# Dual-channel RS485 Expansion Hat for Raspberry Pi 4B

**Type:** Product page · **SKU:** DFR0824 · **Brand:** [DFRobot](https://core-electronics.com.au/brands/dfrobot-australia)
**Page:** https://core-electronics.com.au/dual-channel-rs485-expansion-hat-for-raspberry-pi-4b.html ([markdown](https://core-electronics.com.au/dual-channel-rs485-expansion-hat-for-raspberry-pi-4b.html.md))

Want to increase reliability and anti-interference for data transmission in your industrial applications? Try the RS485 Expansion HAT for Raspberry Pi....

## Pricing

- **Price:** $50.25 (inc GST) — $45.68 AUD, exc GST
- **Quantity discounts:** 6+ $43.40 (exc GST) · 12+ $41.57 (exc GST)

## Availability & dispatch

- Available with a lead time — expect dispatch between Aug 31 and Sep 02.

## Description

**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](https://www.dfrobot.com/category-269.html) designed for the [Raspberry Pi](https://core-electronics.com.au/raspberry-pi.html) 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](https://www.dfrobot.com/topic-272-184.html) 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](https://core-electronics.com.au/attachments/localcontent/Connection-Diagram_12723c0912d.png)**

**Wiring Diagram of RS485 Expansion HAT and Laser Ranging Sensor**

### Features

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

- Agricultural Internet of Things
- Warehouse Internet of Things
- Indoor and Outdoor Environmental Monitoring
- Lighting Control
- Security Access Control System
 
### Specification

- 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
- 120O 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”
 
### Documents

- [Product wiki](https://wiki.dfrobot.com/SKU_DFR0824_RS485_Expansion_HAT_for_Raspberry_Pi)
- [Schematics](https://core-electronics.com.au/attachments/localcontent/18e31c27d0e3d47e5cbf3b717e3ad190_291194de5d7.PDF)
- [Design Document](https://core-electronics.com.au/attachments/localcontent/515a0209d86fcbf9afcc2a32d6abeaaf_24118523872.rar)
- [Model File](https://core-electronics.com.au/attachments/localcontent/206232d618afa04e69fac7418fc5abf8_88372b6b441.rar)
- [CAD File](https://core-electronics.com.au/attachments/localcontent/5b85f226b5b081ddff5c5d5abe6b33ed_12041e9da38.rar)
- [TP75176E Datasheet](https://core-electronics.com.au/attachments/localcontent/cf318d0de115098e8aa88f5806c6d6cd_15285955d0b.PDF)
 
### Parts List

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

## Images

- [Product image 1](https://core-electronics.com.au/media/catalog/product/D/F/DFR0824-1.jpg)