Modbus RTU Relay 32CH Relay Module

Мушаххасоти

• Номи маҳсулот: Modbus RTU Relay 32CH
• Мутобиқат: Raspberry Pi, STM32, Arduino
• Пайвастшавӣ: RS485

Барview

Electrical and Relay Safety Instructions 

• This product must be operated by professional electricians or qualified personnel. During use, ensure electrical safety, leakage protection, and proper insulation.
• Before installing, maintaining, or replacing the relay device, always turn off the power and unplug the device.
• Do not attempt to disassemble the relay device to avoid damage or the risk of electric shock.
• Properly install and place the relay device. Do not use it in humid, overheated, flammable, or explosive environments to prevent accidents caused by improper installation or use.

Мутобиқсозии бор

• Ensure the relay’s rated voltage and current match the load. Do not exceed the rated capacity.
• For inductive loads (motors, coils, lamps, etc.), the starting current may be much higher than the rated current. Choose a relay with sufficient current margin.

Ҳимояи ноқилҳои кӯтоҳ ва аз ҳад зиёд

• Install a fuse or circuit breaker in the relay circuit to prevent damage due to short circuits or accidental overcurrent.
• Ensure the load circuit has no short circuits during wiring, and select protection components with appropriate current ratings if necessary.

Arc and Switching Protection

• Relay switching generates arcs, which can cause contact wear or welding.
• For inductive loads, it is recommended to use RC snubber circuits or varistors for arc suppression.

Муҳити насб

• Do not use the relay in humid, high-temperature, flammable, explosive, or dusty environments.
• Install the relay securely to avoid vibrations or shocks that may cause misoperation or damage.

Power-Off Operation

• Always cut off power before maintenance, wiring, or replacing the relay to ensure personnel and device safety.
• Latching relays are only powered when changing state. Avoid strong vibrations or strong magnetic fields while the relay is unpowered.

Тасдиқи ҳолати

• After powering on, confirm or reset the relay status as needed to prevent abnormal operation caused by transportation, installation, or external disturbances.
• Avoid power interruption during relay operation to prevent uncertain status or contact damage.

Санҷиши мунтазам

• Periodically inspect relay contacts, terminals, and insulation to ensure proper operation.
• If abnormal heating, odor, or burn marks are detected, immediately cut off power and replace the relay.

Пайвастагии сахтафзор

Example Demonstration

• The demo shows how the following two software operate. SSCOM serial port debugging assistant is more convenient to operate, free of installation, and more convenient for complete display and analysis of instructions, but the disadvantage is that the data is not intuitive. Modbus Poll software is directly operated on the register, and the data display is more convenient to observe, but the disadvantage is that the instruction is not displayed completely, so you need to be familiar with the Modbus register operation.
• You can test using any method. It is recommended to use the SSCOM serial port debugging assistant software for the first test.

SSCOM Serial Port Debugging Assistant

• Download SSCOM Serial port debugging assistant and open it on the computer, open the corresponding port number, and set the baud rate as 9600. Click Multi-Char to open the Send Multi-Char window, and click the function to send the corresponding command.
• If you need to send other commands, choose SendHEX. For checksum validation, select ModbusCRC16. After entering the first six bytes of the command, clicking SEND will automatically add the CRC check code.
• For detailed control commands, please see the development protocol.

Modbus Poll Software 

• It is not convenient to use the SSCOM software for observing the data, you can select Modbus Poll software to read the data. Download and install the Modbus Poll software.
• Open the software, select Setup->Read/Write Definition, select the actual device address for Slave ID, select 01 Read Coils function code for Function, and change Quantity to 32 channels. Click OK to confirm.
• Select Connection->Connect…, choose the corresponding serial port, set the baud rate to 9600, and select 8 Data bits and None Parity. Click OK to connect.
• After the connection is normal, you can check the current relay status. Select the corresponding channel, then double-click the status value to pop up the send page. Choose On or Off, then Click Send to control the relay opening and closing.

