A modern, performant, easy to use client and server implementation of Modbus TCP, Modbus RTU/TCP, and Modbus RTU/Serial for Java 17+.

Quick Start Examples

Modbus TCP Client

var transport = NettyTcpClientTransport.create(cfg -> {
  cfg.hostname = "172.17.0.2";
  cfg.port = 502;
});

var client = ModbusTcpClient.create(transport);
client.connect();

ReadHoldingRegistersResponse response = client.readHoldingRegisters(
    1,
    new ReadHoldingRegistersRequest(0, 10)
);

System.out.println("Response: " + response);

Modbus RTU/Serial Client

var transport = SerialPortClientTransport.create(cfg -> {
  cfg.serialPort = "/dev/ttyUSB0";
  cfg.baudRate = 115200;
  cfg.dataBits = 8;
  cfg.parity = SerialPort.NO_PARITY;
  cfg.stopBits = SerialPort.ONE_STOP_BIT;
});

var client = ModbusRtuClient.create(transport);
client.connect();

client.readHoldingRegisters(
    1,
    new ReadHoldingRegistersRequest(0, 10)
);

System.out.println("Response: " + response);

Maven

Modbus TCP

<dependency>
    <groupId>com.digitalpetri.modbus</groupId>
    <artifactId>modbus-tcp</artifactId>
    <version>2.0.1</version>
</dependency>

Modbus Serial

<dependency>
    <groupId>com.digitalpetri.modbus</groupId>
    <artifactId>modbus-serial</artifactId>
    <version>2.0.1</version>
</dependency>

Features

Supported Function Codes

Code	Function	Client	Server
0x01	Read Coils	✅	✅
0x02	Read Discrete Inputs	✅	✅
0x03	Read Holding Registers	✅	✅
0x04	Read Input Registers	✅	✅
0x05	Write Single Coil	✅	✅
0x06	Write Single Register	✅	✅
0x0F	Write Multiple Coils	✅	✅
0x10	Write Multiple Registers	✅	✅
0x16	Mask Write Register	✅	✅
0x17	Read/Write Multiple Registers	✅	✅

• raw/custom PDUs on Modbus/TCP
• broadcast messages on Modbus/RTU
• pluggable codec implementations
• pluggable transport implementations

License

Eclipse Public License - v 2.0