up

2025-12-13 14:37:44 +03:00
commit dce9b85a84
5 changed files with 507 additions and 0 deletions
--- a/.gitignore
+++ b/.gitignore
@@ -0,0 +1 @@
+modbus_constants.h
--- a/modbus.c
+++ b/modbus.c
@@ -0,0 +1,430 @@
+#include "modbus.h"
+#define TX_EN                       GPIO_WriteBit(RS485_GPIO, RS485_GPIO_Pin, Bit_SET);
+#define TX_DIS                      GPIO_WriteBit(RS485_GPIO, RS485_GPIO_Pin, Bit_RESET);
+#define MODBUS_LED_ON               GPIO_WriteBit(Modbus_LED, Modbus_LED_Pin, Bit_SET);
+#define MODBUS_LED_OFF              GPIO_WriteBit(Modbus_LED, Modbus_LED_Pin, Bit_RESET);
+
+static uint8_t buf_ptr = 0;
+static unsigned char rx_buf_ptr = 0;
+static unsigned char rx_buf[128];
+static unsigned char tx_buf[128];
+
+static uint16_t addr_buf_1 = 0, addr_buf_2 = 0;
+static uint16_t regs_to_read = 0;
+static uint16_t CRC16 = 0;
+static unsigned char crc_buf[300];
+static unsigned char modbus_id = 0;
+static uint16_t reg_wr_data = 0;
+static uint16_t modbus_reg_addr;
+
+
+static uint16_t holding_registers[MAX_HOLDING_REGISTERS];
+static uint16_t input_registers[MAX_INPUT_REGISTERS];
+
+static unsigned char rx_flag = 0;
+static unsigned char timer_state = 0;
+
+
+static uint16_t dev_id = DEFAULT_DEVICE_MODBUS_ID;
+const uint16_t com_dev_id = 247;
+
+static void (*ModbusUartSendByte)(USART_TypeDef*, unsigned char);
+static int32_t (*ModbusTcpSendByte)(uint8_t, unsigned char*, uint16_t);
+static void (*ModbusRIRPoll)(void);
+static void (*ModbusRHRPoll)(void);
+static void (*ModbusWSRPoll)(uint16_t, uint16_t);
+
+void modbus_connect_callback_send_byte(void (*s)(USART_TypeDef*, unsigned char)) {
+    ModbusUartSendByte = s;
+}
+
+void modbus_connect_callback_send_buf_tcp(int32_t (*s)(uint8_t, unsigned char*, uint16_t)) {
+    ModbusTcpSendByte = s;
+}
+
+void modbus_connect_callback_rir_poll(void (*s)(void)) {
+    ModbusRIRPoll = s;
+}
+
+void modbus_connect_callback_rhr_poll(void (*s)(void)) {
+    ModbusRHRPoll = s;
+}
+
+void modbus_connect_callback_wsr_poll(void (*s)(uint16_t, uint16_t)) {
+    ModbusWSRPoll = s;
+}
+
+static uint16_t modbus_CRC16(unsigned char buf[], uint16_t len)
+{
+    /// <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD> crc16
+
+    uint16_t crc = 0xFFFF;
+    //U8 crc_lsb, crc_msb;
+    for (uint16_t pos = 0; pos < len; pos++) {
+        crc ^= (uint16_t)buf[pos];          // XOR byte into least sig. byte of crc
+        for (int i = 8; i != 0; i--) {    // Loop over each bit
+            if ((crc & 0x0001) != 0) {      // If the LSB is set
+                crc >>= 1;                // Shift right and XOR 0xA001
+                crc ^= 0xA001;
+            }
+            else                          // Else LSB is not set
+                crc >>= 1;                  // Just shift right
+        }
+    }
+
+    // Note, this number has low and high bytes swapped, 
+    // so use it accordingly (or swap bytes)
