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edited May 23, 2018 at 11:14

Juraj ♦

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#include <ModbusRtu.h>

// data array for modbus network sharing uint16_t au16data[64]; uint8_t u8state;

int i;

/**

Modbus object declaration

u8id : node id = 0 for master, = 1..247 for slave

u8serno : serial port (use 0 for Serial)

u8txenpin : 0 for RS-232 and USB-FTDI

          or any pin number > 1 for RS-485

*/ Modbus master(0,0,1); // this is master and RS-232 or USB-FTDI

/**

This is an structe which contains a query to an slave device */ modbus_t telegram;

unsigned long u32wait;

void setup() { master.begin( 9600 ); // baud-rate at 19200 master.setTimeOut( 2000 ); // if there is no answer in 2000 ms, roll over u32wait = millis() + 1000; u8state = 0; }

void loop() { switch( u8state ) { case 0: if (millis() > u32wait) u8state++; // wait state break; case 1: telegram.u8id = 1; // slave address telegram.u8fct = 3; // function code (this one is registers read) telegram.u16RegAdd = 1; // start address in slave telegram.u16CoilsNo = 24; // number of elements (coils or registers) to read telegram.au16reg = au16data; // pointer to a memory array in the Arduino

#include <ModbusRtu.h>

// data array for modbus network sharing
uint16_t au16data[64];
uint8_t u8state;

int i;

/**
 *  Modbus object declaration
 *  u8id : node id = 0 for master, = 1..247 for slave
 *  u8serno : serial port (use 0 for Serial)
 *  u8txenpin : 0 for RS-232 and USB-FTDI 
 *               or any pin number > 1 for RS-485
 */
Modbus master(0,0,1); // this is master and RS-232 or USB-FTDI

/**
 * This is an structe which contains a query to an slave device
 */
modbus_t telegram;

unsigned long u32wait;

void setup() {
  master.begin( 9600 ); // baud-rate at 19200
  master.setTimeOut( 2000 ); // if there is no answer in 2000 ms, roll over
  u32wait = millis() + 1000;
  u8state = 0; 
}

void loop() {
  switch( u8state ) {
  case 0: 
    if (millis() > u32wait) u8state++; // wait state
    break;
  case 1: 
    telegram.u8id = 1; // slave address
    telegram.u8fct = 3; // function code (this one is registers read)
    telegram.u16RegAdd = 1; // start address in slave
    telegram.u16CoilsNo = 24; // number of elements (coils or registers) to read
    telegram.au16reg = au16data; // pointer to a memory array in the Arduino

    master.query( telegram ); // send query (only once)
    u8state++;
    break;
  case 2:
    master.poll(); // check incoming messages
    if (master.getState() == COM_IDLE) {
      u8state = 0;
      u32wait = millis() + 100; 
    }
    break;
  }
 //au16data[4] = analogRead( 0 );

 for(i=0;i<=64;i++)
 {
  Serial.print(au16data[i]);
 }
 Serial.println("\n");
 Serial.println("\n");
 delay(1000);
 }

case 2: master.poll(); // check incoming messages if (master.getState() == COM_IDLE) { u8state = 0; u32wait = millis() + 100; } break; } //au16data[4] = analogRead( 0 );

for(i=0;i<=64;i++) { Serial.print(au16data[i]); } Serial.println("\n"); Serial.println("\n"); delay(1000); }

#include <ModbusRtu.h>

// data array for modbus network sharing uint16_t au16data[64]; uint8_t u8state;

int i;

