Question
stm32 modbus
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);
}
}
