any electronics store.

Consider their main types:

• VGA-DVI;
• DVI-VGA;
• DVI-HDMI;
• HDMI - DVI;
• HDMI - DisplayPort;
• Display Port - HDMI.

In addition to these basic adapters, there are varieties of them that provide connection to other interfaces, such as USB.

Of course, with such a connection, there is a loss of image quality, even between devices of the same type that support the DVI standard. The adapter connector, no matter how high-quality it is, cannot solve this problem.

How to connect a TV to a computer

Connecting a TV to a computer or laptop is not difficult, but you should determine which interface is equipped with both devices. Most modern television receivers have built-in connectors that support DVI. It can be both HDMI and DisplayPort. If a computer or laptop has the same connector as the TV, it is enough to use the cable that is usually supplied with the latter. If the wire was not included in the kit, you can freely buy it in the store.

The operating system of the computer will independently determine the connection of the second screen and offer one of the options for its use:

• as the main monitor;
• in clone mode (the image will be displayed on both screens);
• as an additional monitor to the main one.

But do not forget that with such a connection, the image resolution will remain the same as provided for by the screen design.

Does cable length affect signal quality?

Not only the signal quality, but also the data transfer speed depends on the length of the cable connecting the device and the screen. Taking into account the modern characteristics of connecting wires for various digital interfaces, their length should not exceed the established indicators:

• for VGA - no more than 3 m;
• for HDMI - no more than 5 m;
• for DVI - no more than 10 m;
• for DisplayPort - no more than 10 m.

If you need to connect a computer or laptop with a screen located at a distance exceeding the recommended one, you must use a special amplifier - repeater (signal repeater), which can also distribute the channel to several monitors.

What is VGA, is there a difference with D-Sub?

VGA (D-Sub) is one of the most popular connectors in the history of digital technology. This standard is used in electronic devices that appeared on the market thirty years ago and to this day. Although this connector can no longer be called progressive, it is still easy to find it in various monitors, video cards and other electronic devices.

D-Sub (D-subminiature) is an analog fifteen-pin connector. As a rule, it is used to connect a computer or laptop to a monitor.

VGA (Video Graphics Array) uses progressive video transmission. When there is a change in the brightness level, the voltage is reduced or increased at the same time. Moreover, the signal voltage can vary from 0.7 to 1 V. If we consider CRT monitors, which most often contain VGA connectors, then they change the intensity of the beam created by the electron gun. As a result of such actions, the brightness of the display changes.

As for the difference between VGA and D-Sub, it simply does not exist, because we are talking about the same DE15 connector. This is a 15-pin connector, where each channel is responsible for certain functions. It is worth noting that in its appearance, VGA really resembles the letter "D". Hence the name - D-Sub.

What can be connected through the VGA connector?

Today, VGA is no longer considered a common connector for technology. But over the years of its existence, a variety of devices have received such a standard. For example, this interface is present in certain models of LCD and plasma TVs. It was often installed in DVD players. But the VGA connector is especially common in monitors with cathode ray tubes. Almost all CRT monitors were equipped with just such an interface for connecting to signal sources. Even early LCDs have this standard, which has been gradually replaced by DVI and HDMI.

History of the VGA interface

The VGA connector was announced in 1987 by the world famous IBM. It was specially designed for high-quality video signal transmission to screens using cathode ray tubes. Therefore, all computers relevant at that time worked with monitors that were equipped with this interface. It should be noted that up to this point there were DE-9 connectors, which were often used to connect joysticks to game consoles and PCs. At the same time, VGA (DE-15) received not 9, but 15 contacts at once. This made it possible to enjoy the color image that was displayed on CRT monitors.

In the 90s of the last century, many manufacturers of equipment also began to apply this standard. TVs and DVD players with VGA on board began to be produced. D-Sub retained its popularity until the DVI digital standard became widespread. Moreover, the official presentation of DVI took place in 1999. But he began to gradually push out the morally and physically obsolete VGA interface from the market only in the 2000s, when digital technologies and related content turned out to be in demand and available among users. Moreover, in 2015, AMD, Intel and many other major corporations decided to completely abandon the use of the VGA standard in their new products.