+    // swapping bytes
+    crc = ((crc<<8)&0xff00)|((crc>>8)&0x00ff);
+
+    return crc;
+}
+
+void modbus_wsr_answer() {
+    crc_buf[0] = (modbus_id == dev_id) ? dev_id : com_dev_id;
+    crc_buf[1] = (unsigned char) MODBUS_WSR_CMD;
+    crc_buf[2] = (unsigned char) (modbus_reg_addr >> 8);
+    crc_buf[3] = (unsigned char) (modbus_reg_addr & 0xff);
+    crc_buf[4] = (unsigned char) (reg_wr_data >> 8);
+    crc_buf[5] = (unsigned char) (reg_wr_data & 0xff);
+    
+    CRC16 = modbus_CRC16(crc_buf, 6);
+    
+    switch(CURRENT_OPERATION_MODE) {
+	case 0:
+	    TX_EN;
+	    ModbusUartSendByte(Modbus_UART, (modbus_id == dev_id) ? dev_id : com_dev_id);
+	    ModbusUartSendByte(Modbus_UART, (unsigned char)MODBUS_WSR_CMD);
+	    ModbusUartSendByte(Modbus_UART, modbus_reg_addr >> 8);
+	    ModbusUartSendByte(Modbus_UART, modbus_reg_addr & 0xff);
+	    ModbusUartSendByte(Modbus_UART, reg_wr_data >> 8);
+	    ModbusUartSendByte(Modbus_UART, reg_wr_data & 0xff);
+    
+	    ModbusUartSendByte(Modbus_UART, CRC16 >> 8);
+	    ModbusUartSendByte(Modbus_UART, CRC16 & 0xff);
+	    TX_DIS;
+	break;
+	case 1:
+	    tx_buf[0] = (modbus_id == dev_id) ? dev_id : com_dev_id;
+	    tx_buf[1] = MODBUS_WSR_CMD;
+	    tx_buf[2] = modbus_reg_addr >> 8;
+	    tx_buf[3] = modbus_reg_addr & 0xff;
+	    tx_buf[4] = reg_wr_data >> 8;
+	    tx_buf[5] = reg_wr_data & 0xff;
+	    tx_buf[6] = CRC16 >> 8;
+	    tx_buf[7] = CRC16 & 0xff;
+
+	    ModbusTcpSendByte(DEFAULT_TCP_MODBUS_SOCKET, tx_buf, 8);
+	break;
+    }
+}
+
+void modbus_rir_answer() {
+    buf_ptr = 0;
+    addr_buf_1 = modbus_reg_addr;
+    addr_buf_2 = addr_buf_1;
+    
+    crc_buf[0] = (modbus_id == dev_id) ? dev_id : com_dev_id;
+    crc_buf[1] = MODBUS_RIR_CMD;
+    crc_buf[2] = regs_to_read * 2;
+    
+    unsigned char cnt = CRC_COUNT_OFFSET;
+    
+    for (int i = 0; i < regs_to_read; i++) {
+        crc_buf[cnt++] = (unsigned char)(input_registers[addr_buf_1] >> 8);
+        crc_buf[cnt++] = (unsigned char)(input_registers[addr_buf_1] & 0xff);
+        ++addr_buf_1;
+    }
+    
+    CRC16 = modbus_CRC16(crc_buf, regs_to_read * 2 + CRC_COUNT_OFFSET);
+    
+    switch(CURRENT_OPERATION_MODE) {
+	case 0:
+	    TX_EN;
+	    ModbusUartSendByte(Modbus_UART, (modbus_id == dev_id) ? dev_id : com_dev_id);
+	    ModbusUartSendByte(Modbus_UART, (unsigned char) MODBUS_RIR_CMD);
+	    ModbusUartSendByte(Modbus_UART, regs_to_read * 2);
+    
+	    for (int i = 0; i < regs_to_read; i++) {
+		ModbusUartSendByte(Modbus_UART, (unsigned char)(input_registers[addr_buf_2] >> 8));
+		ModbusUartSendByte(Modbus_UART, (unsigned char)(input_registers[addr_buf_2] & 0xff));
+		++addr_buf_2;
+	    }
+	    ModbusUartSendByte(Modbus_UART, (unsigned char)(CRC16 >> 8));
+	    ModbusUartSendByte(Modbus_UART, (unsigned char)(CRC16 & 0xff));
+	    TX_DIS;
+	break;
+	case 1:
+	    tx_buf[buf_ptr++] = (modbus_id == dev_id) ? dev_id : com_dev_id;
