go modbus

modbus write in pure go, support rtu,ascii,tcp master library,also support tcp slave.

Supported formats

• modbus Serial(RTU,ASCII) Client
• modbus TCP Client
• modbus TCP Server

Features

• object pool design,reduce memory allocation
• fast encode and decode
• interface design
• simple API and support raw data api

Installation

Use go get.

    go get github.com/things-go/go-modbus

Then import the package into your own code.

    import modbus "github.com/things-go/go-modbus"

Supported functions

bit access:

• Read Discrete Inputs
• Read Coils
• Write Single Coil
• Write Multiple Coils

16-bit access:

• Read Input Registers
• Read Holding Registers
• Write Single Register
• Write Multiple Registers
• Read/Write Multiple Registers
• Mask Write Register
• Read FIFO Queue

Example

modbus RTU/ASCII client see example

package main

import (
	"fmt"
	"time"

	"github.com/goburrow/serial"

	modbus "github.com/things-go/go-modbus"
)

func main() {
	p := modbus.NewRTUClientProvider(modbus.WithEnableLogger(),
		modbus.WithSerialConfig(serial.Config{
			Address:  "/dev/ttyUSB0",
			BaudRate: 115200,
			DataBits: 8,
			StopBits: 1,
			Parity:   "N",
			Timeout:  modbus.SerialDefaultTimeout,
		}))

	client := modbus.NewClient(p)
	err := client.Connect()
	if err != nil {
		fmt.Println("connect failed, ", err)
		return
	}
	defer client.Close()

	fmt.Println("starting")
	for {
		_, err := client.ReadCoils(3, 0, 10)
		if err != nil {
			fmt.Println(err.Error())
		}

		//	fmt.Printf("ReadDiscreteInputs %#v\r\n", results)

		time.Sleep(time.Second * 2)
	}
}

modbus TCP client see example

package main

import (
	"fmt"
	"time"

	modbus "github.com/things-go/go-modbus"
)

func main() {
	p := modbus.NewTCPClientProvider("192.168.199.188:502", modbus.WithEnableLogger())
	client := modbus.NewClient(p)
	err := client.Connect()
	if err != nil {
		fmt.Println("connect failed, ", err)
		return
	}
	defer client.Close()

	fmt.Println("starting")
	for {
		_, err := client.ReadCoils(1, 0, 10)
		if err != nil {
			fmt.Println(err.Error())
		}

		//	fmt.Printf("ReadDiscreteInputs %#v\r\n", results)

		time.Sleep(time.Second * 2)
	}
}

modbus TCP server see example

package main

import (
	modbus "github.com/things-go/go-modbus"
)

func main() {
	srv := modbus.NewTCPServer()
	srv.LogMode(true)
	srv.AddNodes(
		modbus.NewNodeRegister(
			1,
			0, 10, 0, 10,
			0, 10, 0, 10),
		modbus.NewNodeRegister(
			2,
			0, 10, 0, 10,
			0, 10, 0, 10),
		modbus.NewNodeRegister(
			3,
			0, 10, 0, 10,
			0, 10, 0, 10))

	err := srv.ListenAndServe(":502")
	if err != nil {
		panic(err)
	}
}

References

• Modbus Specifications and Implementation Guides
• goburrow

JetBrains OS licenses

go-modbus had been being developed with GoLand under the free JetBrains Open Source license(s) granted by JetBrains s.r.o., hence I would like to express my thanks here.

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