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stm32 modbus

sreedharan1196
Associate II

I am working on stm32u0 with ultrasonic flow meter, i am facing an issue to receive the response from the device using Modbus communication

 

#include "main.h"
#include <stdio.h>
#include <string.h>
#include <stdint.h>
 
#define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#define GETCHAR_PROTOTYPE int __io_getchar(void)
#define MODBUS_SLAVE_ID 0x01
#define MODBUS_FUNCTION_READ_HOLDING_REGISTERS 0x03
uint8_t uart2_tx_data[8];
uint8_t uart2_rx_data[15];
uint16_t recv_data[2];
 
#define DATA_REGISTER_START_POSITIVE 115  // Positive accumulator value
#define DATA_REGISTER_START_NEGATIVE 117  // Negative accumulator value
#define DATA_REGISTER_START_NET      119  // Net accumulator value
 
int REGISTERS_TO_READ = 0x02;    // Number of registers to read
 
UART_HandleTypeDef hlpuart1;
UART_HandleTypeDef huart3;
 
PUTCHAR_PROTOTYPE
{
    HAL_UART_Transmit(&huart3, (uint8_t *)&ch, 1, HAL_MAX_DELAY);
    return ch;
}
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_USART3_UART_Init(void);
static void MX_LPUART1_UART_Init(void);
 
void modbusPreTransmission(void);
void modbusPostTransmission(void);
void sendModbusRequest(uint8_t *request, uint8_t len);
void ultrasonic_value(int DATA_REGISTER_START, int REGISTERS_TO_READ);
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart);
 
void modbus_tx_data()
{
 
    uint8_t slaveAddress = MODBUS_SLAVE_ID;
    uint8_t functionCode = MODBUS_FUNCTION_READ_HOLDING_REGISTERS;
    uint16_t startAddress = DATA_REGISTER_START_POSITIVE-1;
    uint8_t numRegistersHigh = 0x00;
    uint8_t numRegistersLow = REGISTERS_TO_READ;
 
    uart2_tx_data[0] = slaveAddress;
    uart2_tx_data[1] = functionCode;
    uart2_tx_data[2] = startAddress >> 8;
    uart2_tx_data[3] = startAddress & 0xFF;
    uart2_tx_data[4] = numRegistersHigh;
    uart2_tx_data[5] = numRegistersLow;
    uint16_t crc = crc16(uart2_tx_data, 6);
    uart2_tx_data[6] = crc & 0xFF;
    uart2_tx_data[7] = (crc >> 8) & 0xFF;
 
    printf("The Uart_tx buffer: ");
    for (int i = 0; i < 8; ++i)
    {
        printf("%02X ", uart2_tx_data[i]);
    }
    printf("\r\n");
 
    sendModbusRequest(uart2_tx_data, 8);
}
 
void modbusPreTransmission()
{
printf("Date pin enabled........\r\n");
    HAL_GPIO_WritePin(data_enable_GPIO_Port, data_enable_Pin, GPIO_PIN_SET);
    HAL_Delay(1000);
}
 
void modbusPostTransmission()
{
printf("Data pin disabled......\r\n");
    HAL_GPIO_WritePin(data_enable_GPIO_Port, data_enable_Pin, GPIO_PIN_RESET);
    HAL_Delay(1000);
}
 
void sendModbusRequest(uint8_t *request, uint8_t len)
{
    printf("Sending data to the Modbus...\r\n");
    modbusPreTransmission();
    if (HAL_UART_Transmit(&hlpuart1, request, len, 2000) == HAL_OK)
    {
        printf("\nSuccess : UART transmit done\r\n\n");
    }
    else
    {
        printf("\nError : UART transmit failed\r\n\n");
        return;
    }
 
    modbusPostTransmission();
 
    printf("Waiting for response...\r\n");
        HAL_Delay(100); // Adjust delay as necessary
 
        if (HAL_UART_Receive(&hlpuart1, uart2_rx_data, 7 + (2 * REGISTERS_TO_READ), 2000) == HAL_OK)
        {
            printf("Received data from Modbus: ");
            for (int i = 0; i < (7 + 2 * REGISTERS_TO_READ); ++i)
            {
                printf("%02X ", uart2_rx_data[i]);
            }
            printf("\r\n");
        }
        else
        {
            printf("Error: UART receive failed\r\n");
        }
}
 
