Modbus RTU Relay 16CH
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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.
Introduction
This product is an industrial-grade RS485 interface controlled 8DI / 8DO digital isolated input-output module. It supports passive input/active input, utilizes Modbus RTU protocol, and includes built-in protection circuits such as power isolation, optocoupler isolation, self-resetting fuses, and TVS.
Hardware Test
RS485
- Connect the USB TO 485 and the target board with the cables, connect A --> A and B --> B, as shown below:
- Download Sscom5.13.1_for_Modbus_RTU_Relay_16CH and open it on the PC, open the corresponding port, and set the baud rate as 9600. Clicking on multiple strings opens multiple string-sending windows. Clicking on the corresponding function will send the corresponding command.
- If you need to send other commands, select "HEX" as the sending format and choose "Modbus CRC16" as the checksum. When entering the command, if the first six bytes are provided and you click on "Send," the CRC checksum will be automatically added.
- For detailed control commands, please check the development protocol.
Demo Test
Note: RS485 cannot be directly connected to the Raspberry Pi's serial port as it may damage the devices. It requires a level converter for RS485. It is recommended to use an RS485 CAN HAT module with the Raspberry Pi. For NUCLEO-F103RB and Arduino, it is recommended to use an RS485 CAN Shield module.
Raspberry Pi
Open the Raspberry Pi, and input the following commands to enter the configure interface:
sudo raspi-config Choose Interfacing Options -> Serial, disable shell visit, enable the hardware serial port
And then reboot the Raspberry Pi:
sudo reboot
Open /boot/config.txt file, and find the following configure sentence to enable the serial ports. If there is none, you can add it at the end of the file.
enable_uart=1
For Raspberry Pi 3B users, the serial port is for Bluetooth and needs to be removed.
#dtoverlay=pi3-miniuart-bt
And then reboot the Raspberry Pi:
sudo reboot
If you want to insert the RS485 CAN HAT into the Raspberry Pi, connect the A and B ports of the Modbus RTU Relay module and the RS485 CAN HAT module.
If you use other 485 devices, you need to make sure A-A and B-B.
Run the following commands:
sudo apt-get install unzip wget https://files.waveshare.com/upload/f/f0/Modbus_RTU_Relay_16CH_Code.zip unzip Modbus_RTU_Relay_16CH_Code.zip cd Modbus_RTU_Relay_16CH_Code/Python3 sudo python3 main.py
SRM32
The STM32 demos are based on the NUCLEO-F103RB and the RS485 CAN Shield module.
Find the STM32 program file directory and open the STM32 project. Note that before using the computer to ensure that the keil5 software has been installed, download the program to the development board can be downloaded.
Normal operation of the relay module will turn on and then turn off in turn. The serial port will output the command sent.
Arduino
The Arduino demos are based on the NUO PLUS and RS485 CAN Shield modules.
Use Arduino IDE to open the program, select the corresponding development board and then download the program.
The relay module will turn on and then turn off in order to run normally. The serial port will output the commands sent.
