Both the Profibus and the RS485 are standards used in communication during process automation. It is basically a standard of fieldbus communication used in automation technology. Differential pairs may host up to 32 devices on the standard that uses twisted pairs and a reference. The temperature sensor DS18B20 is a digital temperature sensor, because to transmit the information it uses the protocol 1 - Wire. It allows communication over long distances and uses twisted pair cable. It allows network communication in point-to-point mode and suffers more from electromagnetic interference. For all of this equipment to work together, it is essential that there is a communication network between them. There are two versions of the standard being used in industries. When an SMINI is talking to the PC, the SMINI card’s U7 transmit IC is in effect operating in a low impedance state driving the two bus lines with ‘1s’ and ‘0s’. It seems that the common-mode impedance for the 100 Ω cable (differential impedance of each pair) is around 25 Ω. The receiver input circuit includes electro-static discharge (ESD) protection, a resistor-divider network, and biasing current, influencing the magnitude and common-mode voltage reaching the differential comparator. This cable model reduces electromagnetic interference since we have a differential communication signal and this contributes to being more immune to noise and electromagnetic interference.

It is necessary to use a pull-up resistor of 4K7 between the VCC and the signal pin of the DS18B20 sensor so that the communication between the microcontroller and the sensor is stable. The microcontroller is the master and the peripherals are the slaves. One of them is Profibus DP which stands for Decentralised Peripherals and the other is Profibus PA which stands for Process Automation. Profibus DP is meant to be used to control and operate sensors and actuators through a centralized platform for automation applications in production industries and factories. Now people who do have a fair idea about the whole data exchange system in industrial networking would know that these are two very important contributors for smooth process automation. So in this article, we will learn how to monitor the temperature of an environment and receive the measured value through serial / RS485 communication between two Arduinos. Thus, RS485 communication can be used in any type of environment due to its robustness. However, the industry is an environment that suffers from the presence of many electromagnetic interferences due to the activation of motors, solenoids, and other actuators.

In one revision we did just like that, but it turned out to be a fail… Like much of the RS-485 standard, fail-safe operation is left wide open and implementation is not part of the standard. Many people recommend writing prototype software as if it will be connected to a half-duplex RS-485 network. It does not specify or recommend any communications protocol; Other standards define the protocols for communication over an RS-485 link. And field bus refers to the network protocols used for real-time distributed control. The RS485 communication standard is the physical layer of the communication network, and several protocols such as Modbus, Profibus, and others can be implemented. The SMINI and the SUSIC are designed to operate with standard baud rates of 9600, 19200, 28800, 57600 and 115200 bits per second or bps. It is important to understand that all four serial interface standards allow different baud or data-transmission rates. In reality, if you are using relatively modern equipment (say 1990 or later) and a low baud rate, line lengths of 1,000 feet (300 m) or more are possible. The Arduino Slave (Transmitter) will perform the temperature measurement using a DS18B20 digital sensor and will send this measured value via serial / RS485 to the Arduino Master (Receiver) that will write on the LCD display 20 x 4 I2C the received temperature value.

I2C libraries responsible for I2C communication and communication with the I2C LCD display. Write a message on the LCD display. Lcd object, in these objects we have to put the display address. In the void setup we start the communication with the LCD display, we configure as a pin the output that enables or not the reception of data through RS485 communication. The current-sinking output format should work for most applications. Your circuit with the BJT won't work. On the left, we have the receiver circuit and on the right the transmitter. Data Terminal Ready (DTR): The Receiver tells the Sender it is ready to send or receive data. Next, we need declare a variable for interfacing MAX485 TTL To RS4485 module RE and DE terminal with ESP32 board. Next, we will present the complete code of the receiving circuit. First, we have the complete code of the receiving circuit. This integrated circuit plays a role in adapting the TTL logic level to the logic level required for RS485 communication.

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