Санҷиши намоишӣ 

• 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. For Raspberry Pi, it is recommended to work with the RS485 CAN HAT module. For NUCLEO-F103RB and Arduino, it is recommended to work with the RS485 CAN Shield module.

Raspberry Pi 

• Open the Raspberry Pi terminal and enter the following command to enter the configuration interface
• Then restart Raspberry Pi:
• /boot/config.txt -ро кушоед file, find the following configuration statement to enable the serial port, if not, you can add it to the end of the file.
• For Raspberry Pi 3B users, the serial port is used for Bluetooth and needs to be commented out:
• Then restart Raspberry Pi:
• 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, make sure to connect A-A, B-B. Run the following commands to run the demo:

STM32

Note: The STM32 demo is based on the NUCLEO-F103RB and RS485 CAN Shield module.

1. Download Demo, find the STM32 project file Modbus Relay.uvprojx in the path Modbus_RTU_Relay_32CH_Code\STM32\MDK-ARM, and double-click to open the STM32 project file. Note that you should ensure Keil5 software is installed on your computer before using it.
2. Connect the STM32 to a computer via the STM32 download and debug probe. Compile and download the program to the development board.
3. Install the RS485 CAN Shield module on the STM32. Connect the RS485_A on the RS485 CAN Shield module to the RS485_A on the Modbus RTU Relay via a wire, and connect the RS485_B on the RS485 CAN Shield module to the RS485_B on the Modbus RTU Relay via a wire. Then power on the Modbus RTU Relay and the STM32 sequentially.
4. After powering on, the serial port will output the transmitted commands, which can be observed using a serial port assistant. Meanwhile, the relays will sequentially turn on (e.g., 1→2→3→4). Once all relays are fully activated, they will then sequentially turn off (e.g., 1→2→3→4). You can observe whether the relay is normally engaged through the LED indicator light.

Arduino 

Note: The Arduino demo is based on the UNO PLUS and RS485 CAN Shield module.

1. Download Demo, find the Arduino project file Modbus_RTU_Relay.ino in the path Modbus_RTU_Relay_32CH_Code\Arduino\Modbus_RTU_Relay, and double-click to open the Arduino project file. Note that you should ensure Arduino IDE software is installed on your computer before using it. 
2. Connect the Arduino to the computer via a USB cable. In the Arduino IDE software, select the Arduino board model under Tools->Board. Choose the COM port that the Arduino is connected to under Tools->Port.
3. After seeing the prompt to connect to the computer in the lower right corner, click to compile and flash the program, and wait for the flashing to complete.
4. Install the RS485 CAN Shield module on the Arduino. Connect the RS485_A on the RS485 CAN Shield module to the RS485_A on the Modbus RTU Relay via a wire, and connect the RS485_B on the RS485 CAN Shield module to the RS485_B on the Modbus RTU Relay via a wire. Then power on the Modbus RTU Relay and the Arduino  sequentially.
5. After powering on, the serial port will output the transmitted commands, which can be observed using a serial port assistant. Meanwhile, the relays will sequentially turn on (e.g., 1→2→3→4). Once all relays are fully activated, they will then sequentially turn off (e.g., 1→2→3→4). You can observe whether the relay is normally engaged through the LED indicator light.
   Шарҳ: The data in the figure below is in ASCII code containing spaces and line breaks, and is not the actual data sent.

PLC 

Note: The PLC demo is based on SIMATIC S7-200 SMART.