+	    tx_buf[buf_ptr++] = (unsigned char) MODBUS_RIR_CMD;
+	    tx_buf[buf_ptr++] = regs_to_read * 2;
+
+	    for (int i = 0; i < regs_to_read; i++) {
+		tx_buf[buf_ptr++] = (unsigned char)(input_registers[addr_buf_2] >> 8);
+		tx_buf[buf_ptr++] = (unsigned char)(input_registers[addr_buf_2] & 0xff);
+		++addr_buf_2;
+	    }
+	    tx_buf[buf_ptr++] = CRC16 >> 8;
+	    tx_buf[buf_ptr++] = CRC16 & 0xff;
+	    ModbusTcpSendByte(DEFAULT_TCP_MODBUS_SOCKET, tx_buf, buf_ptr);
+	break;
+    }
+
+}
+
+void modbus_rhr_answer() {
+    buf_ptr = 0;
+    addr_buf_1 = modbus_reg_addr;
+    addr_buf_2 = addr_buf_1;
+    
+    crc_buf[0] = (modbus_id == dev_id) ? dev_id : com_dev_id;
+    crc_buf[1] = MODBUS_RHR_CMD;
+    crc_buf[2] = regs_to_read * 2;
+    
+    unsigned char cnt = CRC_COUNT_OFFSET;
+    
+    for (int i = 0; i < regs_to_read; i++) {
+        crc_buf[cnt++] = (unsigned char)(holding_registers[addr_buf_1] >> 8);
+        crc_buf[cnt++] = (unsigned char)(holding_registers[addr_buf_1] & 0xff);
+        ++addr_buf_1;
+    }
+    
+    CRC16 = modbus_CRC16(crc_buf, regs_to_read * 2 + CRC_COUNT_OFFSET);
+    
+    switch(CURRENT_OPERATION_MODE) {
+	case 0:
+	    TX_EN;
+	    ModbusUartSendByte(Modbus_UART, (modbus_id == dev_id) ? dev_id : com_dev_id);
+	    ModbusUartSendByte(Modbus_UART, (unsigned char) MODBUS_RHR_CMD);
+	    ModbusUartSendByte(Modbus_UART, regs_to_read * 2);
+    
+	    for (int i = 0; i < regs_to_read; i++) {
+		ModbusUartSendByte(Modbus_UART, (unsigned char)(holding_registers[addr_buf_2] >> 8));
+		ModbusUartSendByte(Modbus_UART, (unsigned char)(holding_registers[addr_buf_2] & 0xff));
+		++addr_buf_2;
+	    }
+	    ModbusUartSendByte(Modbus_UART, (unsigned char)(CRC16 >> 8));
+	    ModbusUartSendByte(Modbus_UART, (unsigned char)(CRC16 & 0xff));
+	    TX_DIS;
+	break;
+	case 1:
+            tx_buf[buf_ptr++] = (modbus_id == dev_id) ? dev_id : com_dev_id;
+            tx_buf[buf_ptr++] = (unsigned char) MODBUS_RHR_CMD;
+            tx_buf[buf_ptr++] = regs_to_read * 2;
+
+            for (int i = 0; i < regs_to_read; i++) {
+                tx_buf[buf_ptr++] = (unsigned char)(holding_registers[addr_buf_2] >> 8);
+                tx_buf[buf_ptr++] = (unsigned char)(holding_registers[addr_buf_2] & 0xff);
+                ++addr_buf_2;
+            }
+            tx_buf[buf_ptr++] = CRC16 >> 8;
+            tx_buf[buf_ptr++] = CRC16 & 0xff;
+            ModbusTcpSendByte(DEFAULT_TCP_MODBUS_SOCKET, tx_buf, buf_ptr);
+
+	break;
+    }
+}
+
+static unsigned char modbus_rx_CRC_check(unsigned char modbus_cmd) {
+    /// <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> CRC <20><><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> <20> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> <20> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>  
