ESP8266 WiFi - Modbus TCP/IP Slave

Hardware: ESP8266 WiFi

Het is mogelijk om een Modbus TCP/IP Slave te maken met de ESP8266 chip op diverse platformen, hieronder een aantal voorbeelden.

Voorbeeld ZONDER bibliotheek

Bron: trialcommand.com

Info (ENG):

We performed numerous tests of the modbus library which used the Tinker library, with the result that certain applications that use delay’s affect communication, in that case we take the library and select the connection routines, master frame reading, frame creation, Reading and writing functions.

This routine created in Arduino IDE for ESP8266 performs master – slave communication without adding extra libraries, since the communication is done step by step.

Tests:
The following addresses have been configured in the ESP8266 module:

10 Holding Read Registers for display on the ESP8266 serial terminal.
10 Holding Writing Registers in which we will send Random values to validate the changes in the Modbus Master (Simulator).
Additionally from Holding register [14] we will activate the 14 – pin GPIO (D5)

#include <ESP8266WiFi.h>
 
const char* ssid = "SSID";
const char* password = "WACHTWOORD";
int ModbusTCP_port = 502;
 
//////// Required for Modbus TCP / IP /// Requerido para Modbus TCP/IP /////////
#define maxInputRegister 20
#define maxHoldingRegister 20
 
#define MB_FC_NONE 0
#define MB_FC_READ_REGISTERS 3 //implemented
#define MB_FC_WRITE_REGISTER 6 //implemented
#define MB_FC_WRITE_MULTIPLE_REGISTERS 16 //implemented
//
// MODBUS Error Codes
//
#define MB_EC_NONE 0
#define MB_EC_ILLEGAL_FUNCTION 1
#define MB_EC_ILLEGAL_DATA_ADDRESS 2
#define MB_EC_ILLEGAL_DATA_VALUE 3
#define MB_EC_SLAVE_DEVICE_FAILURE 4
//
// MODBUS MBAP offsets
//
#define MB_TCP_TID 0
#define MB_TCP_PID 2
#define MB_TCP_LEN 4
#define MB_TCP_UID 6
#define MB_TCP_FUNC 7
#define MB_TCP_REGISTER_START 8
#define MB_TCP_REGISTER_NUMBER 10
 
byte ByteArray[260];
unsigned int MBHoldingRegister[maxHoldingRegister];
 
//////////////////////////////////////////////////////////////////////////
 
WiFiServer MBServer(ModbusTCP_port);
 
void setup() {
  pinMode(14, OUTPUT);
 
  Serial.begin(9600);
  delay(100);
  WiFi.begin(ssid, password);
  delay(100);
  Serial.println(".");
 
  while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); }

  MBServer.begin();
  Serial.println("Connected ");
  Serial.print("ESP8266 Slave Modbus TCP/IP ");
  Serial.print(WiFi.localIP()); Serial.print(":"); Serial.println(String(ModbusTCP_port));
  Serial.println("Modbus TCP/IP Online");
}
 
 
void loop() {
  // Check if a client has connected // Modbus TCP/IP
  WiFiClient client = MBServer.available();
  if (!client) { return; }

  boolean flagClientConnected = 0;
  byte byteFN = MB_FC_NONE;
  int Start;
  int WordDataLength;
  int ByteDataLength;
  int MessageLength;
 
  // Modbus TCP/IP
  while (client.connected()) {
    if(client.available()) {
      flagClientConnected = 1;
      int i = 0;
      while(client.available()) {
        ByteArray[i] = client.read();
        i++;
      }
      client.flush();
 
      ///// code here --- codigo aqui
 
      ///////// Holding Register [0] A [9] = 10 Holding Registers Escritura
      ///////// Holding Register [0] A [9] = 10 Holding Registers Writing
 
      MBHoldingRegister[0] = random(0,12);
      MBHoldingRegister[1] = random(0,12);
      MBHoldingRegister[2] = random(0,12);
      MBHoldingRegister[3] = random(0,12);
      MBHoldingRegister[4] = random(0,12);
      MBHoldingRegister[5] = random(0,12);
      MBHoldingRegister[6] = random(0,12);
      MBHoldingRegister[7] = random(0,12);
      MBHoldingRegister[8] = random(0,12);
      MBHoldingRegister[9] = random(0,12);

      ///////// Holding Register [10] A [19] = 10 Holding Registers Lectura
      ///// Holding Register [10] A [19] = 10 Holding Registers Reading

      int Temporal[10];

      Temporal[0] = MBHoldingRegister[10];
      Temporal[1] = MBHoldingRegister[11];
      Temporal[2] = MBHoldingRegister[12];
      Temporal[3] = MBHoldingRegister[13];
      Temporal[4] = MBHoldingRegister[14];
      Temporal[5] = MBHoldingRegister[15];
      Temporal[6] = MBHoldingRegister[16];
      Temporal[7] = MBHoldingRegister[17];
      Temporal[8] = MBHoldingRegister[18];
      Temporal[9] = MBHoldingRegister[19];
 