1. Download Demo, find the PLC project file modbus_rtu.smart in the path Modbus_RTU_Relay_32CH_Code\PLC, and double-click to open the PLC project file. Note that you should ensure STEP 7-MicroWIN SMART software is installed on your computer before using it.
2. Connect the PLC to the computer via a network cable. Click to download
3. Select the communication interface in the communication popup, find your device, and click Confirm
4. In the download pop-up window, check the boxes for program blocks, data blocks, and system blocks, and then click Download.
5. Connect the 485_A on the PLC module to RS485_A on the Modbus RTU Relay with a wire, and connect the 485_B on the PLC module to RS485_B on the Modbus RTU Relay with a wire. Then power on the Modbus RTU Relay.
6. After powering on the Modbus RTU Relay, in the STEP 7-MicroWIN SMART software, find the “PLC” tab in the upper menu bar, switch to this tab, and click the green “RUN” button in the lower “Operation” area to perform the operation to make the PLC enter the running state
7. After the PLC runs, the relays will sequentially turn on (e.g., 1→2→3→4). Once all relays are fully activated, they will then sequentially turn off (e.g., 1→2→3→4). You can observe whether the relay is normally engaged through the LED indicator light.

Development Protocol V2

Муқаддимаи рамзи функсия

Кодекси функсия	Тавсифи	Шарҳ
01	Ҳолати чархро хонед	Read relay status
03	Феҳристи нигоҳдорӣ хонед	Read the address and version
05	Як катро нависед	Write single relay
06	Реестри ягона нависед	Set the baud rate and address
0F	Якчанд сатрҳо нависед	Write all relays

Register Address Introduction

Address (HEX)	Адрес storage content	Бақайдгирии арзиш	Иҷозат	Функсияи Modbus Кодекс
0х0000 …… 0x001F	Channels 1~32 relay addresses	0xFF00: relay on 0x0000: relay off 0x5500: relay toggle	Хондан/навиштан	0x01, 0x05, 0x0F
0x00FF	Control all relays	0xFF00: all relays on 0x0000: all relays off 0x5500: all relays toggle	нависед	0х05
0х0100 …… 0x011F	Channels 1~32 relays toggle	0xFF00: relay toggle 0x0000: relay unchanged	нависед	0x05, 0x0F
0x01FF	All relays toggle	0xFF00: all relays toggle 0x0000: all relays unchanged	нависед	0х05
0х0200 …… 0x021F	Channels 1~32 relays flash on	Delay time: data*100ms Value: 0x0007, delay time: 7*100MS = 700MS	нависед	0х05
0х0400 …… 0x041F	Channels 1~32 relays flash off	Delay time: data*100ms Value: 0x0007, delay time: 7*100MS = 700MS	нависед	0х05
4×2000	UART Параметр	The high eight bits indicate the parity mode: 0x00~0x02 The low eight bits indicate the baud rate mode: 0x00~0x07	Хондан/навиштан	0x03, 0x06
4×4000	Суроғаи дастгоҳ	Directly store Modbus address Device address: 0x0001-0x00FF	Хондан/навиштан	0x03, 0x06
4×8000	Версияи нармафзор	Converting to decimal and then shifting the decimal point two places to the left will represent the software version 0x0064 = 100 = V1.00	Хондан	0х03

Modbus RTU Command Introduction

Control Single Relay

• Send code: 01 05 00 00 FF 00 8C 3A

Майдон	Тавсифи	Шарҳ
01	Суроғаи дастгоҳ	0x00 indicates the broadcast address, 0x01-0xFF indicates the device address
05	05 Фармон	Назорати реле
00 00	Адрес	The register address of the relay to be controlled, 0x0000-0x001F
FF 00	Фармон	0xFF00: relay on; 0x0000: relay off; 0x5500: relay toggle
8С 3А	CRC16	The CRC16 checksum of the first 6 bytes of data

• Return code: 01 05 00 00 FF 00 8C 3A

Майдон	Тавсифи	Шарҳ
01	Суроғаи дастгоҳ	0x00 indicates the broadcast address, 0x01-0xFF indicates the device address
05	05 Фармон	Назорати реле
00 00	Адрес	The register address of the relay to be controlled, 0x0000-0x001F
FF 00	Фармон	0xFF00: relay on; 0x0000: relay off; 0x5500: relay toggle
8С 3А	CRC16	The CRC16 checksum of the first 6 bytes of data

