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Added feature RTU over TCP #260

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24 changes: 18 additions & 6 deletions src/modbus-rtu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -102,8 +102,12 @@ static int _modbus_set_slave(modbus_t *ctx, int slave)
return 0;
}


int _modbus_rtu_build_request_basis(modbus_t *ctx, int function,
int addr, int nb,
uint8_t *req);
/* Builds a RTU request header */
static int _modbus_rtu_build_request_basis(modbus_t *ctx, int function,
int _modbus_rtu_build_request_basis(modbus_t *ctx, int function,
int addr, int nb,
uint8_t *req)
{
Expand All @@ -118,8 +122,9 @@ static int _modbus_rtu_build_request_basis(modbus_t *ctx, int function,
return _MODBUS_RTU_PRESET_REQ_LENGTH;
}

int _modbus_rtu_build_response_basis(sft_t *sft, uint8_t *rsp);
/* Builds a RTU response header */
static int _modbus_rtu_build_response_basis(sft_t *sft, uint8_t *rsp)
int _modbus_rtu_build_response_basis(sft_t *sft, uint8_t *rsp)
{
/* In this case, the slave is certainly valid because a check is already
* done in _modbus_rtu_listen */
Expand All @@ -129,7 +134,10 @@ static int _modbus_rtu_build_response_basis(sft_t *sft, uint8_t *rsp)
return _MODBUS_RTU_PRESET_RSP_LENGTH;
}

static uint16_t crc16(uint8_t *buffer, uint16_t buffer_length)

uint16_t crc16(uint8_t *buffer, uint16_t buffer_length);

uint16_t crc16(uint8_t *buffer, uint16_t buffer_length)
{
uint8_t crc_hi = 0xFF; /* high CRC byte initialized */
uint8_t crc_lo = 0xFF; /* low CRC byte initialized */
Expand All @@ -145,14 +153,16 @@ static uint16_t crc16(uint8_t *buffer, uint16_t buffer_length)
return (crc_hi << 8 | crc_lo);
}

static int _modbus_rtu_prepare_response_tid(const uint8_t *req, int *req_length)
int _modbus_rtu_prepare_response_tid(const uint8_t *req, int *req_length);
int _modbus_rtu_prepare_response_tid(const uint8_t *req, int *req_length)
{
(*req_length) -= _MODBUS_RTU_CHECKSUM_LENGTH;
/* No TID */
return 0;
}

static int _modbus_rtu_send_msg_pre(uint8_t *req, int req_length)
int _modbus_rtu_send_msg_pre(uint8_t *req, int req_length);
int _modbus_rtu_send_msg_pre(uint8_t *req, int req_length)
{
uint16_t crc = crc16(req, req_length);
req[req_length++] = crc >> 8;
Expand Down Expand Up @@ -352,10 +362,12 @@ static int _modbus_rtu_pre_check_confirmation(modbus_t *ctx, const uint8_t *req,
}
}

int _modbus_rtu_check_integrity(modbus_t *ctx, uint8_t *msg,
const int msg_length);
/* The check_crc16 function shall return 0 is the message is ignored and the
message length if the CRC is valid. Otherwise it shall return -1 and set
errno to EMBADCRC. */
static int _modbus_rtu_check_integrity(modbus_t *ctx, uint8_t *msg,
int _modbus_rtu_check_integrity(modbus_t *ctx, uint8_t *msg,
const int msg_length)
{
uint16_t crc_calculated;
Expand Down
160 changes: 156 additions & 4 deletions src/modbus-tcp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -169,7 +169,8 @@ static int _modbus_tcp_receive(modbus_t *ctx, uint8_t *req) {
return _modbus_receive_msg(ctx, req, MSG_INDICATION);
}

static ssize_t _modbus_tcp_recv(modbus_t *ctx, uint8_t *rsp, int rsp_length) {
ssize_t _modbus_tcp_recv(modbus_t *ctx, uint8_t *rsp, int rsp_length);
ssize_t _modbus_tcp_recv(modbus_t *ctx, uint8_t *rsp, int rsp_length) {
return recv(ctx->s, (char *)rsp, rsp_length, 0);
}

Expand Down Expand Up @@ -292,8 +293,9 @@ static int _connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen,
return rc;
}

int _modbus_tcp_connect(modbus_t *ctx);
/* Establishes a modbus TCP connection with a Modbus server. */
static int _modbus_tcp_connect(modbus_t *ctx)
int _modbus_tcp_connect(modbus_t *ctx)
{
int rc;
/* Specialized version of sockaddr for Internet socket address (same size) */
Expand Down Expand Up @@ -423,7 +425,8 @@ static int _modbus_tcp_pi_connect(modbus_t *ctx)
}

