What is RS485?

RS485 is a common serial communication standard with features such as good noise rejection, long transmission distance, and multi-drop capability. It transmits data using a differential transmission method, which allows it to suppress common-mode interference. RS485 requires a pair of twisted-pair cables and two terminal resistors to eliminate signal reflection during long-distance communication.

What is the Modbus Protocol?

Modbus is a master/slave architecture protocol used for communication between devices over RS-485. It uses unique addresses for each slave device to execute commands from a master device. Modbus commands include a check code to ensure data integrity, and can be used to change values in registers, control or read I/O ports, and retrieve data from devices.

Raspberry Pi RS485 HAT Introduction

This dual-channel RS485 expansion HAT designed for the Raspberry Pi adopts an isolated transceiver to achieve isolation for RS485, which increases the reliability and anti-interference of data transmission in each channel. And it features embedded protection circuits such as a lightning and surge protector, a TVS diode, and power supply isolation to protect the Raspberry Pi development board effectively.

Besides, the order includes a screw accessory kit that allows users to tightly fix this board onto a Raspberry Pi controller.

Wiring Diagram of RS485 Expansion HAT and Laser Ranging Sensor