• Барои мисолample: [Address 1 device]:

Control All Relays

• Send code: 01 05 00 FF FF 00 BC 0A

Майдон	Тавсифи	Шарҳ
01	Суроғаи дастгоҳ	0x00 indicates the broadcast address, 0x01-0xFF indicates the device address
05	05 Фармон	Назорати реле
00 FF	Адрес	Fixed 0x00FF
FF 00	Фармон	0xFF00: relay on; 0x0000: relay off; 0x5500: relay toggle
BC 0A	CRC16	The CRC16 checksum of the first 6 bytes of data

• Return code: 01 05 00 FF FF 00 BC 0A

Майдон	Тавсифи	Шарҳ
01	Суроғаи дастгоҳ	0x00 indicates the broadcast address, 0x01-0xFF indicates the device address
05	05 Фармон	Назорати реле

00 FF	Адрес	Fixed 0x00FF
FF 00	Фармон	0xFF00: relay on; 0x0000: relay off; 0x5500: relay toggle
BC 0A	CRC16	The CRC16 checksum of the first 6 bytes of data

• Барои мисолample: [Address 1 device]:

Read Relay Status

• Send code: 01 01 00 00 00 20 3D D2

Майдон	Тавсифи	Шарҳ
01	Суроғаи дастгоҳ	0x00 indicates the broadcast address, 0x01-0xFF indicates the device address
01	01 Фармон	Query relay status
00 00	Relay Start Address	The register address of the relay, 0x0000 – 0x001F
00 20	Рақами реле	The number of relays to be read, which must not exceed the maximum number of relays
3D D2	CRC16	The CRC16 checksum of the first 6 bytes of data

• Receive code: 01 01 04 00 00 00 00 FB D1

Майдон	Тавсифи	Шарҳ
01	Дастгоҳ	0x00 indicates the broadcast address, 0x01-0xFF indicates the device address

	Адрес
01	01 Фармон	Query relay status
04	Рақами байт	The number of all bytes of the returned status information
00 00 00 00	Ҳолати пурсиш	Received relay status The relay state is in small-endian format, with low bytes first and high bytes last Bit0: the first relay status; Bit1: the second relay status; And so on, with the idle high bit being zero
ФБ D1	CRC16	The CRC16 checksum of the first 6 bytes of data

• Барои мисолample: [Address 1 device]

Write Relay Status

• Send code: 01 0F 00 00 00 20 04 FF FF FF FF C5 1C

Майдон	Тавсифи	Шарҳ
01	Суроғаи дастгоҳ	0x00 indicates the broadcast address, 0x01-0xFF indicates the device address
0F	0F Command	Write relay status
00 00	Relay Start Address	The register address of the relay to be controlled, 0x0000 – 0x001F

00 20	Рақами реле	The number of relays to be operated, which must not exceed the maximum number of relays
04	Рақами байт	The byte number of the status
FF FF FF FF	Ҳолати реле	The relay state is in small-endian format, with low bytes first and high bytes last Bit0: the first relay status; Bit1: the second relay status; And so on, with the idle high bit being zero
C5 1C	CRC16	The CRC16 checksum of the first 6 bytes of data

• Receive code: 01 0F 00 00 00 20 54 13

Майдон	Тавсифи	Шарҳ
01	Суроғаи дастгоҳ	0x00 indicates the broadcast address, 0x01-0xFF indicates the device address
0F	0F Command	Control all registers
00 00	Relay Start Address	The register address of the relay to be controlled, 0x0000 – 0x001F
00 20	Рақами реле	The number of relays to be operated
54 13	CRC16	The CRC16 checksum of the first 6 bytes of data

• Барои мисолample: [Address 1 device]