+    uint16_t CRC16_calc = 0;  // <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> <20><><EFBFBD><EFBFBD><EFBFBD>
+    unsigned char ans = 0;
+
+    modbus_reg_addr = (uint16_t)((rx_buf[2] << 8) | rx_buf[3]); // get starting reg addr
+
+    crc_buf[0] = (modbus_id == dev_id) ? dev_id : com_dev_id;
+    crc_buf[2] = (unsigned char)(modbus_reg_addr >> 8);
+    crc_buf[3] = (unsigned char)(modbus_reg_addr & 0x00ff);
+
+
+    switch(modbus_cmd) {
+        case MODBUS_WSR_CMD:
+            reg_wr_data	= (rx_buf[4] << 8) | rx_buf[5]; // get data to write into reg
+
+            crc_buf[1] = (unsigned char) MODBUS_WSR_CMD;
+            crc_buf[4] = (unsigned char)(reg_wr_data >> 8);
+            crc_buf[5] = (unsigned char)(reg_wr_data & 0x00ff);
+        break;
+        //----
+        case MODBUS_RHR_CMD:
+            regs_to_read = (rx_buf[4] << 8) | rx_buf[5]; // get number of regs to read
+
+            crc_buf[1] = (unsigned char) MODBUS_RHR_CMD;
+            crc_buf[4] = (unsigned char)(regs_to_read >> 8);
+            crc_buf[5] = (unsigned char)(regs_to_read & 0x00ff);
+        break;
+        //----
+        case MODBUS_RIR_CMD:
+            regs_to_read = (rx_buf[4] << 8) | rx_buf[5]; // get number of regs to read
+
+            crc_buf[1] = (unsigned char) MODBUS_RIR_CMD;
+            crc_buf[4] = (unsigned char)(regs_to_read >> 8);
+            crc_buf[5] = (unsigned char)(regs_to_read & 0x00ff);
+        break;
+        //----
+        default: break;
+    }
+
+    CRC16 = (rx_buf[6] << 8) | rx_buf[7]; // get CRC16 from rx msg
+    CRC16_calc = modbus_CRC16(crc_buf,6); // calc CRC16  
+
+    if(CRC16_calc == CRC16) 
+        ans = modbus_cmd;
+
+    return ans;
+}
+
+unsigned char modbus_get_poll(void)  
+{
+    /// update modbus regs and vars, send answer to master
+    unsigned char rx_cmd_code = 0;        // ??? ??????????? ???????rx_cmd_code = 0;
+    // state 1 and 2, transmit end, rx buf has > 7 bytes ?
+    //
+    if ( rx_flag == 1 ) {
+        if( rx_buf_ptr > 7 ) { 
+            modbus_id = rx_buf[0];      // get device ID from master msg
+            
+            if((modbus_id == dev_id) || (modbus_id == com_dev_id)) {
+                switch(rx_buf[1]) {   
+                    case MODBUS_RHR_CMD:                // ???? ??????? - ?????? R/W ?????????
+                        if(modbus_rx_CRC_check(MODBUS_RHR_CMD) == MODBUS_RHR_CMD) {
+                            rx_cmd_code = MODBUS_RHR_CMD;
+                        }
+                    break;
+                    ////-------------------------------------------------------------------
+                    case MODBUS_WSR_CMD:                // ???? ??????? - ?????? Read-only ?????????
+                        if(modbus_rx_CRC_check(MODBUS_WSR_CMD) == MODBUS_WSR_CMD) {
+                            rx_cmd_code = MODBUS_WSR_CMD;
+                            holding_reg_write(modbus_reg_addr, reg_wr_data); // !!!! 