Development Protocol
Function Code Introduction
| Function Code | Note |
|---|---|
| 01 | Read relay status |
| 03 | Read the address and version |
| 05 | Write a single relay |
| 06 | Set baud rate and address |
| 0F | Write all relays |
Register address introduction
| Address (HEX) | Address storage content | Register value | Permission | Modbus function code |
|---|---|---|---|---|
| 0x0000 …… 0x000F |
1~6 channel relay address | 0xFF00: Relay on; 0x0000: Relay off; 0x5500: Relay flipped; |
Read/Write | 0x01,0x05,0x0F |
| 0x00FF | Operate all registers | 0xFF00: All relays are on; 0x0000: All relays are off; 0x5500: All relays are flipped; |
Write | 0x05 |
| 0x0200 …… 0x020F |
1~6 channel relay flash on | The delay time is data*100ms Value: 0x0007, delay: 7*100MS = 700MS |
Write | 0x05 |
| 0x0400 …… 0x040F |
1~6 channel relay flash off | The delay time is data*100ms Value: 0x0007, delay: 7*100MS = 700MS |
Write | 0x05 |
| 4x2000 | Serial port parameters | The upper eight bits are the check mode: 0x00~0x02 The lower eight bits are the baud rate mode: 0x00~0x07 |
Write | 0x06 |
| 4x4000 | Device address | Direct storage Modbus address Device address: 0x0001-0x00FF |
Read/write | 0x03,0x06 |
| 4x8000 | Software version | Convert to decimal and then move the decimal point two places to the left to indicate the software version 0x0064=100=V1.00 |
Read | 0x03 |
Single Relay Control
Sending Code: 01 05 00 00 FF 00 8C 3A
| Fields | Meaning | Remarks |
|---|---|---|
| 01 | Device Address | 0x00 is the broadcast address; 0x01-0xFF is the device address |
| 05 | 05 command | Control the relay command |
| 00 00 | Address | Control the register address of the relay, 0x00 - 0x000F |
| FF 00 | Command | 0xFF00: relay on 0x0000: relay off 0x5500: relay flip |
| 8C 3A | CRC16 | CRC16 checksum of the first 6 bytes of data |
Return code: 01 05 00 00 FF 00 8C 3A
| Field | Meaning | Remarks |
|---|---|---|
| 01 | Device Address | 0x00 is the broadcast address; 0x01-0xFF is the device address |
| 05 | 05 command | Control the relay commands |
| 00 00 | Address | Control the register address of the relay: 0x0000-0x000F |
| FF 00 | Command | 0xFF00: relay on 0x0000: relay off 0x5500: relay flip |
| 8C 3A | CRC16 | CRC16 checksum of the first 6 bytes of data |
For example:
[No. 1 address device]:
No. 0 relay on: 01 05 00 00 FF 00 8C 3A
No. 0 relay off: 01 05 00 00 00 00 CD CA
No. 1 relay on: 01 05 00 01 FF 00 DD FA
No. 1 relay off: 01 05 00 01 00 00 9C 0A
No. 2 relay on: 01 05 00 02 FF 00 2D FA
No. 2 relay off: 01 05 00 02 00 00 6C 0A
No. 3 relay on: 01 05 00 03 FF 00 7C 3A
No. 3 relay off: 01 05 00 03 00 00 3D CA
No. 0 relay flip: 01 05 00 00 55 00 F2 9A
No. 1 relay flip: 01 05 00 01 55 00 A3 5A
No. 2 relay flip: 01 05 00 02 55 00 53 5A
No. 3 relay flip: 01 05 00 03 55 00 02 9A
Control All Relays
Sending code: 01 05 00 FF FF 00 BC 0A
| Fields | Meaning | Note |
|---|---|---|
| 01 | Device Address | 0x00 is the broadcast address; 0x01-0xFF is the device address |
| 05 | 05 Command | Control relay commands |
| 00 FF | Address | Fixed 0x00FF |
| FF 00 | Command | 0xFF00: relay on 0x0000: relay off 0x5500: relay flip |
| BC 0A | CRC16 | CRC16 checksum of the first 6 bytes of data |
Return code: 01 05 00 FF FF 00 BC 0A
| Fields | Meaning | Code |
|---|---|---|
| 01 | Device Address | 0x00 is the broadcast address; 0x01-0xFF indicates the device address |
| 05 | 05 command | Control the relay commands |
| 00 FF | Address | Fixed 0x00FF |
| FF 00 | Commands | 0xFF00: relay on 0x0000: relay off 0x5500: relay flip |
| BC 0A | CRC16 | CRC16 checksum of the first 6 bytes of data |
For example:
[No. 1 address device]:
All relays on: 01 05 00 FF FF 00 BC 0A
All relays off: 01 05 00 FF 00 00 FD FA
All relays flip: 01 05 00 FF 55 00 C2 AA
Read the Relay Status
Sending code: 01 01 00 00 00 10 3D C6
| Fields | Meaning | Note |
|---|---|---|
| 01 | Device Address | 0x00 is the broadcast address; 0x01-0xFF indicates the device address |
| 01 | 01 Command | Query Relay Status Command |
| 00 00 | Relay Start Address | Fixed 0x0000 |
| 00 10 | Relay Numbers | Fixed 0x0010 |
| 3D C6 | CRC16 | CRC16 checksum of the first 6 bytes of data |
Return code: 01 01 02 00 00 B9 FC
| Field | Meaning | Note |
|---|---|---|
| 01 | Device Address | 0x00 is the broadcast address, 0x01-0xFF is the device address |
| 01 | 01 Command | Query Relay Status Command |
| 02 | Number of bytes | Returns all bytes of the status information |
| 00 00 | Status of the query | Returned relay status Bit0: the first relay status; Bit1: the second relay status; Bit2: the third relay status; …… Bit15: the 16th relay status. |
| B9 FC | CRC16 | CRC16 checksum of the first 6 bytes of data |
For example:
[NO.1 address device]
Send: 01 01 00 00 00 08 3D CC
Return: 01 01 02 00 00 B9 FC //All relays off
Send: 01 01 00 00 00 08 3D CC
Return: 01 01 02 00 01 78 3C //Relay 0 is on, the rest of the relays are off.
