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. 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. It is not a standard Communication protocol, but it is a physical circuit with which you can transmit and receive serial data with other peripherals. 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 main reason behind using these Ethernet Cables over normal wires is that they provide much better protection against noise creeping in and distortion of the signal over high distances. They have Shielding Jacket over the insulation layer to protect against the Electromagnetic Interference and also each pair of wires is twisted together to prevent any current loop formation and thus much better protection against the noise. This ensures maximum protection for the inner core. Typical line voltage levels from the line drivers are a minimum of ±1.5 V to a maximum of about ±6 V. Receiver input sensitivity is ±200 mV. The RS485 receiver compares the voltage difference between both lines, instead of the absolute voltage level on a signal line. Clueing in from its name, this is a USB to RS485 converter with industrial-grade features. 2 Alphanumeric LCD, and MAX485 UART to RS485 converter IC connected to each end of an Ethernet Cat-6E cable via an RJ45 connector.

We will send some data from the transmitter side over the cable from the Nano which is converted to RS485 signals via MAX RS485 Module working in Master Mode. We start with including the standard library for driving the LCD and declare the D8 pin of the Arduino Nano as an output pin which we will later use to declare the MAX485 Module as a transmitter or Receiver. 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. What is rs485 cable? You can easily connect more devices by splitting the cable at one connector and adding another cable to it. On the other hand, RS485 is more industry-based communication which is developed for a network of multiple devices that can be used over long distances and at greater speeds too. Twisted pair also allows the transmission speeds to be much higher than what is possible with straight cables. At small transmission distances speeds up to 35Mbps can be realized with RS485 although the transmission speed will decrease with distance.

The capacitance is close to 12.5 pF/foot but there is a small impedance mismatch (100 ohms for Cat 5, 120 ohms for RS-485). 100 ohms, Cat 5 cables almost meets the electrical requirements for RS-485 cables. Because they are produced in such large quantities, Cat 5 cables are relatively inexpensive, often less than half the price of specialty RS-485 cabling. RS-485 is also used in building automation as the simple bus wiring and long cable length is ideal for joining remote devices. 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. To ensure that no two devices drive the network at the same time, it is necessary that each slave device be able to disable its own RS485 data transmitter.