Modbus POE ETH Relay

RS485

Overview

Hardware Description

Hardware Connection

Connects Modbus POE ETH Relay to the LAN via a network cable, powered through the power port or via POE.

Note: The above picture is using a PoE port for power supply. If the network cable you used is a normal one, you need to connect an external power adapter to supply power in the range of 7~36V.

Electrical Safety Precautions

This product must be operated and used by professional electricians or technical personnel. During use, please ensure electrical safety and take measures to prevent leakage and insulation.

Before installing, maintaining, or replacing relay equipment, be sure to turn off the power and unplug the plug.

Do not attempt to disassemble relay equipment to avoid damaging the equipment or causing the risk of electric shock.

Please install and place the relay equipment product properly. Do not use it in damp, overheated, or flammable environments to avoid safety incidents caused by improper installation or use.

Indicator Note

Indicator	Status Description
RUN	Ethernet operation indicator. After the chip is working properly, it will output a square wave with a period of 2 seconds.
STA	MCU indicator, blinking when the MCU is operating normally.
TXD	Send indicator, light is on when sending data.
RXD	Receive indicator, light is on when receiving data.
Ethernet Port Green Light	The green light is on when a TCP connection is established and can be used to determine if the module has established a communication link with the host computer software.
Ethernet Port Yellow Light	Data transmission light, when there is data transmission on the network port, the yellow light transition state will change, which can be used to determine whether there is data transmission.

Software Installation

Vircom can be used for configuring device IP and other parameters, as well as creating virtual serial ports. If the virtual serial port functionality is not needed, you can simply download the installation-free version of the configuration software.

VirCom: Configuration Software
Virtual serial port: Serial port driver
Sscom5.13.1_for_Modbus_POE_ETH_Relay: Sscom software

Driver installation requires decompression, double-click the software to install, if the virtual serial port in Vircom is not displayed, then reboot and check again.

Example

TCP Communication Test

Software Preparation

VirCom: Configuration Software
Sscom5.13.1_for_Modbus_POE_ETH_Relay: Sscom software

Host Computer Setting

After connecting to the Modbus POE ETH Relay, connect it to the network. Run the Vircom software, (The computer on which Vircom is installed must be on the same LAN as the module.).
The operation is shown below:

① Click Device
② Click Auto Search
③ Software search recognizes Modbus POE ETH Relay devices connected to the LAN.
④ Select the device, and then click Edit Device or directly double click the searched device.
⑤ Set up the device parameters.
- Click the "Local IP" button to identify the computer's IP address, change the "IP Address" to a static address, and note that the static IP address entered is not used by other devices and needs to be on the same LAN as the computer.
- The operating mode is TCP server. The serial port setting defaults to 115200 and cannot be modified.
- The "Convert Protocol" in the Advanced settings, the default setting is "None", that is, you select modbus rtu protocol. If you use Modbus_TCP protocol, you can select "modbus tcp protocol".
⑥ After setting, click Modify Setting.
⑦ Click Restart Dev. After restarting the module, the new setting takes effect.

As shown below:

The last step is to click "Modify Settings" to save the settings and take effect.

TCP Communication Test

Open the serial debugging assistant window, select TCPClient for the port number, modify the remote IP and port number according to the above Vircom settings, click the "Connect" button to connect to the TCP server, the green light of the network port will light up after successful connection.

Clicking on multiple strings will open multiple string-sending windows, and clicking on the corresponding functions will send the corresponding commands.
Please refer to the development agreement for detailed Development Protocol.

Virtual Serial Port Testing

The SSCOM2 in the diagram communicates directly with the TCP and serial port server. In order to allow users to communicate with the serial port server using their existing serial port software, a virtual serial port needs to be added between the user program and the serial port server. As shown in the diagram, Vircom and the user program run on the same computer. Vircom virtualizes a COM port that corresponds to the serial port server. When the user program opens the COM communication, it can send data to the user's serial port device through the Vircom serial port server. The following steps demonstrate this operation:
Click on "Serial Port Management" on the Vircom main interface.

