Modbus86 Slave

Posted by On 01 / 30 / 2019 0 Comment

Modbus86 Slave can make 86Duino simulate a Modbus Slave node, receive commands on the channel and execute callback functions.

Example

 Example of a slave device that enables RS485 and uses Modbus RTU as the communication method

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#include <Modbus86.h>

 

ModbusSlave bus;

ModbusSlaveNode node;

 

uint32_t command = 0;

uint32_t lasttime = 0;

 

uint8_t read_holding_registers( uint8_t function,

                                uint16_t address,

                                uint16_t length)

{

    for (int i = address; i < address + length; i++) {

        if (i == 16)

            node.writeHoldingRegister(i, command & 0xFFFF);

        else if (i == 17)

            node.writeHoldingRegister(i, (command >> 16) & 0xFFFF);

    }

     

    return MODBUS_SUCCESS;

}

 

uint8_t read_input_registers(   uint8_t function,

                                uint16_t address,

                                uint16_t length)

{

    int sensorPin = A2;

 

    if (address <= 2 && address + length > 2)

        node.writeInputRegister(2, analogRead(sensorPin));

     

    return MODBUS_SUCCESS;

}

 

uint8_t write_multiple_registers(   uint8_t function,

                                    uint16_t address,

                                    uint16_t length)

{

    int i;

 

    for (i = address; i < address + length; i++) {

        if (i == 16)

            command = (command & 0xFFFF0000) | node.readHoldingRegister(i);

        else if (i == 17)

            command =

                (command & 0x0000FFFF) | (node.readHoldingRegister(i) << 16);

    }

 

    return MODBUS_SUCCESS;

}

 

uint8_t write_single_coil(  uint8_t function,

                            uint16_t address,

                            uint16_t length)

{

    uint16_t value;

     

    if (address == 0) {

        node.readCoil(address, 1, &value);

        if (value)

            digitalWrite(LED_BUILTIN, HIGH);

        else

            digitalWrite(LED_BUILTIN, LOW);

    }

 

    return MODBUS_SUCCESS;

}

 

void setup()

{

    pinMode(LED_BUILTIN, OUTPUT);

     

    Serial485.begin(115200);

     

    /* Modbus RTU Mode via RS485. */

    bus.begin(MODBUS_RTU, Serial485);

     

    /* Slave node with ID 11. */

    node.attach(11, bus);

 

    /* Set the callback function of Read Holding Registers (0x03). */

    node.cbFunc[MODBUS_CB_READ_HOLDING_REGISTERS]

                            = read_holding_registers;

 

    /* Set the callback function of Read Input Registers (0x04). */

    node.cbFunc[MODBUS_CB_READ_INPUT_REGISTERS]

                            = read_input_registers;

     

    /* Set the callback function of Write Single Coil (0x05). */

    node.cbFunc[MODBUS_CB_WRITE_SINGLE_COIL]

                            = write_single_coil;

     

    /* Set the callback function of Write Multiple Registers (0x10). */

    node.cbFunc[MODBUS_CB_WRITE_MULTIPLE_REGISTERS]

                            = write_multiple_registers;

}

 

void loop()

{

    uint32_t now;

     

    node.poll();

     

    now = millis();

    if (now - lasttime > 500) {

        lasttime = now;

        Serial.print("commnad = ");

        Serial.println(command);

    }

}

 Example of a slave device with Ethernet enabled and using Modbus TCP as the communication method

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#include <Ethernet.h>

#include <Modbus86.h>

 

ModbusSlave bus;

ModbusSlaveNode node;

 

byte mac[] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00};

IPAddress localIp(192,168,1,102);

 

uint32_t command = 0;

uint32_t lasttime = 0;

 

uint8_t read_holding_registers( uint8_t function,

                                uint16_t address,

                                uint16_t length)

{

    for (int i = address; i < address + length; i++) {

        if (i == 16)

            node.writeHoldingRegister(i, command & 0xFFFF);

        else if (i == 17)

            node.writeHoldingRegister(i, (command >> 16) & 0xFFFF);

    }

     

    return MODBUS_SUCCESS;

}

 

uint8_t read_input_registers(   uint8_t function,

                                uint16_t address,

                                uint16_t length)

{

    int sensorPin = A2;

 

    if (address <= 2 && address + length > 2)

        node.writeInputRegister(2, analogRead(sensorPin));

     

    return MODBUS_SUCCESS;

}

 

uint8_t write_multiple_registers(   uint8_t function,

                                    uint16_t address,

                                    uint16_t length)

{

    int i;

 

    for (i = address; i < address + length; i++) {

        if (i == 16)

            command = (command & 0xFFFF0000) | node.readHoldingRegister(i);

        else if (i == 17)

            command =

                (command & 0x0000FFFF) | (node.readHoldingRegister(i) << 16);

    }

 

    return MODBUS_SUCCESS;

}

 

uint8_t write_single_coil(  uint8_t function,

                            uint16_t address,

                            uint16_t length)

{

    uint16_t value;

     

    if (address == 0) {

        node.readCoil(address, 1, &value);

        if (value)

            digitalWrite(LED_BUILTIN, HIGH);

        else

            digitalWrite(LED_BUILTIN, LOW);

    }

 

    return MODBUS_SUCCESS;

}

 

void setup()

{

    pinMode(LED_BUILTIN, OUTPUT);

     

    Ethernet.begin(mac, localIp);

     

    /* Modbus TCP Mode via Ethernet. */

    bus.begin(MODBUS_TCP);

     

    /* Slave node initialize. */

    node.attach(11, bus);

 

    /* Set the callback function of Read Holding Registers (0x03). */

    node.cbFunc[MODBUS_CB_READ_HOLDING_REGISTERS]

                            = read_holding_registers;

 

    /* Set the callback function of Read Input Registers (0x04). */

    node.cbFunc[MODBUS_CB_READ_INPUT_REGISTERS]

                            = read_input_registers;

     

    /* Set the callback function of Write Single Coil (0x05). */

    node.cbFunc[MODBUS_CB_WRITE_SINGLE_COIL]

                            = write_single_coil;

     

    /* Set the callback function of Write Multiple Registers (0x10). */

    node.cbFunc[MODBUS_CB_WRITE_MULTIPLE_REGISTERS]

                            = write_multiple_registers;

}

 

void loop()

{

    uint32_t now;

     

    node.poll();

     

    now = millis();

    if (now - lasttime > 500) {

        lasttime = now;

        Serial.print("commnad = ");

        Serial.println(command);

    }

}

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The text of the 86Duino reference is a modification of the Arduino reference, and is licensed under a Creative Commons Attribution-ShareAlike 3.0 License. Code samples in the reference are released into the public domain.