/*
* Copyright (c) 2001,2016 Mario de Sousa (msousa@fe.up.pt)
*
* This file is part of the Modbus library for Beremiz and matiec.
*
* This Modbus library is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
* General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this Modbus library. If not, see <http://www.gnu.org/licenses/>.
*
* This code is made available on the understanding that it will not be
* used in safety-critical situations without a full and competent review.
*/
/* mb_slave.c */
#include <fcntl.h> /* File control definitions */
#include <stdio.h> /* Standard input/output */
#include <string.h>
#include <stdlib.h>
#include <termio.h> /* POSIX terminal control definitions */
#include <sys/time.h> /* Time structures for select() */
#include <unistd.h> /* POSIX Symbolic Constants */
#include <errno.h> /* Error definitions */
#include <netinet/in.h> /* required for htons() and ntohs() */
#include "mb_layer1.h"
#include "mb_slave.h"
#include "mb_slave_private.h"
/* #define DEBUG */ /* uncomment to see the data sent and received */
#define modbus_write fptr_[layer1_fin].modbus_write
#define modbus_read fptr_[layer1_fin].modbus_read
#define modbus_init fptr_[layer1_fin].modbus_init
#define modbus_done fptr_[layer1_fin].modbus_done
#define modbus_connect fptr_[layer1_fin].modbus_connect
#define modbus_listen fptr_[layer1_fin].modbus_listen
#define modbus_close fptr_[layer1_fin].modbus_close
#define modbus_silence_init fptr_[layer1_fin].modbus_silence_init
#define modbus_get_min_timeout fptr_[layer1_fin].modbus_get_min_timeout
/* the lower two bits of ttyfd are used to store the index to layer1 function pointers */
/* layer1_fin index to fptr_[] is in lowest 2 bits of fd */
#define get_ttyfd() int layer1_fin = fd & 3; int ttyfd = fd / 4;\
if (fd < 0) {ttyfd = fd; layer1_fin = 0; /* use modbusTCP */}
/******************************************/
/******************************************/
/** **/
/** Global Variables... **/
/** **/
/******************************************/
/******************************************/
/* The layer 1 (RTU, ASCII, TCP) implementations will be adding some
* header and tail bytes (e.g. CRC) to the packet we build here. Since
* layer1 will re-use the same buffer allocated in this slave layer
* (so as not to continuosly copy the same info from buffer to buffer),
* we need to allocate more bytes than those strictly required for this
* slave layer. Therefore, the extra_bytes parameter.
*
* Note that we add one more extra byte to the response buffer.
* This is because some response packets will not be starting off
* at byte 0, but rather at byte 1 of the buffer. This is in order
* to guarantee that the data that is sent on the buffer is aligned
* on even bytes (the 16 bit words!). This will allow the application
* (layer above the one implemented in this file - i.e. the callback
* functions) to reference this memory as an u16 *, without producing
* 'bus error' messages in some embedded devices that do not allow
* acessing u16 on odd numbered addresses.
*/
static int buff_extra_bytes_;
#define RESP_BUFFER_SIZE (MAX_L2_FRAME_LENGTH + buff_extra_bytes_ + 1)
/******************************************/
/******************************************/
/** **/
/** Local Utility functions... **/
/** **/
/******************************************/
/******************************************/
/*
* Function to determine next transaction id.
*
* We use a library wide transaction id, which means that we
* use a new transaction id no matter what slave to which we will
* be sending the request...
*/
static inline u16 next_transaction_id(void) {
static u16 next_id = 0;
return next_id++;
}
/*
* Functions to convert u16 variables
* between network and host byte order
*
* NOTE: Modbus uses MSByte first, just like
* tcp/ip, so we could be tempted to use the htons() and
* ntohs() functions to guarantee code portability.
*
* However, on some embedded systems running Linux
* these functions only work if the 16 bit words are
* stored on even addresses. This is not always the
* case in our code, so we have to define our own
* conversion functions...
