RS485 is simpler because it uses only two wire (or a single pair) to carry out the data in bidirectional manner, using RS232, we need 3 wires at minimum to carry the data bidirectionally. Owing to hardware constraints, if modem handshaking is needed on UART channel 1, then channel 1 must be configured for RS232, rs485 cable and channel 2 cannot be configured for RS232 communications. In order to avoid signal reflections, a 120 Ohm termination resistance must be fitted on each end of the main cable. End of line termination resistor (120 ohm 1/4 watt) to be installed at both ends of network. 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. The cable which I have used in the tutorial is 25m in length. Could I have detailed instructions on WIN 11? 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.

It is however more likely to be serial side problems. 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. Each serial port can be configured for the RS232 or RS485 protocol, and runs at standard baud rates up to 115,200 bits per second. Its simplest implementation requires only three wires: one to transmit serial data, a second to receive serial data, and a third to provide a common ground reference. 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. Category 5 (Cat 5, Cat 5e, and Cat 6) cables are the most common Ethernet cables in use today. Sig- lines are twisted as twisting nullify the effect of electromagnetic noise induced in a cable and provide a much better immunity against the noise which allows the RS485 to transmit the data up to 1200m of range.

The RJ11 connector can be used for both RS232 and RS485. These cables allow the dual RJ11 jacks of the RS485 option board of Laureate meters (digital interface ordering option 2) to be daisy chained and to be addressed digitally with no need for a hub. 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. Signal High and Lows are measured against the GND level so shifting the GND level will have a disastrous effect on the data transfer. At small transmission distances speeds up to 35Mbps can be realized with RS485 although the transmission speed will decrease with distance. 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. For the transfer of data, the baud rates of both Master and Slave must be between 10% of each other.

Polarity of the wires must be observed. 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). The below image shows the transmitter and receiver circuit diagram for Arduino's long-distance wired communication. The connection diagram for the above circuit is also given below. The RS485 receiver compares the voltage difference between both lines, instead of the absolute voltage level on a signal line. If the /SS pin of the master is an input and if a low input level is detected, the processor sets the MODF bit in the SPI status register a "mode fault" condition. The MODF bit is cleared by a read of the SPSR followed by a write to the SPCR. RS232 uses inverse logic; that is, a positive bit at the 68HC11 UART is inverted by the onboard RS232 driver chip and appears as a negative signal on the serial cable. 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.