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
    if (huart->Instance == LPUART1)
    {
        if (uart2_rx_data[1] == MODBUS_FUNCTION_READ_HOLDING_REGISTERS)
        {
            for (int i = 0; i < REGISTERS_TO_READ; i++)
            {
                recv_data[i] = (uart2_rx_data[3 + 2*i] << 8) | uart2_rx_data[4 + 2*i];
            }
 
            float data = *(float*)&recv_data;
 
            printf("Register Data: %f\r\n", data);
        }
        else
        {
            printf("Received unexpected data\r\n");
        }
    }
}
 
uint16_t crc16(uint16_t crc, uint8_t *data, uint32_t length)
{
  int i;
  crc ^= length;
  for (i = 0; i < 8; ++i)
  {
    if (crc & 1)
      crc = (crc >> 1) ^ 0xA001;
    else
      crc = (crc >> 1);
  }
  printf("The CRC : %x",crc);
 
  return crc;
}
int main(void)
{
  HAL_Init();
  SystemClock_Config();
  MX_GPIO_Init();
  MX_USART3_UART_Init();
  MX_LPUART1_UART_Init();
  printf("Welcome to stm32.......\r\n");
  HAL_Delay(2000);
  while (1)
  {
     modbus_tx_data();
HAL_Delay(5000);
  }
}
 
6 REPLIES 6

Please see the posting guidelines - particularly how to properly post source code:

https://community.st.com/t5/community-guidelines/how-to-write-your-question-to-maximize-your-chances-to-find-a/ta-p/575228

 


@sreedharan1196 wrote:

I am working on stm32u0 with ultrasonic flow meter,


Please give the full part number of the STM32, and details of the flow meter

 


@sreedharan1196 wrote:

i am facing an issue to receive the response from the device using Modbus communication


What issue, exactly?

What testing/investigation/debugging have you done to find the problem?

 

Not clear how the callback will occur here.

Blindly waiting for a large block of data is probably not going to work.

You have minimal control of the synchronization of received data, nor the ultimate length.

You should perhaps recover a byte at a time, building a frame, getting it synchronized, and check CRC over the frame. Once you have a full valid frame, pass that on to another subroutine or process to decode / unpack.

Do you have any colleagues or a supervisor who can work through the issues with you locally?

