How to Achieve Modbus RTU to/over TCP between Linovision LoRaWAN Gateways and Controllers

Andy Chen


Modbus RTU bridge LoRaWAN is a feature which can set up Modbus-LoRaWAN data transmission between Linovision controllers and Modbus TCP/TCP clients via  Linovision LoRaWAN gateways. The basic procedures are as follows:

  1. Send Modbus TCP/RTU reading or writing commands from a TCP client or Modbus TCP client
  2.  Linovision gateways receive commands and translate them to Modbus RTU commands, then forward to  Linovision controllers via LoRaWAN
  3.  Linovision controllers receive and response the commands and return the results
  4.  Linovision gateways receive the results and send to TCP client directly or translate to Modbus TCP results and send to Modbus TCP client


  • Linovision Controllers: IOT-C501
  • IOT-G6x LoRaWAN Gateways 
  • Toolbox Software
  • NetAssit (TCP Client simulate tool or Modbus Doctor (Modbus TCP client simulate tool)
  • Modbus Slave or other Modbus RTU devices (meters, sensors, etc.)



1. Linovision Controller Configuration

2. Linovision Gateway Configuration

3. TCP Client/Modbus TCP Configuration

3.1 TCP Client Configuration

3.2 Modbus TCP Configuration

4. Test

4.1 Transmission between Controllers and RS485 Devices

4.2 Send Query from Gateway

4.3 Send Query from TCP Client

4.4 Read to Modbus TCP

4.5 Write from Modbus TCP


1. Linovision Controller Configuration

Before powering on Linovision controllers, please connect your Modbus RTU devices to RS485 port of controllers.

With Linovision controllers connected to PC with USB cable, open Toolbox. Select the USB port and type login password. The default password is 123456.

Navigate to General > RS485 page, enable Modbus RS485 bridge LoRaWAN and configure the port which is specified for bridging. In this example we use 200 as Modbus RS485 bridge LoRaWAN port.




Navigate to LoRaWAN page and select the working mode as Class C. You could also find essential attributes of the controllers and you would need them to register it onto Linovision gateways.



2. Linovision Gateway Configuration

Connect Linovision controllers to gateway following article How to Connect LoRaWAN Node/Sensor to Linovision Gateway. When registering devices in Network Server->Device page, select Modbus RTU Data transmission mode as required and type necessary information. If you connect TCP client to gateway and send Modbus RTU commands, select Modbus RTU over TCP; if you connect Modbus TCP client to gateway and send Modbus TCP commands, select Modbus RTU to TCP.

NOTE: Please type the Fport as Modbus RS485 bridge LoRaWAN port (In this example Fport is 200). TCP Port is used for allowing TCP client or Modbus TCP master connection.

3. TCP Client/Modbus TCP Configuration

3.1 TCP Client Configuration

Open NetAssist on PC, type in IP address of gateway as IP address of TCP server, Server Port should be the same as the TCP Port in gateway. Click Connect to connect the client to gateway.


3.2 Modbus TCP Configuration

Open Modbus Doctor on PC, type in IP address of gateway as IP address of Modbus TCP server, NumPort should be the same as the TCP Port in gateway. Click CLOSE, choose CONNECTION.





4. Test

Modbus over/to TCP share the same topology, except that the protocol in TCP client side is different. Testing Modbus over TCP is using original Modbus and TCP/IP. While testing Modbus to TCP we introduce Modbus TCP/IP (also Modbus-TCP) which is simply the Modbus RTU protocol with a TCP interface that runs on Ethernet.


4.1 Transmission between Controllers and RS485 Devices

Connect controller RS485 port to PC and stimulate serial data with Modbus Slave.

In Toolbox, configure a Modbus channel to poll data from Modbus Slave tool. If you can read data, the communication is on.




4.2 Send Query from Gateway

Use the following Modbus example to test the communication between gateway and controller.

Query frame:


Slave ID Function Address Length Parity
0x01 0x03 0x00 0x00 0x00 0x02 0xC4 0x0B


Response frame:

Slave ID Function Length Data Parity
0x01 0x03 0x04 0x00 0x01 0x00 0x02 0x2A 0x32


Go to Network Server > Packets page, put in controller Device EUI and Port 200, select type as hex, then click Send to send Modbus command to controller.



A: gateway sends Modbus downlink successfully

B: Reply from controllers

C: ACK package from controllers


The details of reply packet is shown below:


4.3 Send Query from TCP Client

Send Modbus RTU format command 010300000002c40b to read first two digit of data, gateway (TCP server) will respond the Modbus reply 010304000100022A32.

In web GUI of gateway, you can check the details that sending the message from TCP client and receiving the replies from controllers.



Click the exclamation mark to see packets details, payload in hex matches what TCP client receives and is correctly “1,2”.