Click on "Add" and select to add COM2. Note that COM5 is a COM port that does not exist on the computer originally.
After that, go to the device management and double-click on the device that needs to be bound to COM2. As shown in the diagram, select COM2 from the "Virtual Serial Port" list in the top left corner. Then click on "Modify Settings" and then click on "Restart Device".

Return to the main Vircom interface. You can see that COM2 is already connected to the device with IP 192.168.1.200. At this point, you can use COM2 to communicate instead of SSCOM2.

Open it on your computer, open the corresponding port number, set the baud rate to 115200, click Multi-String to open the Multi-String Send window, and click the corresponding function to send the corresponding command.

MODBUS TCP Test

By default, data is transparently transmitted using the Modbus RTU protocol. If you need to implement Modbus TCP to RTU conversion, you need to select the conversion protocol as "Modbus TCP Protocol" in the device settings dialog, as shown in the diagram below. In this case, the device port automatically changes to 502. Users can connect their Modbus TCP tool to the IP of the serial port server on port 502, and the Modbus TCP commands they send will be converted to RTU commands and outputted through the serial port.

For example, if the server's Ethernet port receives a Modbus TCP command of 00 00 00 00 00 06 01 05 00 00 FF 00 (to turn on the first relay), the host controller will receive the Modbus RTU command of 01 05 00 00 FF 00 8C 3A.

Click on "More advanced options..." Select the Modbus gateway type as a non-storage Modbus gateway.

Note: The default Modbus gateway type is storage type, which will automatically send query commands several times, which may cause the master chip not to respond, and the query commands will not be affected. Therefore, you need to set it as Multi-host non-storage type.

Open the Sscom software, click on the Import ini button in the Multiple String Sender column, and select the Modbus tcp.ini file to import.

If the error "A component named HEX0 already exists" is displayed, close the software and reopen it. Then close the software and reopen it, then re-import the file.

After successful import, the following is displayed, click on the corresponding function to send the corresponding command.

Please refer to the Modbus TCP protocol section later for more details on Modbus TCP conversion.

WEB Configuration

Using Vircom, you can search and configure device parameters in different network segments. For Web configuration, you must first ensure that the computer and the serial server are in the same IP segment, and you need to know the IP address of the serial server in advance. But web configuration can be done on any computer without Vircom.
1. Enter the IP address of the serial server in the browser, such as http://192.168.1.200

2. Enter password in "Password": There is no login password set by default in the factory, you can enter a password at will, and click the Login button to log in. After setting the password to log in, the settings at "Modify webpage login password" will take effect:

3. The serial server parameters can be modified on the web page that appears. For the relevant parameters, please refer to Table 4 for the meaning of the parameters.
4. After modifying the parameters, click the "Submit" button.
5. If the configuration web page files are overwritten during the configuration and downloading of MQTT and Jetson Modbus firmware, causing the configuration web page to be inaccessible, please follow these steps to re-download the web page files:

Configuration Interface Web Files to Modbus POE ETH Relay.

For more details, please refer to Ethernet Module User Manual

Demo Example

Raspberry Pi

Connect the Raspberry Pi and the ModBus POE ETHG Relay module to the same LAN.
Open the Raspberry Pi terminal and run the program by entering the following command.

sudo apt-get install unzip
wget https://files.waveshare.com/upload/e/e0/Modbus_POE_ETH_Relay_Code.zip
unzip Modbus_POE_ETH_Relay_Code.zip
cd Modbus_POE_ETH_Relay_Code

#modbus rtu protocol
vi modbus_rtu.py  #Change the IP address and port number according to the actual situation
sudo python3 modbus_rtu.py

#modbus tcp protocol
vi modbus_tcp.py  #Change the IP address and port number according to the actual situation
sudo python3 modbus_tcp.py

Note: To run this demo, you need to modify the demo file to change the IP address and port number to the actual IP address and port number of the ModBus POE ETHG Relay.