Tips, Buy me a coffee, or three.. PayPal Venmo
Up vote any posts that you find helpful, it shows what's working..
/* USER CODE BEGIN Header */ /** ****************************************************************************** * @file : main.c * @brief : Main program body ****************************************************************************** * @attention * * Copyright (c) 2024 STMicroelectronics. * All rights reserved. * * This software is licensed under terms that can be found in the LICENSE file * in the root directory of this software component. * If no LICENSE file comes with this software, it is provided AS-IS. * ****************************************************************************** */ /* USER CODE END Header */ /* Includes ------------------------------------------------------------------*/ #include "main.h" /* Private includes ----------------------------------------------------------*/ /* USER CODE BEGIN Includes */ #include <stdio.h> #include <string.h> #include <stdint.h> #include "modbus_crc.h" /* USER CODE END Includes */ /* Private typedef -----------------------------------------------------------*/ /* USER CODE BEGIN PTD */ #define PUTCHAR_PROTOTYPE int __io_putchar(int ch) #define GETCHAR_PROTOTYPE int __io_getchar(void) #define MODBUS_SLAVE_ID 0x01 #define MODBUS_FUNCTION_READ_HOLDING_REGISTERS 0x03 uint8_t uart2_tx_data[8]; uint8_t uart2_rx_data[15]; uint16_t recv_data[2]; #define DATA_REGISTER_START_POSITIVE 115 // Positive accumulator value #define DATA_REGISTER_START_NEGATIVE 117 // Negative accumulator value #define DATA_REGISTER_START_NET 119 // Net accumulator value int REGISTERS_TO_READ = 0x02; // Number of registers to read /* USER CODE END PTD */ /* Private define ------------------------------------------------------------*/ /* USER CODE BEGIN PD */ /* USER CODE END PD */ /* Private macro -------------------------------------------------------------*/ /* USER CODE BEGIN PM */ /* USER CODE END PM */ /* Private variables ---------------------------------------------------------*/ UART_HandleTypeDef hlpuart1; UART_HandleTypeDef huart3; /* USER CODE BEGIN PV */ PUTCHAR_PROTOTYPE { HAL_UART_Transmit(&huart3, (uint8_t *)&ch, 1, HAL_MAX_DELAY); return ch; } /* USER CODE END PV */ /* Private function prototypes -----------------------------------------------*/ void SystemClock_Config(void); static void MX_GPIO_Init(void); static void MX_USART3_UART_Init(void); static void MX_LPUART1_UART_Init(void); /* USER CODE BEGIN PFP */ void modbusPreTransmission(void); void modbusPostTransmission(void); void sendModbusRequest(uint8_t *request, uint8_t len); void ultrasonic_value(int DATA_REGISTER_START, int REGISTERS_TO_READ); void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart); /* USER CODE END PFP */ /* Private user code ---------------------------------------------------------*/ /* USER CODE BEGIN 0 */ void modbus_tx_data() { uint8_t slaveAddress = MODBUS_SLAVE_ID; uint8_t functionCode = MODBUS_FUNCTION_READ_HOLDING_REGISTERS; uint16_t startAddress = DATA_REGISTER_START_POSITIVE-1; uint8_t numRegistersHigh = 0x00; uint8_t numRegistersLow = REGISTERS_TO_READ; uart2_tx_data[0] = slaveAddress; uart2_tx_data[1] = functionCode; uart2_tx_data[2] = startAddress >> 8; uart2_tx_data[3] = startAddress & 0xFF; uart2_tx_data[4] = numRegistersHigh; uart2_tx_data[5] = numRegistersLow; // // uint8_t frame[] = {0x01, 0x03, 0x00, 0x72, 0x00, 0x02}; // uint16_t len = sizeof(frame) / sizeof(frame[0]); // // uint16_t crc = crc16(frame, len-1); uint16_t crc = crc16(uart2_tx_data, 6); uart2_tx_data[6] = crc & 0xFF; uart2_tx_data[7] = (crc >> 8) & 0xFF; printf("The Uart_tx buffer: "); for (int i = 0; i < 8; ++i) { printf("%02X ", uart2_tx_data[i]); } printf("\r\n"); sendModbusRequest(uart2_tx_data, 8); } void modbusPreTransmission() { printf("Date pin enabled........\r\n"); HAL_GPIO_WritePin(data_enable_GPIO_Port, data_enable_Pin, GPIO_PIN_SET); HAL_Delay(1000); } void modbusPostTransmission() { printf("Data pin disabled......