Dual-channel RS485 Expansion HAT

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

• Dual Channel RS485
• Electrical & signal isolation
• Lightning & surge protection
• Transient voltage suppressor
• RX/TX data transmitting/receiving indicator

• Agricultural Internet of Things
• Warehouse Internet of Things
• Indoor and Outdoor Environmental Monitoring
• Lighting Control
• Security Access Control System

• Operating Voltage: 3.3V
• RS485 Transceiver: TP75176E
• Serial Chip: CH432T
• RS485 Communication Interface ×2
• Power Indicator: red
• TX Communication Indicator: blue
• RX Communication Indicator: green
• 120Ω Terminal Resistance: ×2
• Wiring Method: 5.08-3P pluggable terminal block
• Raspberry Pi 3B+/4B Supported
• Mounting Hole Size: diameter 2.5mm
• Dimension(Package Not Included): 56×65mm/2.20×2.56”

• Product wiki
• Schematics
• Design Document
• Model File
• CAD File
• TP75176E Datasheet

• RS485 Expansion HAT for Raspberry Pi ×1
• Copper Column & Screw ×4