modjn

Modbus TCP client/server implementation in Java with Netty 4.x

Currently implemented modbus functions

• READ COILS | 0x01
• READ DISCRETE INPUTS | 0x02
• READ HOLDING REGISTERS | 0x03
• READ INPUT REGISTERS | 0x04
• WRITE SINGLE COIL | 0x05
• WRITE SINGLE REGISTER | 0x06
• WRITE MULTIPLE COILS | 0x0F
• WRITE MULTIPLE REGISTERS | 0x10

Usage

Server

implement ModbusRequestHandler for server business logic, example here...

ModbusServer modbusServer = new ModbusServer(502);

try {
    modbusServer.setup(new ModbusRequestHandler());
} catch(ConnectionException ex) {
    System.out.println(ex.getLocalizedMessage());
}

modbusServer.close();

Client

switch to async requests by passing an instance of ModbusResponseHandler to the setup function and handle responses by yourself

ModbusClient modbusClient = new ModbusClient("localhost"; 502);

try {
    modbusClient.setup();

    ReadCoilsResponse readCoils = modbusClient.readCoils(12321, 10);

    //modbusClient.[other functions] ...

    System.out.println(readCoils);
} catch (NoResponseException | ErrorResponseException | ConnectionException ex) {
    System.out.println(ex.getLocalizedMessage());
}

modbusClient.close();