Komunikačné moduly

Komunikačné moduly umožňujú dátovú komunikáciu v rozličných formátoch. Vo všeobecnosti, všetky komunikačné moduly dokážu prenášať rovnaké data, ale rozdiel je v spôsobe ako sa to vykonáva – protokol, hardvérové požiadavky a rozdiel je tiež v maximálnej rýchlosti prenosu dát.

 

Wired and wireless communications enable widely used communication and data transfer between various devices. They enable remote control and monitoring of production processes, tracking in logistics, data acquisition and archiving and many other everyday used functions. Wireless communications also enable for example remote control and monitoring in various hazardous environments, where direct human presence would be dangerous or impossible. Further, wireless communications enable to avoid necessity of costly cable structure, especially in places distant from each other.

Classification

 

Communication systems differ in many aspects like power consumption, max. distance, data transfer speed, immunity to noise and disturbances, safety and other. A choice of a right communication system and components for your application depends on above mentioned factors, as well as for example on development and production costs. Wireless communications in general offer a big advantage of avoiding a cable structure and provide a big flexibility and expansibility. However, it is also advisable to take in mind possibility of interference, caused for example by surrounded machines, as well as limited bandwidth. Wired communications in general offer higher transfer speeds and from some point of view, also a higher data safety.

Terms

Bluetooth

An open wireless technology standard for exchanging data over short distances (using short wavelength radio transmissions in the ISM band from 2400-2480 MHz) from fixed and mobile devices.

LAN

Local Area Network, is a computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building. LAN usually features high data-transfer rates. Network topology describes the layout pattern of interconnections between devices and network segments. Switched Ethernet has been for some time the most common Data Link Layer and Physical Layer implementation for local area networks. At the higher layers, the Internet Protocol (TCP/IP) has become the standard. Smaller LANs generally consist of one or more switches linked to each other, often at least one is connected to a router, cable modem, or ADSL modem for Internet access.

WiFi

A trademark of the Wi-Fi Alliance and the brand name for products using the IEEE 802.11 family of standards, allowing electronic devices to exchange data wirelessly over a computer network. Wi-Fi uses 2.4GHz band and allows cheaper deployment of local area networks (LANs).

RFID

Radio-Frequency Identification is the use of a wireless non-contact radio system to transfer data from a tag attached to an object, for the purposes of automatic identification and tracking. Most of tags require no battery and are powered by the radio waves generated by an RFID reader device. The tag contains an antenna (made of an inductor) and a chip with a stored information. Tag can be read from up to several meters away. RF ID tags are used in many industries, for example an RFID tag attached to a product can be used to track its progress through the assembly line.

ZigBee

ZigBee is a specification for a suite of high level communication protocols using small, low-power digital radios based on an IEEE 802 standard for personal area networks (PANs). ZigBee technology is intended to be simpler and less expensive than other WPANs, such as Bluetooth. ZigBee is targeted at radio-frequency (RF) applications that require a low data rate, long battery life, and secure networking. ZigBee has is best suited for periodic or intermittent data or a single signal transmission from a sensor or input device. ZigBee operates at frequencies 868 MHz and 2.4 GHz.

 USB

Universal Serial Bus (USB) is an industry standard developed in the mid-1990s that defines the cables, connectors and communications protocols used in a bus for connection, communication and power supply between computers and electronic devices. USB was designed to standardize the connection of computer peripherals, both to communicate and to supply electric power. USB has effectively replaced a variety of earlier interfaces, such as serial and parallel ports, as well as separate power chargers for portable devices.

RS485

also known as TIA/EIA-485, is a standard defining the electrical characteristics of drivers and receivers for use in balanced digital multipoint systems. Digital communications networks implementing the RS-485 standard can be used effectively over long distances and in electrically noisy environments. Multiple receivers may be connected to such a network in a linear, multi-drop configuration. These characteristics make such networks useful in industrial environments and similar applications.

434/868 MHz RF

is a license free frequency band, used by low power devices. 433 MHz communication modules are short range communication devices authorized for use in many parts of the world. They operate in the UHF band from 433.075 MHz to 434.775 MHz. Modules working on this frequency are very often used for remote control of doors and locks.

RS232

is the traditional name for a series of standards for serial binary single-ended data and control signals connecting. An RS-232 port was a standard feature of a personal computer, but the limited transmission speed, relatively large voltage swing, and large standard connectors motivated  development of the USB which has displaced RS-232 from most of its peripheral interface roles. Many modern personal computers have no RS-232 ports and must use an external converter to connect to older peripherals. RS232 devices are still found especially in industrial machines or scientific instruments. Because the voltage levels are higher than logic levels typically used by integrated circuits, special intervening driver circuits are required to translate logic levels.