modbus tcp

#include <stdio.h> #include <string.h> #include <unistd.h> #include "tcp.h" #include "modbus_tcp.h" #define MODBUS_TCP_PORT 502 #define LEN_NORMAL 6 #define READ_COIL_FC 0x01 #define READ_DISCRETE_INPUT_FC 0x02 #define READ_INPUT_REGISTER_FC 0x04 #define WRITE_COIL_FC 0x05 #define WRITE_SINGLE_REGISTER_FC 0x06 #define MAX_REQUEST_PACKET_LEN 20 #define MAX_RESPONSE_PACKET_LEN 300 #define MAX_RESPONSE_RESULT_LEN 300 #define MODBUS_TCP_DEFAULT_TIME_OUT 1000 #define OK 0 #define INVALID_INPUT 1 #define NET_ERR 2 #define ILLEGAL_FUNCTION 3 #define ILLEGAL_DATA_ADDR 4 #define ILLEGAL_DATA_VALUE 5 #define ILLEGAL_RESPONSE_LENGTH 6 #define ACKNOWLEDGE 7 #define SLAVE_DEVICE_BUSY 8 #define DENIED 9 #define MEMORY_PARITY_ERR 10 #define GATEWAY_PATH_UNABLE 11 #define GATEWAY_TARGET_DEV_FAIL 12 #define RESPONSE_ABNORMAL 13 #define TRUE 1 #define FAUSE 0 #define DEBUG 1 #if DEBUG #define dprintf(format, args...) printf(format, ##args) #else #define dprintf(format, args...) #endif #pragma pack(1) typedef struct { uint8_t invalid[5]; uint8_t len; uint8_t unit; uint8_t fc; } modbus_tcp_header_t; static int read_common_modbus_tcp(int sockfd, uint8_t unit, \ uint8_t fc, uint16_t start_addr, uint16_t count, \ uint8_t *result, uint16_t *result_size); static int get_request_packet_common(modbus_tcp_header_t modbus_header, \ uint16_t start_addr, uint16_t var, uint8_t *packet); static int get_response_result_common(int sockfd, \ modbus_tcp_header_t modbus_header, uint16_t count, \ uint8_t *result, uint16_t *result_size); static int get_response_result_read_input_register(int sockfd, \ modbus_tcp_header_t modbus_header, uint16_t count, \ uint16_t *result, uint16_t *result_size); static int get_response_packet(int sockfd, \ modbus_tcp_header_t modbus_header, \ uint8_t *packet, uint16_t *packet_size); static int get_response_result_write_coil(int sockfd, \ modbus_tcp_header_t modbus_header, \ uint16_t *address, uint16_t *state); static int get_response_result_write_single_register(int sockfd, \ modbus_tcp_header_t modbus_header, \ uint16_t *address, uint16_t *value); /********************************************************* init_modbus_tcp() Init the tcp modbus with the ip and get the socket description. ***********************************************************/ int init_modbus_tcp(const char *ip, int *sockfd) { if ((ip == NULL) || (sockfd == NULL)) { return INVALID_INPUT; } int rc; *sockfd = inittcpsock(); if (*sockfd < 0) { return NET_ERR; } rc = clientconn(*sockfd, ip, MODBUS_TCP_PORT); if (rc < 0) { return NET_ERR; } return OK; } /********************************************************* read_coil_modbus_tcp() Read the boolean status of coils and set the array elements in the result to TRUE or FALSE. ***********************************************************/ int read_coil_modbus_tcp(int sockfd, uint8_t unit, \ uint16_t start_addr, uint16_t count, uint8_t *result, \ uint16_t *result_size) { int rc = read_common_modbus_tcp(sockfd, unit, \ READ_COIL_FC, start_addr, count, result, result_size); return rc; } /********************************************************* read_discrete_input_modbus_tcp() Read the boolean status of discrete input and set the array elements in the result to TRUE or FALSE. ***********************************************************/ int read_discrete_input_modbus_tcp(int sockfd, uint8_t unit, \ uint16_t start_addr, uint16_t count, uint8_t *result, \ uint16_t *result_size) { int rc = read_common_modbus_tcp(sockfd, unit, \ READ_DISCRETE_INPUT_FC, start_addr, count, result, result_size); return rc; } /********************************************************* read_input_register_modbus_tcp() Read the input registers and put the data into an array. ***********************************************************/ int read_input_register_modbus_tcp(int sockfd, uint8_t unit, \ uint16_t start_addr, uint16_t count, uint16_t *result, \ uint16_t *result_size) { if (sockfd < 0) { return NET_ERR; } if ((result == NULL) || (result_size == NULL)) { return INVALID_INPUT; } int rc; int len; uint8_t packet[MAX_REQUEST_PACKET_LEN]; modbus_tcp_header_t modbus_header; memset(&modbus_header, 0, sizeof(modbus_header)); modbus_header.len = LEN_NORMAL; modbus_header.unit = unit; modbus_header.fc = READ_INPUT_REGISTER_FC; len = get_request_packet_common(modbus_header, start_addr, \ count, packet); #if DEBUG int i; for (i = 0; i < len; i++) { dprintf("0x%x ", packet[i]); } dprintf("\n"); #endif rc = clientwrite(sockfd, packet, len); if (rc < 0) { return NET_ERR; } rc = get_response_result_read_input_register(sockfd, \ modbus_header, count, result, result_size); if (rc != OK) { return rc; } return OK; } /********************************************************* read_ndata_from_input_register_modbus_tcp() Read the float data from input registers and put the data into an array. ***********************************************************/ int read_ndata_from_input_register_modbus_tcp(int sockfd, \ uint8_t unit, uint16_t start_addr, uint16_t count, \ uint32_t *result, uint16_t *result_size) { int rc; int i, j = 0; uint16_t tmp_result[MAX_RESPONSE_RESULT_LEN]; uint16_t tmp_result_size; rc = read_input_register_modbus_tcp(sockfd, unit, \ start_addr, 2*count, tmp_result, &tmp_result_size); if (rc != OK) { return rc; } *result_size = tmp_result_size / 2; for (i = 0; i < tmp_result_size; i += 2, j++) { result[j] = tmp_result[i + 1]; result[j] = (result[j] << 16) + tmp_result[i]; } return OK; } /********************************************************* write_coil_modbus_tcp() Set the coil state on or off. ***********************************************************/ int write_coil_modbus_tcp(int sockfd, uint8_t unit, \ uint16_t start_addr, uint16_t state) { if (sockfd < 0) { return NET_ERR; } int rc; int len; uint8_t packet[MAX_REQUEST_PACKET_LEN]; modbus_tcp_header_t modbus_header; uint16_t state2 = state << 8; uint16_t address; uint16_t value; memset(&modbus_header, 0, sizeof(modbus_header)); modbus_header.len = LEN_NORMAL; modbus_header.unit = unit; modbus_header.fc = WRITE_COIL_FC; len = get_request_packet_common(modbus_header, start_addr, \ state2, packet); #if DEBUG int i; for (i = 0; i < len; i++) { dprintf("0x%x ", packet[i]); } dprintf("\n"); #endif rc = clientwrite(sockfd, packet, len); if (rc < 0) { return NET_ERR; } rc = get_response_result_write_coil(sockfd, modbus_header, \ &address, &value); if (rc != OK) { return rc; } dprintf("address = 0x%x\n", address); dprintf("state = 0x%x\n", value); return OK; } /********************************************************* write_single_register_modbus_tcp() Set the single register with the value. ***********************************************************/ int write_single_register_mod