*/
/* if using gcc, use it to determine byte order... */
#ifndef __BYTE_ORDER
#if defined(__GNUC__)
/* We have GCC, which should define __LITTLE_ENDIAN__ */
# if defined(__LITTLE_ENDIAN__)
# define __BYTE_ORDER __LITTLE_ENDIAN
# else
# define __BYTE_ORDER __BIG_ENDIAN
# endif
#endif /* __GNUC__ */
#endif /* __BYTE_ORDER */
/* If we still don't know byte order, try to get it from <sys/param.h> */
#ifndef __BYTE_ORDER
#include <sys/param.h>
#endif
#ifndef __BYTE_ORDER
# ifdef BYTE_ORDER
# if BYTE_ORDER == LITTLE_ENDIAN
# define __BYTE_ORDER __LITTLE_ENDIAN
# else
# if BYTE_ORDER == BIG_ENDIAN
# define __BYTE_ORDER __BIG_ENDIAN
# endif
# endif
# endif /* BYTE_ORDER */
#endif /* __BYTE_ORDER */
#ifdef __BYTE_ORDER
# if __BYTE_ORDER == __LITTLE_ENDIAN
/**************************************************************/
/* u16 conversion functions to use on little endian platforms */
/**************************************************************/
static inline u16 mb_hton(u16 w) {
register u16 tmp;
tmp = (w & 0x00FF);
tmp = ((w & 0xFF00) >> 0x08) | (tmp << 0x08);
return(tmp);
}
#define mb_ntoh(a) mb_hton(a)
static inline void mb_hton_count(u16 *w, int count) {
int i;
for (i = 0; i < count; i++) {
/* swap the bytes around...
* a = a ^ b;
* b = a ^ b;
* a = a ^ b;
*/
((u8 *)(w+i))[0] ^= ((u8 *)(w+i))[1];
((u8 *)(w+i))[1] ^= ((u8 *)(w+i))[0];
((u8 *)(w+i))[0] ^= ((u8 *)(w+i))[1];
}
}
#define mb_ntoh_count(w, count) mb_hton_count(w, count)
# else
# if __BYTE_ORDER == __BIG_ENDIAN
/***********************************************************/
/* u16 conversion functions to use on big endian platforms */
/***********************************************************/
/* We do not need to swap the bytes around! */
#define mb_ntoh(val) (val)
#define mb_hton(val) (val)
#define mb_hton_count(w, count) /* empty ! */
#define mb_ntoh_count(w, count) /* empty ! */
# else
/********************************************************/
/* u16 conversion functions to use on generic platforms */
/********************************************************/
/* We don't know the byte order, so we revert to the
* standard htons() and ntohs() ...
*/
static inline u16 mb_hton(u16 h_value)
{return htons(h_value); /* return h_value; */}
static inline u16 mb_ntoh(u16 m_value)
{return ntohs(m_value); /* return m_value; */}
static inline void mb_hton_count(u16 *w, int count)
{int i; for (i = 0; i < count; i++) {w[i] = mb_hton(w[i]);}}
static inline void mb_ntoh_count(u16 *w, int count)
{int i; for (i = 0; i < count; i++) {w[i] = mb_ntoh(w[i]);}}
# endif
# endif
#endif /* __BYTE_ORDER */
/* Safe versions of the conversion functions!
*
* Note that these functions always work, whatever the endiannes
* of the machine that executes it!
*
* It is also safe because the resulting value may be stored
* on an odd address even on machines that do not allow directly
* accessing u16 bit words on odd addresses.
*/
static inline int mb_hton_safe(u16 from, u16 *to_ptr) {
((u8 *)to_ptr)[1] = (from & 0x00FF);
((u8 *)to_ptr)[0] = ((from & 0xFF00) >> 0x08);
return 0;
}
#define mb_ntoh_safe(a, b) mb_hton_safe(a, b)
/* return Most Significant Byte of value; */
static inline u8 msb(u16 value)
{return (value >> 8) & 0xFF;}
/* return Least Significant Byte of value; */
static inline u8 lsb(u16 value)
{return value & 0xFF;}
#define u16_v(char_ptr) (*((u16 *)(&(char_ptr))))
/***********************************************/
/***********************************************/
/** **/
/** Handle requests from master/client **/
/** **/
/***********************************************/
/***********************************************/
/* Handle functions 0x01 and 0x02 */
typedef int (*read_bits_callback_t)(void *arg, u16 start_addr, u16 bit_count, u8 *data_bytes);
static int handle_read_bits (u8 *query_packet,
u8 **resp_packet_ptr,
u8 *error_code,
read_bits_callback_t read_bits_callback,
void *callback_arg
) {
u16 start_addr, count;
int res;
u8 *resp_packet;
/* If no callback, handle as if function is not supported... */
if (read_bits_callback == NULL)
{*error_code = ERR_ILLEGAL_FUNCTION; return -1;}
/* in oprder for the data in this packet to be aligned on even numbered addresses, this
* response packet will start off at an odd numbered byte...