+                        }
+                    break;
+                    ////-------------------------------------------------------------------
+                    case MODBUS_RIR_CMD: 
+                        if(modbus_rx_CRC_check(MODBUS_RIR_CMD) == MODBUS_RIR_CMD) {
+                            rx_cmd_code = MODBUS_RIR_CMD;
+                        }
+                    break;
+                } // switch(rx_buf[1])
+                modbus_reset();
+            } else {
+                modbus_reset();
+            }// if dev_id
+        } else { modbus_reset(); } //  if(rx_buf_pos > 7)
+    }
+
+    return rx_cmd_code; 
+}
+
+void modbus_reset(void)
+{ 
+    for(int i = 0; i < 128; i++) 
+        rx_buf[i] = 0;
+
+    rx_buf_ptr = 0;
+    rx_flag = 0;
+}
+
+void holding_reg_write(uint16_t red_addr, uint16_t value) {
+    holding_registers[red_addr] = value;
+}
+
+void holding_reg_read(uint16_t red_addr, uint16_t *usr_var_ptr) {
+    *usr_var_ptr = holding_registers[red_addr];
+}
+
+void input_reg_read(uint16_t red_addr, uint16_t *usr_var_ptr) {
+    *usr_var_ptr = input_registers[red_addr];
+}
+  
+void input_reg_write(uint16_t reg_addr, uint16_t value) {
+    input_registers[reg_addr] = value;
+}
+
+uint16_t get_wr_reg_addr(void) {
+    return modbus_reg_addr;
+}
+
+uint16_t get_wr_reg_val(void) {
+    return reg_wr_data;
+}
+
+unsigned char get_modbus_id(void) {
+    return dev_id;
+}
+
+void set_modbus_id(unsigned char newID)
+{
+    dev_id = newID;
+    modbus_reset();
+}
+
+static uint16_t RegisterAddr  = 0;
+static uint16_t RegisterValue = 0;
+
+void modbus_poll(void) {
+    uint8_t mb_get_poll = modbus_get_poll();
+    switch(mb_get_poll) { 
+        //////////////////////////// READING INPUTS  ////////////////////////// 
+        case MODBUS_RIR_CMD:
+            MODBUS_LED_ON;
+            ModbusRIRPoll();
+            modbus_rir_answer();
+            MODBUS_LED_OFF;
+        break;
+        //////////////////////////// READING HOLDING ////////////////////////// 
+        case MODBUS_RHR_CMD:
+            MODBUS_LED_ON;
+            ModbusRHRPoll();
+	    modbus_rhr_answer(); 
+            MODBUS_LED_OFF;
+        break;
+        //////////////////////////// WRITING HOLDING ////////////////////////// 
+        case MODBUS_WSR_CMD:
+            MODBUS_LED_ON;
+            modbus_wsr_answer();
+        
+            RegisterAddr  = get_wr_reg_addr();  // get address
+            RegisterValue = get_wr_reg_val();   // get the new value
+
+            ModbusWSRPoll(RegisterAddr, RegisterValue);
+            MODBUS_LED_OFF;			// LED toggle
+       break;
+    } // switch
+}
+//======================= UART HANDLERS =========================//
+void Modbus_UART_IRQHandler(void) {
+    if (USART_GetITStatus(Modbus_UART, USART_IT_RXNE) != RESET) {
+        while(USART_GetFlagStatus(Modbus_UART,USART_FLAG_RXNE) == RESET) {}
+        if (rx_buf_ptr < 128) {
+            rx_buf[rx_buf_ptr++] = (unsigned char)Modbus_UART -> DR;
+        } else {
+            Modbus_UART -> DR;
+        }
+        USART_ClearITPendingBit(Modbus_UART, USART_IT_RXNE);
+        
+        if (timer_state == 0) {
+            timer_state = 1;
+            Modbus_TIM -> CNT = 0;
+            TIM_Cmd(Modbus_TIM, ENABLE);