/**

Modbus object declaration

u8id : node id = 0 for master, = 1..247 for slave

u8serno : serial port (use 0 for Serial)

u8txenpin : 0 for RS-232 and USB-FTDI

          or any pin number > 1 for RS-485

*/ Modbus master(0,0,1); // this is master and RS-232 or USB-FTDI

/**

This is an structe which contains a query to an slave device */ modbus_t telegram;

unsigned long u32wait;

void setup() { master.begin( 9600 ); // baud-rate at 19200 master.setTimeOut( 2000 ); // if there is no answer in 2000 ms, roll over u32wait = millis() + 1000; u8state = 0; }

master.query( telegram ); // send query (only once)
u8state++;
break;

case 2: master.poll(); // check incoming messages if (master.getState() == COM_IDLE) { u8state = 0; u32wait = millis() + 100; } break; } //au16data[4] = analogRead( 0 );

for(i=0;i<=64;i++) { Serial.print(au16data[i]); } Serial.println("\n"); Serial.println("\n"); delay(1000); }

#include <ModbusRtu.h>

// data array for modbus network sharing
uint16_t au16data[64];
uint8_t u8state;

int i;

/**
 *  Modbus object declaration
 *  u8id : node id = 0 for master, = 1..247 for slave
 *  u8serno : serial port (use 0 for Serial)
 *  u8txenpin : 0 for RS-232 and USB-FTDI 
 *               or any pin number > 1 for RS-485
 */
Modbus master(0,0,1); // this is master and RS-232 or USB-FTDI

/**
 * This is an structe which contains a query to an slave device
 */
modbus_t telegram;

unsigned long u32wait;

void setup() {
  master.begin( 9600 ); // baud-rate at 19200
  master.setTimeOut( 2000 ); // if there is no answer in 2000 ms, roll over
  u32wait = millis() + 1000;
  u8state = 0; 
}

void loop() {
  switch( u8state ) {
  case 0: 
    if (millis() > u32wait) u8state++; // wait state
    break;
  case 1: 
    telegram.u8id = 1; // slave address
    telegram.u8fct = 3; // function code (this one is registers read)
    telegram.u16RegAdd = 1; // start address in slave
    telegram.u16CoilsNo = 24; // number of elements (coils or registers) to read
    telegram.au16reg = au16data; // pointer to a memory array in the Arduino

    master.query( telegram ); // send query (only once)
    u8state++;
    break;
  case 2:
    master.poll(); // check incoming messages
    if (master.getState() == COM_IDLE) {
      u8state = 0;
      u32wait = millis() + 100; 
    }
    break;
  }
 //au16data[4] = analogRead( 0 );

 for(i=0;i<=64;i++)
 {
  Serial.print(au16data[i]);
 }
 Serial.println("\n");
 Serial.println("\n");
 delay(1000);
 }

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asked May 23, 2018 at 7:10

user1811790

Arduino Modbus Master code to read data using arduino uno from EB meter

I am using DC energy meter as slave.When I am testing DC energy meter using Modbus tester tool,its showing value from 1 to 24 register.I am using my own atmega328P with on board RS485 as a master device.I have connected A,B from slave to mater board.Now,I want to read slave outputs using my master.For that I have written below mentioned code.when I am serially printing array,its showing 00000000000000000000000000000000769.I am not getting full data on my master.

#include <ModbusRtu.h>

// data array for modbus network sharing uint16_t au16data[64]; uint8_t u8state;

int i;

/**

Modbus object declaration
u8id : node id = 0 for master, = 1..247 for slave
u8serno : serial port (use 0 for Serial)
u8txenpin : 0 for RS-232 and USB-FTDI

          or any pin number > 1 for RS-485

*/ Modbus master(0,0,1); // this is master and RS-232 or USB-FTDI

/**

This is an structe which contains a query to an slave device */ modbus_t telegram;

unsigned long u32wait;

void setup() { master.begin( 9600 ); // baud-rate at 19200 master.setTimeOut( 2000 ); // if there is no answer in 2000 ms, roll over u32wait = millis() + 1000; u8state = 0; }

master.query( telegram ); // send query (only once)
u8state++;
break;

case 2: master.poll(); // check incoming messages if (master.getState() == COM_IDLE) { u8state = 0; u32wait = millis() + 100; } break; } //au16data[4] = analogRead( 0 );

for(i=0;i<=64;i++) { Serial.print(au16data[i]); } Serial.println("\n"); Serial.println("\n"); delay(1000); }

arduino-uno modbus