Modbus RTU 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

Single Relay Control

Sending Code: 01 05 00 00 FF 00 8C 3A

Fields	Meaning	Remarks
01	Device Address	Fixed 0x01
05	05 Command	Control the relay command
00 00	Address	Control the register address of the relay, 0x00 - 0x0008
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	Fixed 0x01
05	05 Command	Control the relay commands
00 00	Address	Control the register address of the relay: 0x0000-0x0008
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:

CH1 relay on: 01 05 00 00 FF 00 8C 3A
CH1 relay off: 01 05 00 00 00 00 CD CA
CH2 relay on: 01 05 00 01 FF 00 DD FA
CH2 relay off: 01 05 00 01 00 00 9C 0A
CH3 relay on: 01 05 00 02 FF 00 2D FA
CH3 relay off: 01 05 00 02 00 00 6C 0A
CH4 relay on: 01 05 00 03 FF 00 7C 3A
CH4 relay off: 01 05 00 03 00 00 3D CA
CH1 relay flip: 01 05 00 00 55 00 F2 9A
CH2 relay flip: 01 05 00 01 55 00 A3 5A
CH3 relay flip: 01 05 00 02 55 00 53 5A
CH4 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	Fixed 0x01
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	Fixed 0x01
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 08 3D CC

Fields	Meaning	Note
01	Device address	Fixed 0x01
01	01 command	Query Relay Status Command
00 00	Relay start address	Fixed 0x0000
00 08	Relay numbers	Fixed 0x0008
3D C6	CRC16	CRC16 checksum of the first 6 bytes of data

Return code: 01 01 01 00 51 88

Field	Meaning	Note
01	Device address	Fixed 0x01
01	01 command	Query Relay Status Command
01	Number of bytes	Returns all bytes of the status information
00	Status of the query	Returned relay status Bit0: the first relay status; Bit1: the second relay status; Bit2: the third relay status; …… Bit7: the 8th relay status.
51 88	CRC16	CRC16 checksum of the first 6 bytes of data

For example:

Send: 01 01 00 00 00 08 3D CC
Return: 01 01 01 00 51 88 //All relays off
Send: 01 01 00 00 00 08 3D CC
Return: 01 01 01 01 90 48 //CH1 Relay is on, the rest of the relays are off.
Send: 01 01 00 00 00 08 3D CC
Return: 01 01 01 41 91 B8 //CH1 Relays and CH7 are on, the rest are off

Write Relay Status

Sending code: 01 0F 00 00 00 08 01 FF BE D5

Field	Meaning	Note
01	Device Address	Fixed 0x01
0F	0F Command	Write relay status command
00 00	Relay Start Address	Fixed 0x0000
00 08	Relay Numbers	Fixed 0x0008
01	Byte Count	Fixed 0x01
FF	Relay status	Bit0: control the first relay; Bit1: control the second relay; Bit2: control the third relay; …… Bit7: control the 8th relay
BE D5	CRC16	CRC16 checksum of the first 6 bytes of data

Return code: 01 0F 00 00 00 01 94 0B

Field	Meaning	Note
01	Device Address	Fixed 0x01
0F	0F Command	All register control commands
00 00	Address	Fixed 0x0000
00 08	Relay Numbers	Fixed 0x0008
54 0D	CRC16	CRC16 checksum of the first 6 bytes of data

For example:

[No.1 address device]

All relays on: 01 0F 00 00 00 08 01 FF BE D5
All relays off: 01 0F 00 00 00 08 01 00 FE 95
CH1-2 ON; 4-8 OFF: 01 0F 00 00 00 08 01 03 BE 94

Relay Flash On and Flash Off Command

Sending code: 01 05 02 00 00 07 8D B0

Field	Meaning	Note
01	Device Address	Fixed 0x01
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: 0x00~0x08
00 07	Interval Time	Delay time for data 100ms Value: 0x0007, Delay: 7100MS = 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	Fixed 0x01
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: 0x00~0x08
00 07	Interval Time	Delay time for data100ms Value: 0x0007, delay: 7100MS = 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]

CH1 Relay flashes on: 01 05 02 00 00 07 8D B0 //700MS = 7*100MS = 700MS
CH2 Relay flashes on: 01 05 02 01 00 08 9C 74 //800MS
CH1 Relay flashes off: 01 05 04 00 00 05 0C F9 //500MS
CH2 Relay flashes off: 01 05 04 01 00 06 1D 38 //600MS

Read the Device Address Command

Sending code: 00 03 40 00 00 01 90 1B

Field	Meaning	Note
00	Device Address	Fixed 0x01
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	Fixed 0x01
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, fixed 0x01
79 84	CRC16	CRC16 checksum of the first 6 bytes of data

For example:

Sending: 00 03 40 00 00 01 90 1B
Return: 01 03 02 00 01 79 84 //address 0x01

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

Modbus TCP Development Protocol

Here is a brief introduction to Modbus TCP and Modbus RTU protocol conversion using the above commands to open the first relay as an example.

