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There are many categories of Ethernet cables we can use like CAT-4, CAT-5, CAT-5E, CAT-6, CAT-6A, etc. In our tutorial, we are going to use CAT-6E cable which has 4 twisted pairs of 24AWG wires and can support up to 600MHz. It is terminated at both ends by an RJ45 connector. In this tutorial, we are going to learn about the RS485 communication protocol and how to implement it with the two Arduino Nano we have with us and how to use the MAX485 RS485 to UART conversion Module. There are many different types of serial communication protocols like I2C and SPI which can be easily implemented with Arduino and today we are going to look at another most commonly used protocol called RS485 which is very commonly used in high noise industrial environments to transfer the data over a long distance. Shown below is the example of how a character is a transmitter over a UART data line.

2 Alphanumeric LCD, and MAX485 UART to RS485 converter IC connected to each end of an Ethernet Cat-6E cable via an RJ45 connector. The most common cable type is Cat 5e-UTP (unshielded twisted pair) which may work over shorter distances in less demanding applications with low EMI noise levels. Grounds between buildings may vary by a small voltage, but with very low impedance and hence the possibility of catastrophic currents - enough to melt signal cables, PCB traces, what is rs485 cable and transceiver devices. The data exchange format may be a line of ascii text. But there are some limitations to it as it cannot support multiple slaves and multiple masters and the maximum data frame is limited to 9 bits. The driver is limited for short-circuit current and the driver outputs can be placed at a high impedance state through the thermal shutdown circuit. The QVGA Controller’s kernel software contains a complete set of high level driver routines for the Serial2 port, and these functions are summarized in the Control-C Glossary. Consult the data sheets for any peripheral devices that you are interfacing to the SPI and, if a different configuration is needed, follow the instructions below to set up the appropriate SPI data transfer protocol.

5. Support coordinate display and angle acceptance instructions. It also has onboard LEDs to display the current state of the chip i.e. whether the chip is powered or its transmitting or receiving data making it easier to debug and use. 5V power supply and the rated current is 300 μA. It works on half-duplex communication to implement the function of converting the TTL level into RS-485 level which means it can either transmit or receive at any time, not both, it can achieve a maximum transmission rate of 2.5Mbps. MAX485 transceiver draws a supply current of between 120μA and 500μA under the unloaded or fully loaded conditions when the driver is disabled. EIA-485 (formerly RS-485 or RS485) is an OSI Model physical layer electrical specification of a two-wire, half-duplex, multipoint serial connection. Be sure to use a wire pair such as the blue and blue/white pair for the data lines and a third wire or pair twisted together for the common connection.

The connection diagram for the above circuit is also given below. The below image shows the transmitter and receiver circuit diagram for Arduino's long-distance wired communication. Most of the low-cost sensors and other modules like GPS, Bluetooth, RFID, ESP8266, etc. which are commonly used with Arduino, Raspberry Pi in the market uses UART TTL based communication because it only requires 2 wires TX(Transmitter) and RX (Receiver). UART is an Asynchronous transmission device hence there is no clock signal to sync the data between the two devices instead it uses start and stop bits at the start and end of each data packet respectively to mark the extremities of the data being transferred. Since it uses a differential line over twisted pair (like EIA-422), it can span relatively large distances (up to 4000 feet or just over 1200 metres). But if you are building a control system with these development boards over a distance greater than 10 to 15 meters, then you should take the noise and signal power into consideration because if you want your system to work reliably, then you cannot afford to lose the data while transferring. We have been using Microcontroller Development Boards like Arduino, Raspberry Pi, NodeMCU, ESP8266, MSP430, etc. for a long time now in our small projects where most of the times distance between the sensors and board is not more than few centimeters at max and at these distances, the communication between the different sensor modules, relays, actuators, and controllers can be easily done over simple jumper wires without us being worried about the signal distortion in the medium and the Electrical noises creeping into it.