Send: 01 01 00 00 00 08 3D CC
Return: 01 01 02 00 41 79 CC //Relays 0 and 6 are on, the rest are off
Write Relay Status
Sending code: 01 0F 00 00 00 10 02 FF FF E3 90
| Field | Meaning | Note |
|---|---|---|
| 01 | Device address | 0x00 is the broadcast address; 0x01-0xFF is the device address |
| 0F | 0F Command | Write relay status command |
| 00 00 | Relay start address | Fixed 0x0000 |
| 00 10 | Relay numbers | Fixed 0x0010 |
| 02 | Byte count | Fixed 0x02 |
| FF FF | Relay status | Bit0: control the first relay; Bit1: control the second relay; Bit2: control the third relay; …… Bit15: control the 16th relay |
| E3 90 | CRC16 | CRC16 checksum of the first 6 bytes of data |
Return code: 01 0F 00 00 00 10 54 07
| Field | Meaning | Note |
|---|---|---|
| 01 | Device Address | 0x00 is the broadcast address; 0x01-0xFF is the device address |
| 0F | 0F command | All register control commands |
| 00 00 | Relay start address | Fixed 0x0000 |
| 00 10 | Relay numbers | Fixed 0x0010 |
| 54 07 | CRC16 | CRC16 checksum of the first 6 bytes of data |
For example:
[No.1 address device]
All relays on: 01 0F 00 00 00 10 02 FF FF E3 90
All relays off: 01 0F 00 00 00 10 02 00 00 E2 20
0-1 ON; 3-15 OFF: 01 0F 00 00 00 10 02 00 03 A2 21
Relay Flash On and Flash Off Command
Sending code: 01 05 02 00 00 07 8D B0
| Field | Meaning | Note |
|---|---|---|
| 01 | Device Address | 0x00 is the broadcast address, 0x01-0xFF is the device address |
| 05 | 05 Command | Single control demmand |
| 02 | Command | 02 is the command for flashing on, 04 is the command for flashing off |
| 00 | Relay Address | The address of the relay to be controlled: 0x00~0x0F |
| 00 07 | Interval time | Delay time for data *100ms Value: 0x0007, Delay: 7*100MS=700MS |
| 8D B0 | CRC16 | CRC16 checksum of the first 6 bytes of data |
Return code: 01 05 02 00 00 07 8D B0
| Field | Meaning | Note |
|---|---|---|
| 01 | Device Address | 0x00 is the broadcast address; 0x01-0xFF is the device adress |
| 05 | 05 Command | Single control command |
| 02 | Command | 02 is the command for flashing on, 04 is the command for flashing off |
| 00 | Relay Address | The address of the relay to be controlled: 0x00~0x0F |
| 00 07 | Interval time | Delay time for data*100ms Value: 0x0007, delay: 7*100MS=700MS |
| 8D B0 | CRC16 | CRC16 checksum of the first 6 bytes of data |
Note:
The maximum setting for the flash on/flash off time is 0x7FFF.
