readHoldingRegister()

Posted by On 01 / 31 / 2019 0 Comment

描述

讀取 Holding Registers 暫存器。

語法

node1.readHoldingRegister(address) node2.readHoldingRegister(address, size, buffer)

參數

node1/node2： ModbusSlaveNode 物件。

address：欲讀取的 Holding Registers 暫存器位址。

size：欲讀取的 Holding Registers 暫存器數量。

buffer：將讀取出的 Holding Registers 暫存器陣列資料複寫至 buffer 指向的陣列空間內。

回傳

int：僅使用address引數時回傳該 HoldingRegister 位置資料。 使用指定buffer讀取時，則回傳MODBUS_SUCCESS，反之回傳 EXCEPTION_CODE 。

範例

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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 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;

}

 

void setup()

{   

    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 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);

    }

}

See Also

－ writeHoldingRegister()

函式庫參考主頁面

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