Types of D-Sub output

The VGA interface has used 15 pins since its launch. A progressive signal with an unstable voltage amplitude is transmitted through them. At the same time, today it is known that there are two types of this connector, which almost do not differ from each other:

• Standard VGA. This interface is used in many video cards and monitors, as well as some DVD players and TVs.
• Mini VGA. This connector can be found in laptops, as well as certain portable devices. In terms of appearance, it looks more like a USB port. But in terms of its capabilities, it is no different from a standard connector.

Specifications, features and pinout of the VGA Connector

As already noted, VGA (D-Sub) was designed for easy analog signal transmission. It uses 15 contacts, each of which performs a specific function.

You need to understand that there is a connecting cable "Daddy" and plug-in connections "Mom".

Therefore, the protruding connections must be connected exactly to the internal VGA holes. As for the contacts themselves, they lined up in three horizontal stripes of 5 pieces. Thanks to this, it is possible to transmit an analog signal, "broken" into blue, red and green colors.

Maximum resolution VGA (d sub)

VGA technology is officially capable of transmitting a video signal at a resolution of 1280 by 1024 pixels, but no more. In reality, the resolution can reach 1920x1080 (Full HD) and in some cases even 2048x1536. Until a certain time, this was quite enough to enjoy a high-quality image. But the higher the resolution of the transmitted signal, the greater the chance of getting unexpected defects in the form of image blur and other things. Therefore, experts recommend using more advanced interfaces for FHD monitors.

Pros and cons of VGA interface

Key Benefits :

1. A huge number of devices released over 30 years.
2. Large selection of different adapters.
3. Ideal for CRT monitors and analog signal transmission.
4. The only analog interface that can transmit high-definition video.

Connector Disadvantages :

1. There is no possibility for simultaneous transmission of video and audio signals (only video is transmitted).
2. The officially declared maximum resolution is 1280 x 1024. There may be problems when displaying images on FHD displays.
3. If you use a low-quality cable, interference will occur.
4. Not very suitable for connecting digital devices.

Types of converters and converters for VGA

If you have, for example, an old video card with a VGA connector, but you decide to buy a new monitor with digital interfaces, then you can’t just connect them. In such cases, you need to additionally change the video signal source, or purchase a special converter. In the latter case, there is no need to buy expensive components. It is enough to find (buy) a VGA to HDMI or DVI signal converter so that the new monitor can delight you with a clear and colorful picture without having to change the video card.

Today in the free sale you can find a huge number of various adapters. With their help, you can convert the signal from VGA to DVI, Display Port, HDMI and so on. Many converters are equipped with a USB cable, through which it is possible to transfer not only video, but also sound. Backward compatibility is not excluded at all, when a signal from a digital standard is transmitted to a monitor with a VGA interface.

Relevance of VGA for today, what is better vga or hdmi?

In today's realities, when digital content dominates, there is no point in counting on the capabilities of D-Sub (VGA). It is enough to look at the various devices and components that have been produced by manufacturers recently. And we will find that among the interfaces there will be HDMI, Display Port or DVI. It is they who provide high-quality display of high-definition images (Full HD and 4K). On the other hand, VGA is still with us. Over the years, companies have released an incredible number of devices that support this standard. Therefore, it is still too early to completely reset it with an account. But hope for a miracle is hardly worth it. It should be understood that even with the use of adapters, it is impossible to achieve complete synchronization between analog and digital interfaces. Defects will certainly appear somewhere, or the image will not be “opened” to the fullest.

D sub(D-subminiature) is a line of electrical connectors popular in computer technology. When it appeared on the market, the “subminiature” connector fully justified its name. However, today, it can hardly be called such, rather, on the contrary - one of the most massive computer signal connectors.

Description

The D-sub interface includes two (or more) parallel rows of pins and sockets. As a rule, they are surrounded by a metal shield resembling the Latin letter D. It provides a mechanical connection between the connector and the plug, and also shields the interface from electromagnetic interference. This uniquely shaped connector is very convenient as it eliminates miswiring. The side of the connector that contains the contacts is called male connector ("dad"), the other containing nests - female connector ("mum"). The shield of the socket fits inside the shield of the plug. If shielded cables are used, then the connector shields are connected to the cable shields. Thus, continuous shielding of the entire connection is ensured.

