/* It's modbus request on read register by logical address (la) */
	uint16_t user_mbus_somedev_read(uint32_t la){
		switch(la){
			case 40000:
				return my_buffer_reg_4xxxx[0];
			case 40001:
				return some_register_from_you_device;
			...
		}
	}

	//Function for write to some register by logic address
	uint16_t user_mbus_somedev_write(uint32_t la, uint16_t value)
	{
		if ( la >= 40000 && la <= 40013 ){
			my_buffer_reg_4xxxx[la-40000] = value;
		}
		if (la == 40018 ){
			 output = (value >> 8) | (value << 8);
		}
		
    return value;
}	

void HAL_UART_DMA_IdleLineDetect(UART_HandleTypeDef *huart){
	...
	if (huart == &huart1){
		for (i=... {
			mbus_poll(modbus, data[i] );
		}
		clear buffer....
	}
}

	Modbus_Conf_t mb_config;

   /* Device slave address */
    mb_config.devaddr = 0x01;
    /* Device count coils(discrete outputs) */
    mb_config.coils = 8;
    /* Device count discrete (discrete inputs) */
    mb_config.discrete = 8;
    /* Just ptr on any external object, you can get it by context */
    mb_config.device = (void*) 0;

    /* This buffer for data content when we sending data */
    mb_config.sendbuf = s_buf;
    mb_config.sendbuf_sz = sizeof(s_buf);

    /* This that function for sending some data (use sendbuf for buf) */
    mb_config.send = &send;

    /* This buffer for data content when we recv some data (no more then sz) */
    mb_config.recvbuf = r_buf;
    mb_config.recvbuf_sz = sizeof(r_buf);


   	//Read callback function ( read by logical address) 
    pconf->read = user_mbus_somedev_read;
	
	//Write callback function
    pconf->write = user_mbus_somedev_write;
	
	//Open
	mb = mbus_open(pconf);