4.4 Read to Modbus TCP

Enable SPY MODE and click CONNECTION, see it’s printed in status:

Status: Connecting to

Status: Connected


As Modbus Slave has 10 addresses for default so we set Length as 10 too, click READING. You can see the query frame in darker blue and response frame in lighter one in the traffic communication block on the right.



Here is a data table of Modbus TCP communication protocol.


Query Frame Response Frame
Byte Content Byte Content
0-4 Start 0-4 Start
5 Whole Length 5 Whole Length
6 Slave ID 6 Slave ID
7 Function Code 7 Function Code
8, 9 Start Address 8 Data Length
9, 10 Data
10, 11 Address Length 11, 12 Data
... Data


According to the table we can tell the data read from Modbus RTU is 1,2 which is correct. In web GUI of gateway, you can check the details that sending the message from TCP client and receiving the replies from controllers.



4.5 Write from Modbus TCP

Modbus Doctor supports writing to Modbus RTU. You can input random number in Value of each Register, click WRITING. You can read the communication traffic according to the table above.



In Modbus Slave, you can see the value has changed correspondingly.

Read more →

How to Connect LoRaWAN Nodes to Linovision Gateway

Andy Chen


Linovision IoT gateway has built-in network server. When network server is enable, users can add LoRAWAN nodes/sensors to gateway and check the data directly. This article will guide you how to connect LoRaWAN nodes/sensors to Linovision Gateway.


  • Linovision LoRaWAN Gateway IOT-G6x or G8x.
  • LoRaWAN Node/Sensor (take Linovision IOT-S500TH as example).

Make sure sensor and gateway support the same LoRa frequency such as US915.


1. Before configuration, make sure the LoRaWAN node/sensor is not activated in other network servers. Take IOT-S500-TH as example, run Linovision Toolbox App on smart phone via NFC or open Toolbox on PC via USB Type-C to makes sure Join Status of the sensor is De-Activate.



2. Go to Packet Forwarder -> General to enable localhost server.

Click Save & Apply.


3. Go to Network Server -> General to enable built-in Network Server.

Click Save & Apply.


4. Go to Network Server -> Applications to add application.

Name & Description: user-defined.


5. Go to Network Server -> Profiles to add a profile.

Name: user-defined.

Join Type & Class Type: same as the ones on the sensor.


6. Go to Network Server -> Deviceto add sensors.

Device Name & Description: user-defined.

Device EUI: the Device EUI of the sensor. For Linovision sensors, you can find it on the label or  ToolBox.

Device-Profile & Applications: the ones you added in the above steps.

Application Key (AppKey): the application key of the sensor. For Linovision sensors, it’s a general one (5572404c696e6b4c6f52613230313823). You can also find it on user guide.


If Join Type is ABP, please fill in  below parameters:

Device Address: the 5th to 12th digits of SN of sensor.

Network Session Key (NwkSKey)/Appcation Session Key (AppSKey): for Linovision sensors, it’s a general one (5572404C696E6B4C6F52613230313823). You can also find it on user guide.

Click Save & Apply.


7. After the sensor joins the gateway successfully, you can see it’s Activated.


Go to Network Server -> Packets of Linovision Gateway to check uplink data that sensor reports.


You can also see Join Status is Activate from corresponding software.


Read more →

RS485 Modbus 7-in-1 Ultrasonic Weather Station

Andy Chen

IOT-S300WS7 is an ultimate all-in-one RS485 Modbus weather monitoring system for various and continuous atmospheric conditions including air temperature, relative humidity, barometric pressure, light intensity, rainfall(optical), wind speed, and wind direction (ultrasonic). It boasts high resolution and accuracy with rugged and aesthetic housing.

Outstanding Features

  • All-in-One Weather Station - This weather monitoring system is designed to monitor various and continuous atmospheric conditions, including air temperature, relative humidity, barometric pressure, light intensity, precipitation intensity, wind speed, and wind direction.
  • RS485 Compatibility - The output signal is RS485, the standard Modbus-RTU communication protocol, which supports changing the communication address and wave special rate and other functions. And RS485 support as far as 1200 meters communication. while supports secondary development and is widely used.
  • Ultrasonic Sensor - For precise measurement, the sensors to measure wind speed and wind direction use ultrasound instead of traditional mechanical 3-cup or vane anemometer.
  • Greater Stability - Radiation shields are equipped to ensure accurate ambient measurement.
  • Built-in Heater - Integrated heaters that can be switched on in extreme weather.
  • Embedded with the Electronic Compass - Magnetometer: enabling easy installation and you can choose to disable the electronic compass while orienting to the North manually.


  • Weather monitoring for agriculture, meteorology, forestry, ports, railways, schools, and buildings, etc.

