Contact reader of keys. What are the electronic readers and where are they used. Major equipment manufacturers

An access control reader is a device for extracting a code from a carrier and then transmitting it to a controller. The carriers of the code are represented by contactless magnetic cards, key fobs, keys, bracelets, tags or biometric data.

Devices can be networked and standalone. The former scan and transmit the personal code to the central access control device, the latter are equipped with a built-in controller for processing incoming information. Depending on the type of interaction of the scanning surface with the identifier, readers have the following classification:

• Contact, reading the identification code from magnetic or Touch Memory keys during physical contact with the carrier;
• Contactless or Hands-Free readers, remotely recognizing a personal code from a microcircuit. Within this group, there are devices operating with proximity cards at a frequency of 125 kHz and devices operating at a frequency of 13.56 kHz;
• use for recognition the unique physiological parameters of a person;
• or combined devices that combine several detection methods at once. They are always equipped with a built-in controller for encoding conversion.

Non-contact devices also differ in reading radius and can be of short range - up to 10 centimeters of recognition, medium range - up to 1.5 meters, and high range - more than 1.5 meters.

Features and principle of operation of reading devices

Entrance access control systems consist of two mandatory elements - a reader and a controller, which can be either separate devices or integrated into a single housing. The identifier transmits a constant radio signal, which, when the carrier with a unique code is presented, transmits information to the controller.

The catalog of our store contains a line of reading devices manufactured by Parsec, IronLogic, PERCo, PROX, Smartec, Bolid. All of them differ in the method of detection, place of installation, peculiarities of operation and other parameters. Also our store provides and technical support security equipment.

The design of the contact reader is extremely simple - a metal case and a round contact pad, separated by an insulating pad.
The ground wire is soldered directly to the chassis and the TM wire is soldered to the round pad.
Instead of soldering, fastening under a screw or a nut is possible. A common malfunction is spontaneous unscrewing of the center contact retaining nut.
Some models of the reader have a LED for indication or backlighting.

The diagrams in the article "" indicate the voltage for which the indicator or backlight is designed. In most cases, the indicator is designed for 3 ... 5 volts. To "remake" the indicator to 12 volts, you need to include a 1 kOhm resistor in the break of one of the indication wires. This is exactly what is done in the 12 volt backlit models.

▼ Between contact pad and body connected the reader should be 4 ... 5 volts coming from the controller. Plus on the center contact.

▼ To check unconnected the reader needs to ring one wire with the contact pad, and the other with the case. There should be a resistance close to zero.

▼ We find out the polarity of the LED with a multimeter at the limit of 200Ω or 2000Ω. We apply the probes to the LED contacts. If the indicator is off, we swap the probes. If it is on, we look at which wire the red probe is attached to - this is a positive contact.

Touch Memory readers or contactless electronic card readers are key ACS devices. Contactless electronic card readers use different information transfer technologies: HID Proximity, Em-Marine or Mafare.

Regardless of the way they receive the signal, they can be divided into two types:

Brief classification of electronic readers

Depending on the way the identifier acts on the sensitive element, the following are distinguished:

Depending on the type of card, a distinction is made between:

• V budget systems access control, unique codes are recorded on the Proximity card, they can be transmitted by remote keyfobs and other devices that broadcast the identification code at a frequency of 125 kHz.
• More reliable devices use smart cards operating at 13.56 MHz.

Magnetic card readers differ in the power of the scanning elements that are triggered at different distances from the instrument panel:

• up to 10 cm - low-power;
• up to 1.5 m - medium power;
• more than 1.5 m - high-power.

IMPORTANT! Recently, universal smart card readers are often used to standardize access control. These scanners can perceive transmitted information (RFID technology) from identifiers of several formats. Such models necessarily have a built-in controller, on which universal communication protocols are stitched, converting the incoming code into a format perceived by the system. For example: the code received in a contactless way from the Mifare card can be converted into the Dallas Touch Memory standard.

Contact readers

The unique key comes from the magnetic strips of the card. One of the important operating factors is the correct positioning of the magnetic stripe on the card relative to the reader scanners.

Depending on the density and location of the magnetic field, a distinction is made between:

Depending on the model of the device, a distinction is made between:

• contact magnetic card readers with manual feed (both remote and built-in);
• automatic devices with a motorized transponder.

The latter devices are much more expensive, but they give significantly fewer errors, which significantly increases the service life of the card.

Due to the affordable cost of such devices, they have a wide range of applications:

• ACS,
• payment for public transport,
• banking operations (terminals, ATMs),
• accumulative and bonus cards of various loyalty programs.

Contactless readers

For one of the first contactless RFID identification data transmission technologies, two standards were developed and are still successfully used:

Proximity. This technology is used by Em-Marine, Indala and HID Prox standards. Exchange identification code for these standards it is carried out between the reader (studies a radio signal at a frequency of 125 kHz) and a transponder (forms a response message at a frequency of 62.5 kHz). The most popular proximity readers perceive a signal at a distance of 10-25 cm. However, some models can work with a card at a distance of up to 70 cm. public transport, such devices have a wider field of application. Most often, proximity technologies are used to identify goods, components, animals, etc.

Major equipment manufacturers

• Motorola, Texas Instruments, HID (US), Philips and EM-Marine (EU) manufacture microchips (off-the-shelf hardware) that exclusively support in-house standards.
• Impro, Microchip, Atmel manufactures systems and components for them, using existing developed standards.

 

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