+        }
+    }
+}
+
+void Modbus_TIM_IRQHandler(void) {
+    if (TIM_GetITStatus(Modbus_TIM, TIM_IT_Update) != RESET)
+        TIM_ClearITPendingBit(Modbus_TIM, TIM_IT_Update);
+    
+    TIM_Cmd(Modbus_TIM, DISABLE);
+    timer_state = 0;
+    rx_flag = 1;
+}
+
+
+//======================== TCP HANDLERS ========================//
+void Modbus_TCP_Handler(unsigned char* buf, uint8_t size) {
+    for (rx_buf_ptr = 0; rx_buf_ptr < size; rx_buf_ptr++) {
+	rx_buf[rx_buf_ptr] = buf[rx_buf_ptr];
+    }
+
+    rx_flag = 1;
+}
--- a/modbus.h
+++ b/modbus.h
@@ -0,0 +1,38 @@
+#ifndef _MODBUS_H
+#define _MODBUS_H
+
+// Includes
+#include "modbus_constants.h"
+#include "stdlib.h"
+
+void    Modbus_TCP_Handler(unsigned char*, uint8_t);
+static unsigned char modbus_rx_buf[128];
+
+#define CRC_COUNT_OFFSET            3
+
+#define MODBUS_RHR_CMD              (unsigned char)0x03
+#define MODBUS_RIR_CMD              (unsigned char)0x04
+#define MODBUS_WSR_CMD              (unsigned char)0x06
+
+void modbus_wsr_answer(void);
+void modbus_rhr_answer(void);
+unsigned char modbus_get_poll(void);
+void holding_reg_write(uint16_t, uint16_t);
+void holding_reg_read(uint16_t, uint16_t*);
+void input_reg_write(uint16_t, uint16_t);
+void input_reg_read(uint16_t, uint16_t*);
+uint16_t get_wr_reg_addr(void);
+uint16_t get_wr_reg_val(void);
+unsigned char get_modbus_id(void);
+void set_modbus_id(unsigned char);
+
+
+void modbus_connect_callback_send_byte(void (*s)(USART_TypeDef*, unsigned char));
+void modbus_connect_callback_send_buf_tcp(int32_t (*s)(uint8_t, unsigned char*, uint16_t));
+void modbus_connect_callback_rir_poll(void (*s)(void));
+void modbus_connect_callback_rhr_poll(void (*s)(void));
+void modbus_connect_callback_wsr_poll(void (*s)(uint16_t, uint16_t));
+void modbus_poll(void);
+void modbus_reset(void);
+
+#endif
--- a/modbus_constants_example.h
+++ b/modbus_constants_example.h
@@ -0,0 +1,28 @@
+#ifndef _MODBUS_CONSTANTS_H
+#define _MODBUS_CONSTANTS_H
+
+#define MAX_HOLDING_REGISTERS               300
+#define MAX_INPUT_REGISTERS                 300
+
+// MCU Includes
+
+#include "stm32f4xx.h"
+#include "stm32f4xx_usart.h"
+
+
+// Needed Constants
+
+#define DEFAULT_DEVICE_MODBUS_ID    1
+#define DEFAULT_TCP_MODBUS_SOCKET   0
+#define CURRENT_OPERATION_MODE      1 // UART - 0, TCP - 1
+
+#define RS485_GPIO                  GPIOB
+#define RS485_GPIO_Pin              GPIO_Pin_6
+#define Modbus_UART                 USART2
+#define Modbus_TIM                  TIM2
+#define Modbus_UART_IRQHandler      USART2_IRQHandler
+#define Modbus_TIM_IRQHandler       TIM2_IRQHandler
+#define Modbus_LED                  GPIOD
+#define Modbus_LED_Pin              GPIO_Pin_2
+
+#endif
--- a/readme.txt
+++ b/readme.txt
@@ -0,0 +1,10 @@
+Modbus Library for slave devices based on STM32 MCU (v5)
+Supports Modbus RTU and Modbus RTU over TCP modes.
+
+Original library was written by @ponkin_dmitry
+
+Single header library which allow you to connect your devices using Modbus protocol. 
+Main configuration takes place in `modbus_constants.h` file.
+
+Buffer sizes needs to be set via definitions `MAX_HOLDING_REGISTERS` and `MAX_INPUT_REGISTERS`.
+Create your `modbus_constants.h` header file from example which is in the current repo.