* We therefore add 1 to the address where the packet starts.
*/
(*resp_packet_ptr)++;
resp_packet = *resp_packet_ptr;
/* NOTE:
* Modbus uses high level addressing starting off from 1, but
* this is sent as 0 on the wire!
* We could expect the user to specify high level addressing
* starting at 1, and do the conversion to start off at 0 here.
* However, to do this we would then need to use an u32 data type
* to correctly hold the address supplied by the user (which could
* correctly be 65536, which does not fit in an u16), which would
* in turn require us to check whether the address supplied by the user
* is correct (i.e. <= 65536).
* I decided to go with the other option of using an u16, and
* requiring the user to use addressing starting off at 0!
*/
/* start_addr = mb_ntoh(u16_v(query_packet[2])) + 1; */
mb_ntoh_safe(u16_v(query_packet[2]), &start_addr);
mb_ntoh_safe(u16_v(query_packet[4]), &count);
#ifdef DEBUG
printf("handle_read_input_bits() called. slave=%d, function=%d, start_addr=%d, count=%d\n",
query_packet[0], query_packet[1], start_addr, count);
#endif
if ((count > MAX_READ_BITS) || (count < 1))
{*error_code = ERR_ILLEGAL_DATA_VALUE; return -1;}
/* Remember, we are using addressing starting off at 0, in the start_addr variable! */
/* This means that he highest acceptable address is 65535, when count=1 .... */
/* Note the use of 65536 in the comparison will force automatic upgrade of u16 variables! */
/* => start_addr + count will nver overflow the u16 type! */
if (start_addr + count > 65536)
{*error_code = ERR_ILLEGAL_DATA_ADDRESS; return -1;}
/* start building response frame... */
resp_packet[0] = query_packet[0]; /* slave */
resp_packet[1] = query_packet[1]; /* function (either 0x01 or 0x02 ! */
resp_packet[2] = (count + 7) / 8; /* number of data bytes = ceil(count/8) */
res = read_bits_callback(callback_arg, start_addr, count, &(resp_packet[3]));
if (res == -2) {*error_code = ERR_ILLEGAL_DATA_ADDRESS; return -1;}
if (res < 0) {*error_code = ERR_SLAVE_DEVICE_FAILURE; return -1;}
return resp_packet[2] + 3; /* packet size is data length + 3 bytes -> slave, function, count */
}
/* Handle function 0x01 */
int handle_read_output_bits (u8 *query_packet, u8 **resp_packet_ptr, u8 *error_code, mb_slave_callback_t *callbacks)
{return handle_read_bits(query_packet, resp_packet_ptr, error_code, callbacks->read_outbits, callbacks->arg);}
/* Handle function 0x02 */
int handle_read_input_bits (u8 *query_packet, u8 **resp_packet_ptr, u8 *error_code, mb_slave_callback_t *callbacks)
{return handle_read_bits(query_packet, resp_packet_ptr, error_code, callbacks->read_inbits, callbacks->arg);}
/* Handle functions 0x03 and 0x04 */
typedef int (*read_words_callback_t)(void *arg, u16 start_addr, u16 word_count, u16 *data_words);
static int handle_read_words (u8 *query_packet,
u8 **resp_packet_ptr,
u8 *error_code,
read_words_callback_t read_words_callback,
void *callback_arg
) {
u16 start_addr, count;
int res;
u8 *resp_packet;
/* If no callback, handle as if function is not supported... */
if (read_words_callback == NULL)
{*error_code = ERR_ILLEGAL_FUNCTION; return -1;}
/* See equivalent comment in handle_read_bits() */
(*resp_packet_ptr)++;
resp_packet = *resp_packet_ptr;
/* See equivalent comment in handle_read_bits() */
mb_ntoh_safe(u16_v(query_packet[2]), &start_addr);
mb_ntoh_safe(u16_v(query_packet[4]), &count);
#ifdef DEBUG
printf("handle_read_output_words() called. slave=%d, function=%d, start_addr=%d, count=%d\n",
query_packet[0], query_packet[1], start_addr, count);