D-sub connectors were developed by ITT Cannon, a division of ITT Corporation. The date of creation of the connector is the distant 1952. The company's internal naming convention indicates that the "D" character is the designation for the entire D-sub series of connectors; the second letter is used to designate the size of the connector, which depends on the number of standard pins located inside the D-shaped shield (A = 15, B = 25, C = 37, D = 50, E = 9); then the number of actually used contacts is located, and with it the letter that characterizes the "gender" of the connector: M - "father", F - "mother", P - plug / "father", S - socket / "mother". For example, DB25M should be decoded as follows: a D-sub connector with a screen, and the actual number of contacts is 25. The contacts in the connector are located at a distance of 2.77 mm, the rows at a distance of 2.84 mm.

Cannon also makes D-sub connectors with connections that have larger connectors than conventional pins. These connectors can be used for both high voltage and coaxial connections. They take the place of several standard contacts at once.

Name confusion

Due to the fact that DB-25 connectors were widely used for parallel and serial ports, most users, not understanding that "B" stands for screen size, began to refer to the D-sub connector itself in a different way: DB. Although, according to the rules, designations such as “DA”, “DC”, or “DE” should have been used. The same goes for the DB9 connector, which is what the regular 9-pin connectors started to be called when they should have been called DE9. This has led to the fact that DE9 connectors are often sold as DB9 on the market today. DB9 is often referred to as a 9-pin connector with an E screen size.

There are now special D-sub connectors that have a standard screen size but have more pins and the names still use the same nomenclature.

There are connectors with even higher contact density, they are called "double density" (double density): DE19, DA31, DB52, DC79 and DD100. All connectors have four rows of pins.

In addition, there is another family of connectors that are often confused with D-sub, although this family is not included in this standard. These connectors are referred to as, for example, HD50 and HD68. They also have a D-shaped connector, but this connector is almost twice as thin as the DB25. These connectors are typically used in SCSI connections.

Description of D-sub connectors is available in DIN 41652.

Application

D-sub connectors are very popular in the field of data transmission via the RS-232 serial interface, despite the fact that the standard does not oblige its use for this purpose. Initially, DB25 was used in RS-232, but due to the fact that many applications used only a part of the contacts, it became possible to introduce 9-pin DE9 connectors for this purpose.

In a PC, 9- and 25-pin connectors are used for:

• serial port (RS-232);
• parallel (IEEE 1284) printer port.

The IEEE 1284 standard uses a DB-25 connector on the PC side, it is called "IEEE 1284-A", and on the printer side, the connector is "IEEE 1284-B" (borrowed from Centronics).

The DE9 plug on the back of the IBM PC is typically an RS-232 connector. It was first used on PC in 1984. A 9-socket socket was also usually located there, acting as a video card output to a monochrome, CGA, or EGA monitor. Despite the fact that all interfaces used the same connector, only a certain type of monitor was used with the video card, since connecting a different type of monitor could result in a monitor burnout.

More modern video cards, the VGA standard, used the DE15 connector, it had 15 pins built in 3 rows. This connector is also known as HD15, where HD = High Density.

To date, the designation D-sub in the descriptions of video cards is used only for DE15 connectors.

By the end of the 70's, and throughout the 80's, DE9 connectors, not equipped with a screw connection, were used everywhere to connect control devices. The connector became the de facto standard after being used in the Atari 2600 video game console, as well as in Atari's line of 8-bit computers. In addition, these computer connectors are used by the following systems: Atari, Commodore, Amstrad, SEGA.

Many uninterruptible power supplies are equipped with a DE9F connector, which performs the functions of exchanging signals with a computer - in order, for example, to report on the battery charge level. Most of these devices do not use a standard serial port interface, but their own wiring, which varies from manufacturer to manufacturer. Some companies deliberately use non-standard wiring to compete: to force the user to use their proprietary cable.

