github.com/simpleiot/simpleiot@v0.18.3/cmd/modbus-server/main.go (about)

     1  // example modbus server application
     2  package main
     3  
     4  import (
     5  	"flag"
     6  	"fmt"
     7  	"log"
     8  	"os"
     9  	"strconv"
    10  	"time"
    11  
    12  	"github.com/simpleiot/simpleiot/modbus"
    13  	"github.com/simpleiot/simpleiot/respreader"
    14  	"go.bug.st/serial"
    15  )
    16  
    17  func usage() {
    18  	fmt.Println("Usage: ")
    19  	flag.PrintDefaults()
    20  	os.Exit(-1)
    21  }
    22  
    23  func main() {
    24  	log.Println("modbus simulator")
    25  
    26  	flagPort := flag.String("port", "", "serial port")
    27  	flagBaud := flag.String("baud", "9600", "baud rate")
    28  
    29  	flag.Parse()
    30  
    31  	if *flagPort == "" {
    32  		usage()
    33  	}
    34  
    35  	baud, err := strconv.Atoi(*flagBaud)
    36  
    37  	if err != nil {
    38  		log.Println("Baud rate error:", err)
    39  		os.Exit(-1)
    40  	}
    41  
    42  	log.Printf("Starting server on: %v, baud: %v", *flagPort, baud)
    43  
    44  	mode := &serial.Mode{
    45  		BaudRate: baud,
    46  	}
    47  	port, err := serial.Open(*flagPort, mode)
    48  	if err != nil {
    49  		log.Fatal(err)
    50  	}
    51  
    52  	portRR := respreader.NewReadWriteCloser(port, time.Second, time.Millisecond*30)
    53  
    54  	transport := modbus.NewRTU(portRR)
    55  
    56  	regs := &modbus.Regs{}
    57  	serv := modbus.NewServer(1, transport, regs, 1)
    58  	regs.AddCoil(128)
    59  	err = regs.WriteCoil(128, true)
    60  	if err != nil {
    61  		log.Println("Error writing coil:", err)
    62  		os.Exit(-1)
    63  	}
    64  
    65  	regs.AddReg(2, 1)
    66  	err = regs.WriteReg(2, 5)
    67  	if err != nil {
    68  		log.Println("Error writing reg:", err)
    69  		os.Exit(-1)
    70  	}
    71  
    72  	// start slave so it can respond to requests
    73  	go serv.Listen(func(err error) {
    74  		log.Println("modbus server listen error:", err)
    75  	}, func() {
    76  		log.Printf("modbus reg changes")
    77  	}, func() {
    78  		log.Printf("modbus listener done")
    79  	})
    80  
    81  	if err != nil {
    82  		log.Println("Error opening modbus port:", err)
    83  	}
    84  
    85  	value := true
    86  	regValue := 0
    87  	up := true
    88  
    89  	for {
    90  		time.Sleep(time.Second * 10)
    91  
    92  		value = !value
    93  		_ = regs.WriteCoil(128, value)
    94  
    95  		if up {
    96  			regValue = regValue + 1
    97  			if regValue >= 10 {
    98  				up = false
    99  			}
   100  		} else {
   101  			regValue = regValue - 1
   102  			if regValue <= 0 {
   103  				up = true
   104  			}
   105  		}
   106  		_ = regs.WriteReg(2, uint16(regValue))
   107  	}
   108  }