/* Closes the network connection and socket in TCP mode */
static void _modbus_tcp_close(modbus_t *ctx)
void _modbus_tcp_close(modbus_t *ctx);
void _modbus_tcp_close(modbus_t *ctx)
{
if (ctx->s != -1) {
shutdown(ctx->s, SHUT_RDWR);
Expand All @@ -432,7 +435,8 @@ static void _modbus_tcp_close(modbus_t *ctx)
}
}

static int _modbus_tcp_flush(modbus_t *ctx)
static int _modbus_tcp_flush(modbus_t *ctx);
int _modbus_tcp_flush(modbus_t *ctx)
{
int rc;
int rc_sum = 0;
Expand Down Expand Up @@ -751,6 +755,85 @@ const modbus_backend_t _modbus_tcp_backend = {
};







int _modbus_rtu_build_request_basis(modbus_t *ctx, int function,
int addr, int nb,
uint8_t *req);
int _modbus_rtu_build_response_basis(sft_t *sft, uint8_t *rsp);
int _modbus_rtu_prepare_response_tid(const uint8_t *req, int *req_length);
int _modbus_rtu_send_msg_pre(uint8_t *req, int req_length);
int _modbus_rtu_check_integrity(modbus_t *ctx, uint8_t *msg,
const int msg_length);
int _modbus_rtu_filter_request(modbus_t *ctx, int slave);
uint16_t crc16(uint8_t *buffer, uint16_t buffer_length);
int _modbus_rtutcp_check_integrity(modbus_t *ctx, uint8_t *msg,
const int msg_length);

/* The check_crc16 function shall return the message length if the CRC is
valid. Otherwise it shall return -1 and set errno to EMBADCRC. */
int _modbus_rtutcp_check_integrity(modbus_t *ctx, uint8_t *msg,
const int msg_length)
{
uint16_t crc_calculated;
uint16_t crc_received;

crc_calculated = crc16(msg, msg_length - 2);
crc_received = (msg[msg_length - 2] << 8) | msg[msg_length - 1];

/* Check CRC of msg */
if (crc_calculated == crc_received) {
return msg_length;
} else {
if (ctx->debug) {
fprintf(stderr, "ERROR CRC received %0X != CRC calculated %0X\n",
crc_received, crc_calculated);
}
if (ctx->error_recovery & MODBUS_ERROR_RECOVERY_PROTOCOL) {
_modbus_tcp_flush(ctx);
}
errno = EMBBADCRC;
return -1;
}
}



#define MODBUS_RTU_MAX_ADU_LENGTH 256
#define _MODBUS_RTU_CHECKSUM_LENGTH 2
#define _MODBUS_RTU_HEADER_LENGTH 1

const modbus_backend_t _modbus_rtutcp_backend = {
_MODBUS_BACKEND_TYPE_TCP,
_MODBUS_RTU_HEADER_LENGTH,
_MODBUS_RTU_CHECKSUM_LENGTH,
MODBUS_RTU_MAX_ADU_LENGTH,
_modbus_set_slave,
_modbus_rtu_build_request_basis,
_modbus_rtu_build_response_basis,
_modbus_rtu_prepare_response_tid,
_modbus_rtu_send_msg_pre,
_modbus_tcp_send,
_modbus_tcp_receive,
_modbus_tcp_recv,
_modbus_rtu_check_integrity,
NULL,
_modbus_tcp_connect,
_modbus_tcp_close,
_modbus_tcp_flush,
_modbus_tcp_select,
_modbus_tcp_free
};







const modbus_backend_t _modbus_tcp_pi_backend = {
_MODBUS_BACKEND_TYPE_TCP,
_MODBUS_TCP_HEADER_LENGTH,
Expand Down Expand Up @@ -830,6 +913,75 @@ modbus_t* modbus_new_tcp(const char *ip, int port)
}








modbus_t* modbus_new_rtutcp(const char *ip, int port)
{
modbus_t *ctx;
modbus_tcp_t *ctx_tcp;
size_t dest_size;
size_t ret_size;

#if defined(OS_BSD)
/* MSG_NOSIGNAL is unsupported on *BSD so we install an ignore
handler for SIGPIPE. */
struct sigaction sa;

sa.sa_handler = SIG_IGN;
if (sigaction(SIGPIPE, &sa, NULL) < 0) {
/* The debug flag can't be set here... */
fprintf(stderr, "Coud not install SIGPIPE handler.\n");
return NULL;
}
#endif

ctx = (modbus_t *) malloc(sizeof(modbus_t));
_modbus_init_common(ctx);

/* Could be changed after to reach a remote serial Modbus device */
ctx->slave = MODBUS_TCP_SLAVE;

ctx->backend = &(_modbus_rtutcp_backend);

ctx->backend_data = (modbus_tcp_t *) malloc(sizeof(modbus_tcp_t));
ctx_tcp = (modbus_tcp_t *)ctx->backend_data;

dest_size = sizeof(char) * 16;
ret_size = strlcpy(ctx_tcp->ip, ip, dest_size);
if (ret_size == 0) {
fprintf(stderr, "The IP string is empty\n");
modbus_free(ctx);
errno = EINVAL;
return NULL;
}

if (ret_size >= dest_size) {
fprintf(stderr, "The IP string has been truncated\n");
modbus_free(ctx);
errno = EINVAL;
return NULL;
}

ctx_tcp->port = port;

return ctx;
}












modbus_t* modbus_new_tcp_pi(const char *node, const char *service)
{
modbus_t *ctx;
Expand Down
1 change: 1 addition & 0 deletions src/modbus-tcp.h
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,7 @@ MODBUS_BEGIN_DECLS
#define MODBUS_TCP_MAX_ADU_LENGTH 260

MODBUS_API modbus_t* modbus_new_tcp(const char *ip_address, int port);
MODBUS_API modbus_t* modbus_new_rtutcp(const char *ip, int port);
MODBUS_API int modbus_tcp_listen(modbus_t *ctx, int nb_connection);
MODBUS_API int modbus_tcp_accept(modbus_t *ctx, int *s);

Expand Down