Read more →

2.5G Cloud Managed PoE Switch with 10G SFP Uplink and 130W PoE Budget

Andy Chen

cloud managed poe switch

Recently we launched our latest product POE-SWR308G25. It is 2.5G Cloud Managed PoE Switch with 10G SFP Uplink and 130W PoE Budget. 

Outstanding Features: 

  • CLOUD MANAGED PoE SWITCH - Remote monitor and control PoE ports from central Cloud, such as turn On/Off PoE, speed / priority / PoE budget settings; Includes one year free subscription; Also supports VLAN, QoS in local WEB GUI
  • FULL 2.5G PoE SWITCH -Provide 8 x 2500Mbps PoE ports, transmit 2.5x faster speed internet over regular Cat5E/Cat6 network cables; Auto adaptive 10/100/1000M/2.5G
  • 10G SFP UPLINK - Support 10Gbps SFP module, also compatible to 1G or 2.5G SFP modules (SFP module is not included)
  • 130W TOTAL POWER - Each port up to 30W (IEEE802.3af/at), total 130W PoE power; Package includes 150W Power Adapter
2.5x higher speed internet for online gaming, 4K Video, WiFi 6 AP integration, office network, etc.

Read more →

What is a PoE Injector and How to Use It?

Andy Chen

Power over Ethernet (PoE) technology allows the transmission of power and data over Ethernet cabling, using devices such as PoE switches, PoE injectors, and PoE splitters. In situations where power outlets are not readily available, PoE injectors offer a convenient solution for installing low-power devices in hard-to-reach areas without significant infrastructure modifications or budget constraints. This article aims to provide a comprehensive understanding of PoE injectors, including their definition, usage in applications, and answers to frequently asked questions.

What is a PoE Injector?

A PoE injector, also known as a midspan or PoE adapter, enables non-PoE compatible switches to power PoE devices by delivering both power and data over a single Ethernet cable.

Benefits of PoE Injectors:

  • Easy installation: Simply connect the PoE injector to the PoE endpoint and an Ethernet switch to provide data and power.
  • Network expansion flexibility: PoE injectors add PoE capability to non-PoE Ethernet switches, extending the network connection distance and providing combined power and data over Ethernet cables for improved connectivity.
  • Cost-effective solution: By utilizing existing Ethernet equipment and cabling infrastructure, implementing a PoE injector solution minimizes additional costs.
How Does a PoE Injector Work?


When Ethernet switches or other devices lack PoE functionality but need to support Powered Devices (PDs) like PoE IP cameras, PoE wireless access points (WAPs), or PoE lighting, a PoE injector can supply power and data to these PDs over distances of up to 100 meters. Typically, a PoE injector converts alternating current (AC) into direct current (DC) to power low-voltage PoE devices.

Types of PoE Injectors:

1.Active vs. Passive PoE Injector:

A PoE injector following the IEEE 802.3af, IEEE 802.3at, or IEEE 802.3bt standards is known as an active PoE injector. These injectors require a handshake between the power sending and receiving PoE devices. If the receiving device does not provide the proper acknowledgment, the injector will not supply power, ensuring the safety of PoE devices. Active PoE injectors generally operate at a voltage of 44 to 57 volts DC.

In contrast, a passive PoE injector does not conform to the IEEE standards mentioned above. Passive PoE devices usually operate at voltages ranging from 18 to 48 volts DC. Connecting the wrong voltage may cause permanent electrical damage to the device.

2.12V vs. 24V vs. 48V PoE Injector:

PoE injectors can be categorized based on the output power voltage they provide, such as 12V, 24V, or 48V. When selecting a PoE injector, it is crucial to consider the voltage requirements of the powered PoE devices.

Additionally, PoE injectors can also vary based on port numbers, such as single-port PoE injectors, 2-port PoE injectors, and so on.

How to Use a PoE Injector?

PoE injectors excel at providing data and power to standard-based PoE, PoE+, and PoE++ compliant devices. In practical applications, a PoE injector acts as an intermediary between a non-PoE switch and PoE compliant devices, such as IP cameras or wireless access points, delivering power to them.

Take an IP camera as an example. The following steps illustrate the power supply process:

  1. Test all equipment to ensure the IP camera, PoE injector, and camera management system are functioning properly. Configure video and network settings before mounting the IP camera.
  2. Connect the Ethernet cable from the PoE injector's Power or PoE port to the IP camera's PoE port.
  3. Mount the IP camera in a well-lit area to capture clear images.
  4. Connect another Ethernet cable between the injector's Ethernet or Data port and the Ethernet switch.
  5. Plug the injector's power cord into a local AC electrical outlet.

Read more →

What is Solar PoE Switch? Why do you need it in your solar system?