In addition, the following connectors are also used in D-sub technology:

• 15-pin DA15 (two rows: 7 and 8 pins) - used to connect a color monitor in early Mac computers, as well as to connect to network cards;
• 37-pin DC37 (two rows: 18 and 19 pins);
• 50-pin DD50 (two rows of 17 and one row of 16 pins).

#VGA #DVI-D #DVI-I #HDMI #DisplayPort

Interfaces that are widely used at the present time:

VGA

(D-Sub)- the only analog monitor connection interface still in use today. Morally obsolete, but will be actively used for a long time. The main disadvantage is associated with the need to use double conversion of the signal to analog format and vice versa, which leads to a loss of quality when connecting digital display devices (LCD monitors, plasma panels, projectors). Compatible with video cards with DVI-I and similar connector.

DVI-D

- basic type of DVI interface. It implies only a digital connection, therefore it cannot be used with video cards that have only an analog output. Very widespread.

DVI-I

- an extended version of the DVI-D interface, the most common at the present time. Contains 2 types of signals - digital and analog. Video cards can be connected via both digital and analog connections, a video card with a VGA (D-Sub) output can be connected to it through a simple passive adapter or a special cable.
If the documentation for the monitor indicates that this modification uses the DVI Dual-Link option, then in order to fully support the maximum monitor resolutions (usually 1920 * 1200 and higher), the video card and the DVI cable used must also support Dual-Link as a full interface option DVD-D. If you use the cable that came with the monitor and a relatively modern (at the time of writing the FAQ) video card, then no additional purchases are required.

HDMI

- adaptation of DVI-D for consumer equipment, supplemented by a digital interface for transmitting multi-channel audio. It is present in virtually all modern LCD TVs, plasma panels and projectors. To connect a video card with a DVI-D or DVI-I interface to the HDMI connector, a simple passive adapter or cable with the appropriate connectors is enough. It is impossible to connect a video card with only a VGA (D-Sub) connector to HDMI!

Legacy and exotic interfaces:

31. 01.2019

Blog of Dmitry Vassiyarov.

D-sub connector and what can be connected to it

I am glad to welcome you, my friends.

I decided to expand the collection of my articles on contact interfaces used in computers and other technology. Those interested in this topic always ask the question: what is a D-sub connector? It really deserves your attention, because for a long time it was the most common, and even now it is successfully used in some devices.

The history of the name of this connector is very original. If the designations familiar to us, USB, HDMI are an abbreviation of the English definition, then in the case of D-sub, everything is different.

Its full name is “D-subminiature”, where D is a simplified designation for the shape of the connector itself, which from a geometric point of view is a trapezoid with rounded corners and, of course, resembles this letter. "Subminiature" - "very miniature." At one time, this, without false modesty, was the most accurate description of the dimensions of an innovative connector.

For the first time, experts saw the D-sub pin connector in 1952 in the products of the American company ITT Cannon, which is part of the international corporation IT-Ti. ITT Corporation has worked closely with the US Department of Defense. And its development was created with the prospect of being used in military equipment.

Ideal Connector Design

With the task of reducing the number of wires and connections, as well as minimizing the area occupied by the connectors, ITT Cannon specialists coped brilliantly, because their universal brainchild, the D-sub connector in different versions, has existed for more than half a century and is still in demand in some devices. Let's take a look at it:

• The base of the connector is a plastic insulator plate (polystyrene, sometimes reinforced with fiberglass). It serves as a mount and a separator for contacts.
• Along its perimeter is the same galvanized (or tinned) steel plate resembling the letter D. This is an important structural element that performs three functions at once:
• It is the basis for reliable fastening of the plug in the socket;
• Protects (shields) transmitted signals from possible electromagnetic interference;
• Its shape determines the mutual orientation of the corresponding contacts and makes it impossible to connect incorrectly;
• In the classic version, the contacts are thin pins (and, accordingly, tubes in the socket) made of nickel-plated bronze. The most critical connectors use gold plating. Contacts are located in two or three rows at an equal distance from each other with a normal or increased density. The number of contacts is strictly fixed and determined by the data transfer protocol and the power system. There are D-sub for 9, 15, 25, 37, 50 and more contacts.

