{"id":3097,"date":"2023-09-08T12:29:10","date_gmt":"2023-09-08T12:29:10","guid":{"rendered":"https:\/\/vegaprocessors.in\/blog\/?p=3097"},"modified":"2023-09-08T12:29:10","modified_gmt":"2023-09-08T12:29:10","slug":"how-to-interface-aries-boards-using-rs485-modbus-protocol","status":"publish","type":"post","link":"https:\/\/vegaprocessors.in\/blog\/how-to-interface-aries-boards-using-rs485-modbus-protocol\/","title":{"rendered":"How to interface ARIES boards using RS485 (Modbus) protocol"},"content":{"rendered":"\n

In this tutorial, we will discuss how to communicate between two ARIES boards with the help of the RS485 (Modbus RTU) serial data communication protocol.  We will follow the RS485 master-slave communication method. For demonstration purposes, we will create a project that will ON or OFF a LED connected to a Slave ARIES from Master ARIES by sending some commands through RS485 Module. The master ARIES uses a push button to control the LED attached to the slave device.<\/p>\n\n\n\n

MAX485 TTL to RS485 Module<\/strong><\/h2>\n\n\n\n

For using RS-485 in ARIES, a module called MAX485 TTL to RS485 <\/strong>which is based on Maxim MAX485 IC<\/strong> is needed as it allows serial communication over long distance.The MAX485 TTL to RS-485 Interface Module allows MCUs to use the RS-485 differential signaling for robust long distance serial communications. ARIES boards doesn\u2019t have any peripherals for Modbus communication. We will use an RS485-based sensor module called MAX485 for communication between two ARIES boards. The MAX485 pin description is given in the following table:<\/p>\n\n\n\n

Pin Name<\/strong><\/td>Description<\/strong><\/td>Function<\/strong><\/td><\/tr>
RO<\/td>Receiver Output<\/td>Connects to a serial RX pin on the microcontroller<\/td><\/tr>
RE<\/td>Receiver Enable <\/td>Active LOW.  Connects to a digital output pin on a microcontroller. Drive LOW to enable receiver, HIGH to enable Driver<\/td><\/tr>
DE<\/td>Driver Enable  <\/td>Active  HIGH.  Typically jumpered to RE Pin.<\/td><\/tr>
DI<\/td>Driver Input<\/td>Connects to serial TX pin on the microcontroller<\/td><\/tr>
VCC<\/td>Voltage Common Collector<\/td>supply pin<\/td><\/tr>
A<\/td>Data \u2018A\u2019 Non-Inverted Line <\/td>Used as non-inverting receiver input and inverting driver output<\/td><\/tr>
B<\/td>Data \u2018B\u2019 Inverted Line<\/td>Used as inverting receiver input and inverting driver output<\/td><\/tr>
GND<\/td>Ground<\/td>Ground<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Modbus Protocol<\/h2>\n\n\n\n

Modbus is a serial communication protocol developed by Modicon published by Modicon in 1979 for use with its programmable logic controllers (PLCs). In simple terms, it is a method used for transmitting information over serial lines between electronic devices. The device requesting the information is called the Modbus Client and the devices supplying information are Modbus Servers. <\/p>\n\n\n\n

RS485<\/h2>\n\n\n\n

Modbus communicates over different types of physical media and they are:<\/p>\n\n\n\n