We will pull the enable pin high to put the MAX485 module in receiver mode. 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. It converts TTL signals to and from the differential RS485 signals. RS-485 signals transmit on a serial bus, meaning all senders (masters or managers) will be detected by all receivers. 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. 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. 2 Alphanumeric LCD connected to it. So, in the Arduino code, we will focus on sending the data and display that sent or received data on the LCD screen. A few people have said you shouldn't terminate the screen of more than one device on the network as it would cause ground loops. Out of those terminal blocks along another cable for about 10ft and then into some more terminal blocks.

Systems of this type (4-wire, half-duplex) are often constructed to avoid "data collision" (bus contention) problems on a multi-drop network (more about solving this problem on a two-wire network in a moment). The recommended arrangement of the wires is as a connected series of point-to-point nodes, a line or bus. 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). The circuit diagram given above explains how the onboard MAX485 IC is connected to various components and provide 0.1-inch standard spacing headers to be used with breadboard if you like. The below image shows the transmitter and receiver circuit diagram for Arduino's long-distance wired communication. Do note that both transmitter and receiver circuits look identical the only thing that differs is the code written into it. One other thing to check is to be sure your serial port is properly enabled. The maximum sustainable baud rate on the secondary serial port is 4800 baud. The QScreen Controller has two serial communications ports: a primary serial port called Serial 1 that supports both RS232 and RS485 protocols, rs485 cable and a secondary serial port called Serial 2 that supports RS232.

Although the RS232 protocol specifies functions for as many as 25 pins, each communications channel requires only three for simple serial interfaces: TxD1 (transmit data), RxD1 (receive data), and DGND (digital ground). Given the availability of ready-made communications cables, it is not necessary to study or understand the following descriptions of cable connections. This is an extra single bit appended to the end of each byte or character transmitted, which is set or cleared as necessary to ensure that the total number of '1' bits in the byte is always odd or even. So, for eight data bits with a parity bit, M would be set (equal to one) in order to add an extra bit to each byte transmitted, and PE would be set in order to make that extra bit be used as a parity bit. Therefore the pin assignment is a little bit different from the default pin assignment on the RJ11 socket.

The DWOM bit determines whether Port D needs pull-up resistors; it should be set to 0. The MSTR bit determines whether the device is a master or slave. I have to communicate with rs485 based energy meters which are 100-130 meters from location where gateway device is placed. For shipping quotes, "Checkout" the item you want to buy, enter your shipping details and the shipping rates will automatically generate based on the item's weight and the delivery location. There is also the GSM version; especially useful when only one sensor is needed in a remote location where other types of transmission cannot be used. In this project, we have only used a baud rate of 9600 which is well under the maximum transfer speed we can achieve with the MAX-485 Module but this speed is suitable for most of the sensor modules out there and we don’t really need all the maximum speeds while working with Arduino and other development boards unless you are using the cable as an ethernet connection and require all the bandwidth and transfer speed you can get. This connection may be used to limit the common-mode signal that can be impressed on the receiver inputs.