• In some modifications of the connectors, thin pins can be supplemented with reinforced contacts for transmitting a coaxial signal or a powerful power supply. They are used, for example, to transmit high-quality images with RGB separation of the analog signal.

The housing is an equally important part of this connector.

• As such, it is present only at the plug and can be cast or collapsible (on screws or latches for quick assembly). It is made of durable plastic or metal (steel, aluminum). A feature of the D-sub plug housing is the presence of two fixing screws that attract it to the socket and prevent accidental disconnection of the contacts. Their twisting from the side of the fork can be done with a special tool or manually, due to the corrugated notches on the head of the screws.

Such a connector, like any other, is divided into two parts. On the plug (plug) there are pin contacts and an outer (covering) screen.

This part, connected to the external cable, is also called the "plug", "male" or "male connector".

The socket has an internal screen and contacts made in the form of tube sockets. This element is also called "mother", "socket" or "female connector". English versions of denoting wordings are used in labelling.

Fastening the cable to the contacts

One of the design features of the D-sub connector is the variety of ways to connect to the cable:

• Soldering, according to experienced professionals, is the most time-consuming, but also the most reliable method of installation. To facilitate this procedure, the back side of the contacts is made in the form of a semi-cylindrical or flat surface;

• Removable crimp contacts allow you to speed up the connection process. After performing this operation, they are placed back in their nests on the insulator;
• In the case of using a cable-loop, it is worth giving preference to connectors with a device for pinning contact surfaces;

• the fastest installation is D-sub with a self-clamping device. You will need to decompose the wires into contact cells and fix them with a special insert.

The mounting structures provide for cable outlets in different directions (straight or at an angle).

Learning to unravel unusual markings

Now that we have learned about the variety of D-sub connectors, I propose to talk about their markings. And here we are in for a mess. The fact is that ITT Cannon offered letter designations for different sizes corresponding to a certain number of contacts.

But their number is already indicated in the designation. Writing an extra letter is not entirely reasonable. Although many out of habit often indicate "B" (corresponding to 25 contacts). So you may well come across DB9S or DB50M. Ignore the "B" attention, but take a closer look at the last letter. Remember the previous discussion about plugs and sockets. So here it is in this case, respectively, "socket" and "male connector".

Even in the marking there is the letter “W” with a number indicating the presence of additional reinforced contacts, and the combination “HD” indicates a high density of plugs and sockets.

Continuing the conversation about the D-sub designations, it is worth noting that the companies involved in their production offer their own options for marking the way the wires are attached and the location of the cable. And yet, if you find “MIL” in the name of the connector, then this will indicate its high quality and reliability, corresponding to the standards of the US Department of Defense.

What is D-sub for?

The application parameters of the "Di-sub" connectors are cable lines with a current strength of up to 5 amperes, with an insulation resistance of 1000 MΩ and contacts of 30 MΩ. This is information for specialists, but we are interested in what D-sub is used for.

This connector was created based on telecommunications needs, and meant the use of the RS-232 protocol to connect a modem to a computer. This interface provided high reliability for serial signal transmission. For which he received the name of the serial port of the PC. Although he had a low throughput, he was unpretentious in operation and simply programmed for different purposes.

Due to this, almost all devices connected to computing and networking devices (before the USB era) used the D-sub connector.

Their list is quite large, but here are just a few well-known examples:

• game consoles and joysticks;
• network adapters and modems;
• printers;
• uninterruptible power supplies;
• mice.

Do you need examples? The older generation probably remembers such a computer as the ZX Spectrum? So he had an expansion port into which you could stick all sorts of cool things, such as a printer or a joystick.

But of course, the most common use of this connector to this day is to transmit a video signal to TV, projectors and monitors. Of course, it is being replaced by digital. But where there is only a DB15HD socket, you can still get a picture with HD resolution.

Having touched on the topic of connecting to different devices, it should be said that in some cases it is necessary to use adapters between D-sub with a different number of contacts. There are also adapter options between the DVI and VGA version of the "Di-sub".

So, friends, this legendary D-sub connector. Now you have learned a lot about him and probably imbued with respect for this fighting "old man". And I end my story and wish you all the very best. See you again on my blog.