ESP32 Forum

Posted: **Fri Apr 14, 2023 6:14 am**

Hi,

I made ModbusTCP slave based on the esp-idf examples.

It works but the floating point byte order is not understood by the connected Modbus master.

I need to make an extra data array just for the Modbus data transfer. Is there any way just change the byte order in esp-idf Modbus library?

This is my solution at the moment:

Code: [Select all] [Expand/Collapse]

void DataExchange::updateModbusArray() 
{
    for(int i=0; i < _numElements; i++)
    {
        _modbusArray[i*4+0] = *((char*)_dataArray + i*4+2);
        _modbusArray[i*4+1] = *((char*)_dataArray + i*4+3);
        _modbusArray[i*4+2] = *((char*)_dataArray + i*4+0);
        _modbusArray[i*4+3] = *((char*)_dataArray + i*4+1);
    }
}

GeSHi © Codebox Plus Extension

BR, Ilkka

Posted: **Fri Apr 14, 2023 9:35 am**

Is there any way just change the byte order in esp-idf Modbus library?

There may be, cf. viewtopic.php?f=2&t=23040

Posted: **Wed Apr 19, 2023 7:47 am**

Hi,I cannot edit the esp-idf managed component directly. Is there any other way..?

Just mean the function :

Code: Select all

static esp_err_t mbc_serial_master_get_parameter(uint16_t cid, char* name, uint8_t* value_ptr, uint8_t *type)

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