Modbus RTU command: 01 05 00 00 FF 00 8C 3A

Field	Meaning	Note
01	Device Address	Fixed 0x01
05	05 Command	Control relay commands
00 00	Address	Address of the register to control the relay, 0x00, that is, the first relay
FF 00	Command	0xFF00: Relay on
8C 3A	CRC16	CRC16 checksum of the first 6 bytes of data

Modbus TCP command: 00 00 00 00 00 06 01 05 00 00 FF 00

Field	Meaning	Note
00 00	Message Label	Both be 0x00
00 00	Modbus Label	Must both be 0, which means this is Modbus communication
00 06	Byte Length	Indicates the number of all bytes that follow, followed by 6 bytes
01	Device Address	Fixed 0x01
05	05 Command	Control relay commands
00 00	Address	Address of the register to control the relay, 0x00, i.e. the first relay
FF 00	Command	0xFF00: relay on

By comparing the commands above, we can observe that to convert a Modbus RTU command to Modbus TCP protocol, the CRC check is removed, and the command is prefixed with five 0x00 bytes followed by a byte representing the length.

Advanced Applications - MQTT Connected Cloud Platform

How to Connect Modbus POE ETH Relay to Waveshare Cloud

Software Preparation

Hardware Preparation

Modbus POE ETH Relay

How to Connect

Sign up for Waveshare Cloud

Create an account access the platform using an email verification code, and then enter "Devices | Attributes" to create the device to operate after login.

Viewing the device list, a new device appears:

In the device menu, click to display the attributes section. Then, click on the "Address" button on the right to view the MQTT connection parameters. These parameters are preconfigured as part of the one-click setup, and the relevant attributes have already been created.

The creation of the Waveshare Cloud device is now complete.

Configure Modbus POE ETH Relay with Vircom Software

Plug in the device, connect it to the Ethernet cable, ensuring that the computer and the device are on the same local network, and then open Vircom to follow the instructions as shown in the diagram.

Fill in the corresponding boxes with the parameters provided by Waveshare Cloud. Please note that errors may occur at this stage, and there may be related configuration files in the target directory. In this case, it is advisable to create a new empty directory and point to this empty directory.

Confirm and then download the config.

Afterward, click the "Refresh" button to search for the device. The device will automatically restart after updating the settings. At this point, you should see that the TCP Connection status is now 'Established.'

Return to Waveshare Cloud to check the device status, which should now be in the "online" state.

Access to the device is now complete.

Device Control

Dashboard Control

Enter the Dashboard interface and select the corresponding device to develop.

Controls the corresponding access switch buttons to perform operations:

Debug Online Test

Resource

Demo

Demo code

Software

Vircom
Serial port driver: Virtual serial port
SSCOM software: Sscom5.13.1 for Modbus POE ETH Relay

Related application

Using Modbus RTU Relay with Homeassistant

FAQ

Question:I sent a command to control the relay, but it didn’t respond. What could be the issue??

Answer:

The command must be sent in hex format with a CRC checksum.

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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Question:I have forgotten the parameters set by Vircom for the network port. How to restore the factory settings?

Answer:

*It is necessary to disassemble the shell and use tweezers to short-circuit the pad under the DEF silk screen for more than 5 seconds. The module will be reset to the IP of 192.168.1.254.

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Question:What is the default IP configuration on the POE Modbus ETH Relay board?

Answer:

The default IP is 192.168.1.200.
If you restore it to factory mode, the IP will be set to 192.168.1.254.

{{{5}}}

Question:What is the operation temperature?

Answer:

-15℃~70℃.

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Question:What is the minimum wattage required for the 24964 relay board?

Answer:

The minimum required voltage is 7V. By the way, the power consumption is 0.2W when no-load and about 4W when the relay is fully open.

{{{5}}}

Support

Technical Support

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