For example:
[No.1 address device]
Relay 0 flashes on: 01 05 02 00 00 07 8D B0 //700MS=7*100MS=700MS
Relay 1 flashes on: 01 05 02 01 00 08 9C 74 //800MS
Relay 0 flashes off: 01 05 04 00 00 05 0C F9 //500MS
Relay 1 flashes off: 01 05 04 01 00 06 1D 38 //600MS
Set the Baudrate Command
Sending code: 00 06 20 00 00 05 43 D8
| Field | Meaning | Note |
|---|---|---|
| 00 | Device Address | 0x00 is the broadcast address, 0x01-0xFF is the device address |
| 06 | 06 Command | Set the baud rate and the device address |
| 20 00 | Command Register | 0x2000 is the configurable baudrate, 0x4000 sets the device address |
| 00 | Checksum Method | 0x00: no checksum, 0x01: even parity, and 0x02: odd parity |
| 05 | Baudrate value | The baud value corrsponding to 0x00: 4800 0x01: 9600 0x02: 19200 0x03: 38400 0x04: 57600 0x05: 115200 0x06: 128000 0x07: 256000 |
| 43 D8 | CRC16 | CRC16 checksum of the first 6 bytes of data |
Return code: 00 06 20 00 00 05 43 D8
| Field | Meaning | Note |
|---|---|---|
| 00 | Device address | 0x00 is the broadcast address; 0x01-0xFF is the device address |
| 06 | 06 Command | Set the baudrate and the device address |
| 20 00 | Command Register | 0x2000 is the configurable baudrate, 0x4000 sets the device address |
| 00 | Checksum Method | 0x00 is no checksum, 0x01 is odd check, 0x02 is even check |
| 05 | Baudrate | The baud value corrsponding to 0x00: 4800 0x01: 9600 0x02: 19200 0x03: 38400 0x04: 57600 0x05: 115200 0x06 : 128000 0x07: 256000 |
| 43 D8 | CRC16 | CRC16 checksum of the first 6 bytes of data |
For example:
[No.1 address device]
Set the baudrate 4800: 00 06 20 00 00 00 83 DB
Set the baudrate 9600: 00 06 20 00 00 01 42 1B
Set the baudrate 115200: 00 06 20 00 00 05 43 D8
Set the Device Address Comand
Sending code: 00 06 40 00 00 01 5C 1B
| Field | Meaning | Note |
|---|---|---|
| 00 | Device Address | 0x00 is the broadcast address, 0x01-0xFF is the device address |
| 06 | 06 Command | Configurable baudrate and device address |
| 40 00 | Command Register | 0x2000 is for setting the baudrate, and 0x4000 is for setting the device address |
| 00 01 | Device address | Set the device address, 0x0001-0x00FF |
| 5C 1B | CRC16 | CRC16 checksum of the first 6 bytes of data |
Return code: 00 06 40 00 00 01 5C 1B
| Field | Meaning | Note |
|---|---|---|
| 00 | Device Address | 0x00 is the broadcast address, 0x01-0xFF is the device address |
| 06 | 06 Command | Set the baudrate and the device address |
| 40 00 | Command Register | 0x2000 is for setting the baudrate, 0x4000 is for setting the device address |
| 00 01 | Device address | Set the device address, 0x0001-0x00FF |
| 5C 1B | CRC16 | CRC16 checksum of the first 6 bytes of data |
For example:
[No.1 address device]
Set the device address as 0x01: 00 06 40 00 00 01 5C 1b
Set the device address as 0x02: 00 06 40 00 00 02 1C 1A
Set the device address as 0x03: 00 06 40 00 00 03 DD DA
Read the Device Address Command
Sending code: 00 03 40 00 00 01 90 1B
| Field | Meaning | Note |
|---|---|---|
| 00 | Device address | 0x00 is the broadcast address; 0x01-0xFF is the device address |
| 03 | 03 Command | Read the device address command |
| 40 00 | Command register | 0x4000 is to read the device address, 0x8000 is to read the software version |
| 00 01 | Bytes number | Fixed 0x0001 |
| 90 1B | CRC16 | CRC16 checksum of the first 6 bytes of data |
Return code: 01 03 02 00 01 79 84
| Field | Meaning | Note |
|---|---|---|
| 00 | Device address | 0x00 indicates the broadcast address; 0x01-0xFF indicates the device address |
| 03 | 03 command | Read software version, read device address command |
| 02 | Byte number | Return the number of bytes |
| 00 01 | Device address | Set device address, 0x0001-0x00FF |
| 79 84 | CRC16 | CRC16 checksum of the first 6 bytes of data |
For example:
[NO.1 address device]
Sending: 00 03 40 00 00 01 90 1B
Return: 01 03 02 00 01 79 84 //Address 0x01
[NO.2 address device]
Sending: 00 03 40 00 00 01 90 1B