      /// Enable Output 14
      digitalWrite(14, MBHoldingRegister[14] );
 
      //// debug
      for (int i = 0; i < 10; i++) {
       Serial.print("[");
        Serial.print(i);
        Serial.print("] ");
        Serial.print(Temporal[i]);
      }
      Serial.println("");
 
      //// end code - fin 
 
 
      //// routine Modbus TCP
      byteFN = ByteArray[MB_TCP_FUNC];
      Start = word(ByteArray[MB_TCP_REGISTER_START],ByteArray[MB_TCP_REGISTER_START+1]);
      WordDataLength = word(ByteArray[MB_TCP_REGISTER_NUMBER],ByteArray[MB_TCP_REGISTER_NUMBER+1]);
    }
 
    // Handle request
    switch(byteFN) {

      case MB_FC_NONE:
        break;
 
      case MB_FC_READ_REGISTERS: // 03 Read Holding Registers
        ByteDataLength = WordDataLength * 2;
        ByteArray[5] = ByteDataLength + 3; //Number of bytes after this one.
        ByteArray[8] = ByteDataLength; //Number of bytes after this one (or number of bytes of data).
        for(int i = 0; i < WordDataLength; i++) {
          ByteArray[ 9 + i * 2] = highByte(MBHoldingRegister[Start + i]);
          ByteArray[10 + i * 2] = lowByte(MBHoldingRegister[Start + i]);
        }
        MessageLength = ByteDataLength + 9;
        client.write((const uint8_t *)ByteArray,MessageLength);
        byteFN = MB_FC_NONE;
        break;
  
      case MB_FC_WRITE_REGISTER: // 06 Write Holding Register
        MBHoldingRegister[Start] = word(ByteArray[MB_TCP_REGISTER_NUMBER],ByteArray[MB_TCP_REGISTER_NUMBER+1]);
        ByteArray[5] = 6; //Number of bytes after this one.
        MessageLength = 12;
        client.write((const uint8_t *)ByteArray,MessageLength);
        byteFN = MB_FC_NONE;
        break;
 
      case MB_FC_WRITE_MULTIPLE_REGISTERS: //16 Write Holding Registers
        ByteDataLength = WordDataLength * 2;
        ByteArray[5] = ByteDataLength + 3; //Number of bytes after this one.
        for(int i = 0; i < WordDataLength; i++) {
          MBHoldingRegister[Start + i] = word(ByteArray[ 13 + i * 2],ByteArray[14 + i * 2]);
        }
        MessageLength = 12;
        client.write((const uint8_t *)ByteArray,MessageLength); 
        byteFN = MB_FC_NONE;
        break;
    }
  }
}

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#include <ESP8266WiFi.h>

const char* ssid = "SSID";

const char* password = "WACHTWOORD";

int ModbusTCP_port = 502;

//////// Required for Modbus TCP / IP /// Requerido para Modbus TCP/IP /////////

#define maxInputRegister 20

#define maxHoldingRegister 20

#define MB_FC_NONE 0

#define MB_FC_READ_REGISTERS 3 //implemented

#define MB_FC_WRITE_REGISTER 6 //implemented

#define MB_FC_WRITE_MULTIPLE_REGISTERS 16 //implemented

// MODBUS Error Codes

#define MB_EC_NONE 0

#define MB_EC_ILLEGAL_FUNCTION 1

#define MB_EC_ILLEGAL_DATA_ADDRESS 2

#define MB_EC_ILLEGAL_DATA_VALUE 3

#define MB_EC_SLAVE_DEVICE_FAILURE 4

// MODBUS MBAP offsets

#define MB_TCP_TID 0

#define MB_TCP_PID 2

#define MB_TCP_LEN 4

#define MB_TCP_UID 6

#define MB_TCP_FUNC 7

#define MB_TCP_REGISTER_START 8

#define MB_TCP_REGISTER_NUMBER 10

byte ByteArray[260];

unsigned int MBHoldingRegister[maxHoldingRegister];

//////////////////////////////////////////////////////////////////////////

WiFiServer MBServer(ModbusTCP_port);

void setup() {

pinMode(14, OUTPUT);

Serial.begin(9600);

delay(100);

WiFi.begin(ssid, password);

delay(100);

Serial.println(".");

while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); }

MBServer.begin();

Serial.println("Connected ");

Serial.print("ESP8266 Slave Modbus TCP/IP ");

Serial.print(WiFi.localIP()); Serial.print(":"); Serial.println(String(ModbusTCP_port));

Serial.println("Modbus TCP/IP Online");

}

void loop() {

// Check if a client has connected // Modbus TCP/IP

WiFiClient client = MBServer.available();

if (!client) { return; }

boolean flagClientConnected = 0;

byte byteFN = MB_FC_NONE;

int Start;

int WordDataLength;

int ByteDataLength;

int MessageLength;

// Modbus TCP/IP

while (client.connected()) {

if(client.available()) {

flagClientConnected = 1;

int i = 0;

while(client.available()) {

ByteArray[i] = client.read();

i++;

}

client.flush();