\r\n"); HAL_GPIO_WritePin(data_enable_GPIO_Port, data_enable_Pin, GPIO_PIN_RESET); HAL_Delay(1000); } void sendModbusRequest(uint8_t *request, uint8_t len) { printf("Sending data to the Modbus...\r\n"); modbusPreTransmission(); if (HAL_UART_Transmit(&hlpuart1, request, len, 2000) == HAL_OK) { printf("\nSuccess : UART transmit done\r\n\n"); } else { printf("\nError : UART transmit failed\r\n\n"); return; } modbusPostTransmission(); printf("Waiting for response...\r\n"); HAL_Delay(100); // Adjust delay as necessary if (HAL_UART_Receive(&hlpuart1, uart2_rx_data, 7 + (2 * REGISTERS_TO_READ), 2000) == HAL_OK) { printf("Received data from Modbus: "); for (int i = 0; i < (7 + 2 * REGISTERS_TO_READ); ++i) { printf("%02X ", uart2_rx_data[i]); } printf("\r\n"); } else { printf("Error: UART receive failed\r\n"); } } void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) { if (huart->Instance == LPUART1) { if (uart2_rx_data[1] == MODBUS_FUNCTION_READ_HOLDING_REGISTERS) { for (int i = 0; i < REGISTERS_TO_READ; i++) { recv_data[i] = (uart2_rx_data[3 + 2*i] << 8) | uart2_rx_data[4 + 2*i]; } float data = *(float*)&recv_data; printf("Register Data: %f\r\n", data); } else { printf("Received unexpected data\r\n"); } } } uint16_t crc16(uint16_t crc, uint8_t *data, uint32_t length) { int i; crc ^= length; for (i = 0; i < 8; ++i) { if (crc & 1) crc = (crc >> 1) ^ 0xA001; else crc = (crc >> 1); } printf("The CRC : %x",crc); return crc; } /* USER CODE END 0 */ /** * @brief The application entry point. * @retval int */ int main(void) { /* USER CODE BEGIN 1 */ /* USER CODE END 1 */ /* MCU Configuration--------------------------------------------------------*/ /* Reset of all peripherals, Initializes the Flash interface and the Systick. */ HAL_Init(); /* USER CODE BEGIN Init */ /* USER CODE END Init */ /* Configure the system clock */ SystemClock_Config(); /* USER CODE BEGIN SysInit */ /* USER CODE END SysInit */ /* Initialize all configured peripherals */ MX_GPIO_Init(); MX_USART3_UART_Init(); MX_LPUART1_UART_Init(); /* USER CODE BEGIN 2 */ printf("Welcome to stm32.......\r\n"); HAL_Delay(2000); /* USER CODE END 2 */ /* Infinite loop */ /* USER CODE BEGIN WHILE */ while (1) { modbus_tx_data(); HAL_Delay(5000); /* USER CODE END WHILE */ /* USER CODE BEGIN 3 */ } /* USER CODE END 3 */ } /** * @brief System Clock Configuration * @retval None */ void SystemClock_Config(void) { RCC_OscInitTypeDef RCC_OscInitStruct = {0}; RCC_ClkInitTypeDef RCC_ClkInitStruct = {0}; /** Configure the main internal regulator output voltage */ HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE2); /** Initializes the RCC Oscillators according to the specified parameters * in the RCC_OscInitTypeDef structure. */ RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_MSI; RCC_OscInitStruct.MSIState = RCC_MSI_ON; RCC_OscInitStruct.MSICalibrationValue = RCC_MSICALIBRATION_DEFAULT; RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_6; RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE; if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) { Error_Handler(); } /** Initializes the CPU, AHB and APB buses clocks */ RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK |RCC_CLOCKTYPE_PCLK1; RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_MSI; RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1; RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2; if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK) { Error_Handler(); } } /** * @brief LPUART1 Initialization Function * @PAram None * @retval None */ static void MX_LPUART1_UART_Init(void) { /* USER CODE BEGIN LPUART1_Init 0 */ /* USER CODE END LPUART1_Init 0 */ /* USER CODE BEGIN LPUART1_Init 1 */ /* USER CODE END LPUART1_Init 1 */ hlpuart1.Instance = LPUART1; hlpuart1.Init.BaudRate = 115200; hlpuart1.Init.WordLength = UART_WORDLENGTH_8B; hlpuart1.Init.StopBits = UART_STOPBITS_1; hlpuart1.Init.Parity = UART_PARITY_NONE; hlpuart1.Init.Mode = UART_MODE_TX_RX; hlpuart1.Init.HwFlowCtl = UART_HWCONTROL_NONE; hlpuart1.