Twisted pair also allows the transmission speeds to be much higher than what is possible with straight cables. The two-wire half-duplex system enables bidirectional data transmission between two devices, but not simultaneously. As it is a half-duplex IC hence it can not both transmit and receive at the same time. At small transmission distances speeds up to 35Mbps can be realized with RS485 although the transmission speed will decrease with distance. The differential voltage system also allows the RS485 to provide longer data transfer distance and lower voltage use, which helps to increase data speed. Easy to Use: The sensor can be used out-of-box through Bluetooth configuration, and users receive the data on the phone, cloud servers, what is rs485 cable and different platforms in just a few clicks. Powerful APP Support: SenseCAP Mate APP allows you to set the sensor templates and quickly turn the data logger into the sensor you want. Then use front panel programming to set the baud rate, protocol, digital address, half or full duplex, and other available parameters.
After a data transfer is initiated by writing to the SPDR data register, the processor may poll the SPSR status register until the SPIF flag is set. However, in electrically noisy environments with different potential levels, RS232 is too fragile and allows data corruption. 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. 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. 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. Shown below is the example of how a character is a transmitter over a UART data line. 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.
With this boards, a CBL03 lines with RJ11 connectors can branch out to support an RS485 line consisting of three discrete wires. 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. Cross-linked polyethylene (XLPE) or Polyvinyl Chloride (PVC) is the material used for this layer. This UART-RS485 Converter module has an on-board MAX485 chip which is a low-power and slew-rate-limited transceiver used for RS-485 communication. In theatre and performance venues, RS-485 networks are used to control lighting and other systems using the DMX512 protocol. If the 68HC11 is initialized as a master (by setting the MSTR bit in the SPCR control register as explained below) then bit 5 of the Port D data direction register (DDRD) determines whether /SS is an input or an output.
Clearing the MSTR bit in the SPCR control register automatically configures the /SS (slave select) pin as an input. It is very well documented and widely used and it also has a parity bit to allow for error checking. With RS232 well established and the need for faster communications and over longer distances, further standards beyond RS232 were introduced. 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. 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 will also initialize the LCD here and print a welcome message. Here again, 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. It operates on a differential signaling method of measurement rather than voltage measurement wrt GND pin.