///// code here --- codigo aqui

///////// Holding Register [0] A [9] = 10 Holding Registers Escritura

///////// Holding Register [0] A [9] = 10 Holding Registers Writing

MBHoldingRegister[0] = random(0,12);

MBHoldingRegister[1] = random(0,12);

MBHoldingRegister[2] = random(0,12);

MBHoldingRegister[3] = random(0,12);

MBHoldingRegister[4] = random(0,12);

MBHoldingRegister[5] = random(0,12);

MBHoldingRegister[6] = random(0,12);

MBHoldingRegister[7] = random(0,12);

MBHoldingRegister[8] = random(0,12);

MBHoldingRegister[9] = random(0,12);

///////// Holding Register [10] A [19] = 10 Holding Registers Lectura

///// Holding Register [10] A [19] = 10 Holding Registers Reading

int Temporal[10];

Temporal[0] = MBHoldingRegister[10];

Temporal[1] = MBHoldingRegister[11];

Temporal[2] = MBHoldingRegister[12];

Temporal[3] = MBHoldingRegister[13];

Temporal[4] = MBHoldingRegister[14];

Temporal[5] = MBHoldingRegister[15];

Temporal[6] = MBHoldingRegister[16];

Temporal[7] = MBHoldingRegister[17];

Temporal[8] = MBHoldingRegister[18];

Temporal[9] = MBHoldingRegister[19];

/// Enable Output 14

digitalWrite(14, MBHoldingRegister[14] );

//// debug

for (int i = 0; i < 10; i++) {

Serial.print("[");

Serial.print(i);

Serial.print("] ");

Serial.print(Temporal[i]);

}

Serial.println("");

//// end code - fin

//// routine Modbus TCP

byteFN = ByteArray[MB_TCP_FUNC];

Start = word(ByteArray[MB_TCP_REGISTER_START],ByteArray[MB_TCP_REGISTER_START+1]);

WordDataLength = word(ByteArray[MB_TCP_REGISTER_NUMBER],ByteArray[MB_TCP_REGISTER_NUMBER+1]);

}

// Handle request

switch(byteFN) {

case MB_FC_NONE:

break;

case MB_FC_READ_REGISTERS: // 03 Read Holding Registers

ByteDataLength = WordDataLength * 2;

ByteArray[5] = ByteDataLength + 3; //Number of bytes after this one.

ByteArray[8] = ByteDataLength; //Number of bytes after this one (or number of bytes of data).

for(int i = 0; i < WordDataLength; i++) {

ByteArray[ 9 + i * 2] = highByte(MBHoldingRegister[Start + i]);

ByteArray[10 + i * 2] = lowByte(MBHoldingRegister[Start + i]);

}

MessageLength = ByteDataLength + 9;

client.write((const uint8_t *)ByteArray,MessageLength);

byteFN = MB_FC_NONE;

break;

case MB_FC_WRITE_REGISTER: // 06 Write Holding Register

MBHoldingRegister[Start] = word(ByteArray[MB_TCP_REGISTER_NUMBER],ByteArray[MB_TCP_REGISTER_NUMBER+1]);

ByteArray[5] = 6; //Number of bytes after this one.

MessageLength = 12;

client.write((const uint8_t *)ByteArray,MessageLength);

byteFN = MB_FC_NONE;

break;

case MB_FC_WRITE_MULTIPLE_REGISTERS: //16 Write Holding Registers

ByteDataLength = WordDataLength * 2;

ByteArray[5] = ByteDataLength + 3; //Number of bytes after this one.

for(int i = 0; i < WordDataLength; i++) {

MBHoldingRegister[Start + i] = word(ByteArray[ 13 + i * 2],ByteArray[14 + i * 2]);

}

MessageLength = 12;

client.write((const uint8_t *)ByteArray,MessageLength);

byteFN = MB_FC_NONE;

break;

}

Algemeen voorbeeld uitlezen met Python op Raspberry Pi

#!/usr/bin/env python
from pyModbusTCP.client import ModbusClient

client = ModbusClient(host="192.168.2.28", port=502, auto_open=True, auto_close=True, timeout=10)
data2 = client.write_single_register(14, 1) # FUNCTIE 06 - Schrijven (enkele register) (register=14, waarde=1)
data = client.read_holding_registers(14, 1) # FUNCTIE 03 - Lees register (enkele register) (register=14, lengte=1)
print "Waarde register: ", data[0]
client.close()

#!/usr/bin/env python

from pyModbusTCP.client import ModbusClient

client = ModbusClient(host="192.168.2.28", port=502, auto_open=True, auto_close=True, timeout=10)

data2 = client.write_single_register(14, 1) # FUNCTIE 06 - Schrijven (enkele register) (register=14, waarde=1)

data = client.read_holding_registers(14, 1) # FUNCTIE 03 - Lees register (enkele register) (register=14, lengte=1)

print "Waarde register: ", data[0]

client.close()

Zoeken

ESP8266 WiFi – Modbus TCP/IP Slave

Voorbeeld ZONDER bibliotheek

Algemeen voorbeeld uitlezen met Python op Raspberry Pi