Resource

Demo

• Demo code

Software

• SSCOM

Overview

Electrical Safety Precautions

• This product should be operated and used by professional electricians or technical personnel. Please ensure electrical safety measures are in place, including protection against leakage and insulation.
• Before installing, maintaining, or replacing relay equipment, always turn off the power and unplug the plug.
• Do not attempt to dismantle relay equipment to avoid damaging the device or risking electric shock.
• Please properly install and place relay equipment. Avoid use in damp, overheated, or flammable environments to prevent accidents caused by improper installation or use.

This is an industrial 8-ch relay module controlled via RS485 bus, with 8-ch digital input, utilizing Modbus RTU protocol. It features embedded protection circuits such as power isolation, magnetical isolation, TVS diode, etc. It also comes with an ABS enclosure. The Modbus RTU Relay (D) is very easy to use. Due to its fast communication, stability, reliability, and safety, it is an ideal choice for industrial control equipment and/or applications with high communication requirements.

Parameters

Primary Functions

Supports reading digital input by sending Modbus RTU protocol commands via RS485 for digital output control.

Wiring Description

• DI1-DI8 is the 8-ch signal input terminal, and DGND is the ground signal. COM is the common terminal for the input signal, NC, or power supply positive or negative, can be directly from the power supply, and can also be connected to an independent power supply power supply.
• NC: dry contact passive input.
• Connect to the power supply positive: low active, NPN wet contact active input, voltage: 5V-30V DC.
• Connect to the power supply negative: high active, PNP wet contact active input.

Digital Input Wiring

Passive Dry Contact Wiring

• Passive dry contact input:

Active Wet Contact Wiring

• Active wet contact NPN input

• Active wet contact PNP input

Relay Output Wiring

The device comes with a relay with a contact capacity of 10A 250V AC or 10A 30V DC, which allows direct control of household 220V AC equipment or DC equipment up to 30V.

Dimensions

Hardware Test

RS485 Test

• Connect the USB TO 485 to the target board through wires, A-A and B-B as shown below:

• Download SSCOM and open it on the computer, open the corresponding port number, and set the baud rate as 9600. Clicking on multiple strings will open multiple string-sending windows. Clicking on the corresponding function will send the corresponding command.
• If you need to send other commands then select HEX to send, plus check select ModbusCRC16 checksum, enter the first six bytes of the command, and click send then the CRC checksum will be added automatically.

• For detailed control commands, please see the development protocol.

Demo Test

Note: RS485 can not be directly connected to the serial port of the Raspberry Pi, otherwise it may burn the device, you need to add 485 level conversion, the Raspberry Pi is recommended to use with the RS485 CAN HAT module, NUCLEO-F103RB, and Arduino is recommended to use with the RS485 CAN Shield module!

Raspberry Pi

Open the Raspberry Pi terminal and input the following commands to enter the configuration interface.

sudo raspi-config
Select Interfacing Options -> Serial Port, select Yes to open the hardware serial port 

And then reboot the Raspberry Pi:

sudo reboot

Insert the RS485 CAN HAT into the Raspberry Pi, and connect the Modbus RTU Relay module to the RS485 CAN HAT through A and B.
If you are using other 485 devices, you need to make sure A-A, B-B.
Run the following commands:

sudo apt-get install unzip
wget https://files.waveshare.com/wiki/Modbus-RTU-Relay-(D)/Modbus_RTU_Relay_D_Code.zip
unzip Modbus_RTU_Relay_D_Code.zip
cd Modbus_RTU_IO_Code/Python3
sudo python3 main.py

After the demo normally runs, each channel can be opened and closed in order, and the current input status is displayed.

STM32

The STM32 demo is based on the NUCLEO-F103RB and RS485 CAN Shield module.
Find the STM32 demo file directory and open the STM32 project. Please note that the keil5 software is installed before use, and download the demos to the development board.
After running normally, each channel can opened and closed in order. The serial port will output the commands to be sent and finally display the current input status.

Arduino

The Arduino demo is based on the UNO PLUS and RS485 CAN Shield module.
Use the Arduino IDE to open the demo, select the corresponding development board, and download the demos.
After running normally, each channel will open and close in order. The serial port will output the commands to be sent and finally display the current input status.

Development Protocol

Resource

Demo

• Demo code

Software

• SSCOM

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