Product description: Dual-channel RS485 Expansion Hat - two-channel shield for Raspberry Pi 4B - DFRobot DFR0824
Dual-channel RS485 Expansion Hat is an overlay designed for the Raspberry Pi 4B minicomputer. It was designed to extend the functionality of the module with RS485 communication and thus increase the reliability of connections and prevent possible interference in data transmission. The shield has been equipped with protection circuits, such as lightning and surge protection, it also has a TVS diode and power supply isolation. In the extreme part of the board there are pins in the form of screw connectors that enable simple and quick connection with other peripheral devices.
Product compatible with Raspberry Pi 4B!
Also check the manufacturer's user guide .
The subject of the sale is a two-channel shield for Raspberry Pi 4B. Raspberry Pi must be purchased separately.
Module that converts data from the UART serial interface to RS485 protocol frames.
What is RS485?
RS485 is one of the most commonly used serial communication standards, which is characterized by very good noise suppression, the ability to transmit data over long distances (without loss of transmission quality), as well as multi-drop capabilities. This standard uses daisy-chain transmission (so-called linear topology), which allows suppression of common-mode interference.
What is Modbus?
Modbus is a protocol of master / slave architecture, which is used in the case of communication between devices via the RS485 standard. Modbus uses unique addresses for each slave device (peripheral device, e.g. sensor) to execute commands from the master device (executor module, e.g. Raspberry Pi). Modbus commands contain a control code that ensures data integrity and can be used to change register values, control or read I/O ports, and retrieve data from devices.
Special features of the module
- Two-channel RS485 shield for Raspberry Pi 4B
- Electrical and signal isolation
- Lightning and surge protection
- Transient voltage suppressor
- RX/TX data transmission and reception indicator
Arrangement of components on the board
- 40-pin Raspberry Pi connector for connecting the board.
- RS485 interface (GND, A1, B1, A2, B2 are connected to the corresponding RS485 port).
- Terminating resistors 120 Ohm - during long-distance RS485 communication, there may be a distorted signal, at this time a 120 Ohm resistor should be connected. Normally, set it to the NC pin.
- The RX/TX indicator of the respective port will flash during RS485 communication; TX in blue and RX in green.
Example connection diagram.
Dual-channel RS485 Expansion Hat - two-channel shield for Raspberry Pi 4B - DFRobot DFR0824.
Module technical specification
- Operating voltage: 3.3V
- Built-in RS485 transceiver: TP75176E
- Serial chip: CH432T
- Communication interface: RS485 x2
- Power indication: red LED
- TX communication signaling: blue LED
- RX communication signaling: green LED
- Terminal resistance: 120 Ohm x2
- Terminals: terminal strip (screw connector) 3-pin, raster 5.08 mm
- Compatibility: Raspberry Pi 3B+ / 4B
- Mounting hole diameter: 2.5 mm
- Board dimensions (measured without screw connections): 56 x 65 mm
Suggested use
- IoT in agricultural applications
- IoT in warehouse applications
- Monitoring of the internal and external environment
- Lighting control
- Security control system
Kit contents
- Dual-channel RS485 Expansion Hat - two-channel shield for Raspberry Pi 4B - 1 piece
- Mounting screws - 8 pieces
- Spacer sleeves - 4 pieces
Kit contents.