Return: 02 03 02 00 02 7D 85 //Address 0x02
[NO.3 address device]
Sending: 00 03 40 00 00 01 90 1B
Return: 03 03 02 00 03 81 85 //Address: 0x03
Read Software Version Command
Sending code: 00 03 80 00 00 01 AC 1B
| Field | Meaning | Note |
|---|---|---|
| 01 | Device Address | 0x00 indicates the broadcast address; 0x01-0xFF indicates the device address |
| 03 | 03 Command | Read software version, read device address command |
| 80 00 | Command Register | 0x4000 is to read the device address, 0x8000 is to read the software version |
| 00 01 | Byte Number | Fixed 0x0001 |
| 8F CA | CRC16 | CRC16 checksum of the first 6 bytes of data |
Return code: 01 03 02 00 64 B9 AF
| Field | Meaning | Note |
|---|---|---|
| 01 | Device Address | 0x00 indicates the broadcast address; 0x01-0xFF indicates the device address |
| 03 | 03 Command | Read the software version and the device address commands |
| 02 | Byte Number | Return code |
| 00 64 | Software Version | Convert to decimal and move the decimal point two places to the left to indicate the software version 0x0064=100=V1.00 |
| B9 AF | CRC16 | CRC16 checksum of the first 6 bytes of data |
For example:
Sending: 00 03 80 00 00 01 AC 1B
Return: 01 03 02 00 64 B9 AF //0x0064 = 100 =V1.00
Resource
Demo
Software
Related application
FAQ
Yes, it also supports Win7/8/8.1/10/11, Mac, Linux, Android, and WinC...
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Remove the 120-ohm termination matching resistor for RS485.
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- Support USB to RS232, RS485 or TTL;
- Does not support RS232, RS485, TTL simultaneous conversion to USB
- RS232, RS485 and TTL cannot be converted to each other
Not supported, RS232, RS485 and TTL can not be interchangeable, support USB to RS232, RS485, or TTL.
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TTL and RS232 are full-duplex communication, you can short RXD and TXD to test, RS485 is half-duplex communication, you can test with an external USB to RS485 device, the following figure is the loopback test TTL:
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VCC is the power supply pin, which can be switched by 5V or 3.3V (50mA) to power the connected device, if the device already has another external power supply, it can be connected without VCC.
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- The module is only for interface switch in terms of hardware, it does not support Modbus. It supports connecting to Modbus devices with an onboard RS485 (RS232, TTL) interface.
- When learning the Modbus protocol, you need to understand Modbus's function code and data format. Modbus has a variety of function codes, each of which corresponds to one type of operation, such as reading the coil status, reading the input status, reading the holding register, and so on.
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No, but it is more stable with a connection to GND. For better performance, reliability, and anti-interference, it is recommended to connecting to GND for a long-distance communication.
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1、If the module does not respond to the command, verify that the baud rate and device ID are correct. You may also try Restoring the factory settings.
2、If the above steps do not resolve the issue, please submit a ticket to contact the Waveshare technical support team.
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It is about 3.7W, please refer to the figure below:
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5V 0.8A.
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Support
Technical Support
If you need technical support or have any feedback/review, please click the Submit Now button to submit a ticket, Our support team will check and reply to you within 1 to 2 working days. Please be patient as we make every effort to help you to resolve the issue.
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