Relay Flash ON/OFF Command

• Send code: 01 05 02 00 00 07 8D B0

Майдон

Тавсифи

Шарҳ

01	Суроғаи дастгоҳ	0x00 indicates the broadcast address, 0x01-0xFF indicates the device address
05	05 Фармон	Single control command
02	Flash on flash off	02: flash on, 04: flash off
00	Relay Address	The address of the relay to be controlled, 0x00~0x1F
00 07	Вақти таъхир	The delay time: data*100ms Value: 0x0007, delay time: 7*100MS = 700MS The maximum setting for the flash-on flash-off time is 0x7FFF
8D B0	CRC16	The CRC16 checksum of the first 6 bytes of data

• Receive code: 01 05 02 00 00 07 8D B0

Майдон	Тавсифи	Шарҳ
01	Суроғаи дастгоҳ	0x00 indicates the broadcast address, 0x01-0xFF indicates the device address
05	05 Фармон	Single control command
02	Flash on flash off	02: flash on, 04: flash off
00	Relay Address	The address of the relay to be controlled, 0x00~0x1F
00 07	Вақти таъхир	The delay time: data*100ms Value: 0x0007, delay time: 7*100MS = 700MS The maximum setting for the flash-on flash-off time is 0x7FFF
8D B0	CRC16	The CRC16 checksum of the first 6 bytes of data

• Барои мисолample: [Address 1 device]

Set Baudrate Command

• Send code: 01 06 20 00 00 05 42 09

Майдон	Тавсифи	Шарҳ
01	Суроғаи дастгоҳ	0x00 indicates the broadcast address, 0x01-0xFF indicates the device address
06	06 command	Set the baud rate and device address
20 00	Baud rate register	0x2000: set the baud rate
00	Parity Method	0x00: no parity, 0x01: even parity; 0x02: odd parity
05	Baud Rate Value	Correspondence of baud rate values 0x00: 4800 0x01: 9600 0x02: 19200 0x03: 38400 0x04: 57600 0x05: 115200 0x06: 128000 0x07: 256000
42 09	CRC16	The CRC16 checksum of the first 6 bytes of data

• Receive code: 01 06 20 00 00 05 42 09

Майдон	Тавсифи	Шарҳ
01	Суроғаи дастгоҳ	0x00 indicates the broadcast address, 0x01-0xFF indicates the device address
06	06 command	Set the baud rate and device address
20 00	Baud rate register	0x2000: set the baud rate

00	Parity Method	0x00: no parity, 0x01: odd parity; 0x02: even parity
05	Меъёри интиқол	Correspondence of baud rate values 0x00: 4800 0x01: 9600 0x02: 19200 0x03: 38400 0x04: 57600 0x05: 115200 0x06: 128000 0x07: 256000
42 09	CRC16	The CRC16 checksum of the first 6 bytes of data

• Барои мисолample: [Address 1 device]

Set Device Address Command

• Send code: 01 06 40 00 00 01 5D CA

Майдон	Тавсифи	Шарҳ
01	Суроғаи дастгоҳ	0x00 indicates the broadcast address, 0x01-0xFF indicates the device address
06	06 command	Set the baud rate and device address
40 00	Device address register	0x4000: set the device address
00 01	Суроғаи дастгоҳ	Set the device address, 0x0001-0x00FF
5D CA	CRC16	The CRC16 checksum of the first 6 bytes of data

• Receive code: 01 06 40 00 00 01 5D CA

Майдон	Тавсифи	Шарҳ
01	Суроғаи дастгоҳ	0x00 indicates the broadcast address, 0x01-0xFF indicates the device address
06	06 command	Set the baud rate and device address
40 00	Device address register	0x4000: set the device address
00 01	Суроғаи дастгоҳ	Set the device address, 0x0001-0x00FF
5D CA	CRC16	The CRC16 checksum of the first 6 bytes of data

• Барои мисолample: [Address 1 device]

Read Device Address Command

• Send code: 00 03 40 00 00 01 90 1B

Майдон	Тавсифи	Шарҳ
00	Суроғаи дастгоҳ	0x00 indicates the broadcast address, 0x01-0xFF indicates the device address
03	03 Фармон	Read the device address
40 00	Device address register	0x4000: read the device address
00 01	Рақами байт	Собит 0x0001