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE; hlpuart1.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT; if (HAL_RS485Ex_Init(&hlpuart1, UART_DE_POLARITY_HIGH, 0, 0) != HAL_OK) { Error_Handler(); } if (HAL_UARTEx_SetTxFifoThreshold(&hlpuart1, UART_TXFIFO_THRESHOLD_1_8) != HAL_OK) { Error_Handler(); } if (HAL_UARTEx_SetRxFifoThreshold(&hlpuart1, UART_RXFIFO_THRESHOLD_1_8) != HAL_OK) { Error_Handler(); } if (HAL_UARTEx_DisableFifoMode(&hlpuart1) != HAL_OK) { Error_Handler(); } /* USER CODE BEGIN LPUART1_Init 2 */ /* USER CODE END LPUART1_Init 2 */ } /** * @brief USART3 Initialization Function * @PAram None * @retval None */ static void MX_USART3_UART_Init(void) { /* USER CODE BEGIN USART3_Init 0 */ /* USER CODE END USART3_Init 0 */ /* USER CODE BEGIN USART3_Init 1 */ /* USER CODE END USART3_Init 1 */ huart3.Instance = USART3; huart3.Init.BaudRate = 115200; huart3.Init.WordLength = UART_WORDLENGTH_8B; huart3.Init.StopBits = UART_STOPBITS_1; huart3.Init.Parity = UART_PARITY_NONE; huart3.Init.Mode = UART_MODE_TX_RX; huart3.Init.HwFlowCtl = UART_HWCONTROL_NONE; huart3.Init.OverSampling = UART_OVERSAMPLING_16; huart3.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE; huart3.Init.ClockPrescaler = UART_PRESCALER_DIV1; huart3.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT; if (HAL_UART_Init(&huart3) != HAL_OK) { Error_Handler(); } if (HAL_UARTEx_SetTxFifoThreshold(&huart3, UART_TXFIFO_THRESHOLD_1_8) != HAL_OK) { Error_Handler(); } if (HAL_UARTEx_SetRxFifoThreshold(&huart3, UART_RXFIFO_THRESHOLD_1_8) != HAL_OK) { Error_Handler(); } if (HAL_UARTEx_DisableFifoMode(&huart3) != HAL_OK) { Error_Handler(); } /* USER CODE BEGIN USART3_Init 2 */ /* USER CODE END USART3_Init 2 */ } /** * @brief GPIO Initialization Function * @PAram None * @retval None */ static void MX_GPIO_Init(void) { GPIO_InitTypeDef GPIO_InitStruct = {0}; /* USER CODE BEGIN MX_GPIO_Init_1 */ /* USER CODE END MX_GPIO_Init_1 */ /* GPIO Ports Clock Enable */ __HAL_RCC_GPIOC_CLK_ENABLE(); __HAL_RCC_GPIOA_CLK_ENABLE(); __HAL_RCC_GPIOB_CLK_ENABLE(); /*Configure GPIO pin Output Level */ HAL_GPIO_WritePin(data_enable_GPIO_Port, data_enable_Pin, GPIO_PIN_RESET); /*Configure GPIO pin : data_enable_Pin */ GPIO_InitStruct.Pin = data_enable_Pin; GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP; GPIO_InitStruct.Pull = GPIO_NOPULL; GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW; HAL_GPIO_Init(data_enable_GPIO_Port, &GPIO_InitStruct); /* USER CODE BEGIN MX_GPIO_Init_2 */ /* USER CODE END MX_GPIO_Init_2 */ } /* USER CODE BEGIN 4 */ /* USER CODE END 4 */ /** * @brief This function is executed in case of error occurrence. * @retval None */ void Error_Handler(void) { /* USER CODE BEGIN Error_Handler_Debug */ /* User can add his own implementation to report the HAL error return state */ __disable_irq(); while (1) { } /* USER CODE END Error_Handler_Debug */ } #ifdef USE_FULL_ASSERT /** * @brief Reports the name of the source file and the source line number * where the assert_param error has occurred. * @PAram file: pointer to the source file name * @PAram line: assert_param error line source number * @retval None */ void assert_failed(uint8_t *file, uint32_t line) { /* USER CODE BEGIN 6 */ /* User can add his own implementation to report the file name and line number, ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */ /* USER CODE END 6 */ } #endif /* USE_FULL_ASSERT */
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will u plz guide me how to work with it 

Pavel A.
Evangelist III

Several Modbus projects are on github, have a look.

https://github.com/urands/stModbus

https://github.com/alejoseb/Modbus-STM32-HAL-FreeRTOS

and more.

 

You didn't enable UART interrupt so HAL_UART_RxCpltCallback will never be called. 

Don't worry, I won't byte.
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