Andy Chen

Have you ever thought about integrating solar controller and PoE Switch and create a single powerful device that allows for solar energy management, battery management, and network data and power management and even has a capability to integrate to larger network? Today, we're thrilled to introduce our latest product line that's set to redefine the way you install, setup, and manage your solar power system! This is Solar PoE Switch. Prior to the PoE Switch, there is Solar, exactly, literally, that stands for Solar Controller and PoE Switch, 2 in 1, industrial PoE Switch with built-in Solar Power Controller. Before we jump right into the details, let's take a quick look at what Solar Controller and PoE Switches are, and how they work in Solar Power systems!

A Solar Controller is a vital component in solar power systems, one of the key function here is that acting as a smart battery charger to safeguard your battery from potential damage. When connecting a battery directly to solar panels without a control device, the risk of overcharging and subsequent damage due to excessive voltage and current becomes a concern. it plays a important role at the entire solar power system.

And as we all know, PoE switches simplify solar system connectivity by combining power and data transmission over a single cable. They enhance efficiency by reducing the need for separate power sources for connected devices in a solar setup. PoE switches facilitate centralized control and monitoring, optimizing the management of solar-powered devices in a streamlined manner.

LINOVISION Solar PoE Switch, is industrial PoE Switch with built-in solar charge controller, working directly with PV solar panels and batteries to supply non-stop PoE power for devices, this is a single highly integrated device that allows for solar energy management, battery management, and remote network data and power management and even has a capability to integrate to larger network!
You might wonder, why did we adopt this design? what would benefit your solar power system?

Combining the solar power controller with a PoE switch into a single fully integrated device offers several pros, here's what we thought through:

  1. Highly Integrated Design: Solar PoE Switch streamlines the installation and maintenance. Users only need to deal with one device instead of separately configuring and managing the solar controller and PoE switch, this integrated design allows for smoother energy flow within the system by optimizing the collaboration between components. From the cost perspective, purchasing a single unit is often a lower cost than buying two separate devices. Additionally, you will save on labor costs associated with installation and maintenance.
  1. Compact Size: The integrated design can decrease the number of devices and overall physical size, saving space. It can eliminate the need for separate cables, power supplies, making installation and maintenance much easier. This is particularly crucial in setups with limited space.
  1. Simplified Deployment and reduced system complexity: the integrated device reduces the complexity of configuring multiple components. Simplifying the device's installation process. It can decrease the technical complexity, especially for users with limited technical expertise.
Meanwhile, the reason we are excited about moving toward this line of products is that some pain points of the existing separate installation approach can be solved.
  1. Complexity of installation: Users would need to individually install solar power controllers and PoE switches, which could consume more time and require additional technical expertise. The configuration process may involve coordinating between different devices. Installing and managing two separate devices is more complex than installing a single integrated device.
  1. Space Occupancy: Independently deployed devices typically require more space, as they cannot be integrated into a relatively compact design. This can be a challenge in applications with space constraints.
  1. Technical Challenges: Configuring two separate devices may pose higher demands on technical personnel. Ensuring effective collaboration between the two systems may require additional technical expertise. Separate systems may require distinct maintenance and monitoring efforts for solar power and PoE networks. This can introduce additional complexity in troubleshooting issues and monitoring overall system performance.
  1. Lack of Integrated User Experience: Users might need to deal with independently sourced devices from different vendors, potentially involving different user interfaces and some incompatible issues.

Read more →

Industrial 8 Ports Full Gigabit Cloud Managed PoE Switch

Andy Chen


POE-SWR308G is LINOVISION 8 Ports Cloud Managed PoE Switch with 2 SFP Uplink, Full Gigabit Ports, 120W Built-in Power Supply, IEEE802.3af/at, Q-PoE and P-PoE Without Interruption.CLOUD MANAGED PoE SWITCH

Remote monitor and control PoE ports from central Cloud, such as turn On/Off PoE, speed / priority / PoE budget settings; Includes one year free subscription; Also supports VLAN, QoS in local WEB GUI.


Provides 8*10/100/1000Base-T Ethernet PoE ports and 2*1000Base-X SFP Uplinks.


Each port up to 30W (IEEE802.3af/at), total 120W PoE power. POE Output Ports support POE Mode A. Power adapter is included and built-in the metal enclosure.

  • Q-PoE AND P-PoE 

Supports Q-PoE (Quick PoE) technology, which enables PoE power supply immediately upon switch startup without waiting for switch system software control. Support P-PoE (Perpetual PoE) technology, which enables PoE power supply without interruption when switch is restarting and restores network quickly.


Automatically identify PD devices for power supply without damaging non-PoE devices.

Read more →

POE Switches Ideal for RV/Truck/Bus/Vehicle/Rail Applications

Andy Chen

Read more →

What's is SFP? What is used for? What's the benefit of SFP to industrial applications?

Andy Chen

Read more →

Linovision New Product - Industrial 8 Ports Full Gigabit PoE Switch with Remote PoE Ports Management

Andy Chen

Read more →