90 1B

CRC16

The CRC16 checksum of the first 6 bytes of data

• Receive code: 00 03 02 00 01 44 44

Майдон	Тавсифи	Шарҳ
00	Суроғаи дастгоҳ	0x00 indicates the broadcast address, 0x01-0xFF indicates the device address
03	03 Фармон	Read the software version and device address
02	Рақами байт	The number of bytes returned
00 01	Суроғаи дастгоҳ	Set the device address, 0x0001-0x00FF
44 44	CRC16	The CRC16 checksum of the first 6 bytes of data

• Барои мисолample: [Address 2 device]

Read Software Version Command

• Send code: 01 03 80 00 00 01 AD CA

Майдон	Тавсифи	Шарҳ
01	Суроғаи дастгоҳ	0x00 indicates the broadcast address, 0x01-0xFF indicates the device address
03	03 Фармон	Read the software version and device address
80 00	Software version register	0x4000: read the device address, 0x8000: read software version
00 01	Рақами байт	Собит 0x0001

AD CA

CRC16

The CRC16 checksum of the first 6 bytes of data

• Receive code: 01 03 02 01 2C B8 09

Майдон	Тавсифи	Шарҳ
01	Суроғаи дастгоҳ	0x00 indicates the broadcast address, 0x01-0xFF indicates the device address
03	03 Фармон	Read the software version and device address
02	Рақами байт	The number of bytes returned
01 2C	Версияи нармафзор	Converting to decimal and then shifting the decimal point two places to the left will represent the software version 0x012C = 300 = V3.00
B8 09	CRC16	The CRC16 checksum of the first 6 bytes of data

• Барои мисолampле:

Exception Function Code

• When the received command is incorrect or the device is abnormal, an exception response will be returned in the following format:
• Return code: 01 85 03 02 91

Майдон	Тавсифи	Шарҳ
01	Суроғаи дастгоҳ	0x00 indicates the broadcast address, 0x01-0xFF indicates the device address
85	Exception Function Code	Exception function code = Request function code + 0x80

03	Рақами байт	Кодекси истисно
02 91	CRC16	The CRC16 checksum of the first 6 bytes of data

• An exception code is a single-byte value that indicates the type of error. Several commonly used exception codes defined by the Modbus protocol:

Истисно Кодекс	Ном	Тавсифи
0х01	Функсияи ғайриқонунӣ	The requested function code is not supported
0х02	Суроғаи маълумоти ғайриқонунӣ	The requested data address is incorrect
0х03	Арзиши маълумоти ғайриқонунӣ	The requested data value or operation cannot be executed
0х04	Server Failure	Server equipment failure
0х05	Ҷавоб	The request has been received and is being processed
0х06	Device Busy	The device is currently busy and cannot perform the requested operation

• Захираҳо

Намоиш

• Намоиш

Нармафзор

• Sscom5.13.1_for_Modbus_RTU_Relay_32CH.zip
• Modbus Poll software
• SecureCRT software

Захираҳои марбут

• Modbus Protocol Specification
• Modbus Series BootLoader Description
• Protocol V1
• Using Modbus RTU Relay with Home Assistant

Саволҳо

Q: Can RS485 be directly connected to the Raspberry Pi's serial port?

A: No, it is not recommended as it may damage the device. Use an RS485 CAN HAT module for Raspberry Pi.

Q: What software is recommended for running demos?

A: For Raspberry Pi, use SSCOM Serial Port Debugging Assistant and Modbus Poll Software. For STM32, use Keil5 software. For Arduino, use Arduino IDE.

Ҳуҷҷатҳо / Сарчашмаҳо

Modbus RTU Relay 32CH Relay Module [pdf] Дастури дастур RTU Relay 32CH Relay Module, RTU Relay 32CH, Relay Module

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