#endif
if ((count > MAX_READ_REGS) || (count < 1))
{*error_code = ERR_ILLEGAL_DATA_VALUE; return -1;}
/* See equivalent comment in handle_read_bits() */
if (start_addr + count > 65536)
{*error_code = ERR_ILLEGAL_DATA_ADDRESS; return -1;}
/* start building response frame... */
resp_packet[0] = query_packet[0]; /* slave */
resp_packet[1] = query_packet[1]; /* function code, either 0x03 or 0x04 !!!*/
resp_packet[2] = count * 2; /* number of bytes of data... */
res = read_words_callback(callback_arg, start_addr, count, (u16 *)&(resp_packet[3]));
if (res == -2) {*error_code = ERR_ILLEGAL_DATA_ADDRESS; return -1;}
if (res < 0) {*error_code = ERR_SLAVE_DEVICE_FAILURE; return -1;}
/* convert all data from host to network byte order. */
mb_hton_count((u16 *)&(resp_packet[3]), count);
return resp_packet[2] + 3; /* packet size is data length + 3 bytes -> slave, function, count */
}
/* Handle function 0x03 */
int handle_read_output_words (u8 *query_packet, u8 **resp_packet_ptr, u8 *error_code, mb_slave_callback_t *callbacks)
{return handle_read_words(query_packet, resp_packet_ptr, error_code, callbacks->read_outwords, callbacks->arg);}
/* Handle function 0x04 */
int handle_read_input_words (u8 *query_packet, u8 **resp_packet_ptr, u8 *error_code, mb_slave_callback_t *callbacks)
{return handle_read_words(query_packet, resp_packet_ptr, error_code, callbacks->read_inwords, callbacks->arg);}
/* Handle function 0x05 */
int handle_write_output_bit (u8 *query_packet, u8 **resp_packet_ptr, u8 *error_code, mb_slave_callback_t *callbacks) {
u16 start_addr;
int res;
u8 *resp_packet;
/* If no callback, handle as if function is not supported... */
if (callbacks->write_outbits == NULL)
{*error_code = ERR_ILLEGAL_FUNCTION; return -1;}
resp_packet = *resp_packet_ptr;
/* See equivalent comment in handle_read_bits() */
mb_ntoh_safe(u16_v(query_packet[2]), &start_addr);
#ifdef DEBUG
printf("handle_write_output_bit() called. slave=%d, function=%d, start_addr=%d\n",
query_packet[0], query_packet[1], start_addr);
#endif
// byte 5 Must be 0x00, byte 4 must be 0x00 or 0xFF !!
if ( (query_packet[5] != 0) ||
((query_packet[4] != 0) && (query_packet[4] != 0xFF)))
{*error_code = ERR_ILLEGAL_DATA_VALUE; return -1;}
/* Address will always be valid, no need to check! */
// if (start_addr > 65535) {*error_code = ERR_ILLEGAL_DATA_ADDRESS; return -1;}
/* start building response frame... */
resp_packet[0] = query_packet[0]; /* slave */
resp_packet[1] = query_packet[1]; /* function */
resp_packet[2] = query_packet[2]; /* start address - hi byte */
resp_packet[3] = query_packet[3]; /* start address - lo byte */
resp_packet[4] = query_packet[4]; /* value: 0x00 or 0xFF */
resp_packet[5] = query_packet[5]; /* value: must be 0x00 */
res = (callbacks->write_outbits)(callbacks->arg, start_addr, 1, &(query_packet[4]));
if (res == -2) {*error_code = ERR_ILLEGAL_DATA_ADDRESS; return -1;}
if (res < 0) {*error_code = ERR_SLAVE_DEVICE_FAILURE; return -1;}
return 6; /* response packet size, including slave id in byte 0 */
}
/* Handle function 0x06 */
int handle_write_output_word (u8 *query_packet, u8 **resp_packet_ptr, u8 *error_code, mb_slave_callback_t *callbacks) {
u16 start_addr;
int res;
u8 *resp_packet;
/* If no callback, handle as if function is not supported... */
if (callbacks->write_outwords == NULL)
{*error_code = ERR_ILLEGAL_FUNCTION; return -1;}
resp_packet = *resp_packet_ptr;
/* See equivalent comment in handle_read_bits() */
mb_ntoh_safe(u16_v(query_packet[2]), &start_addr);
#ifdef DEBUG
printf("handle_write_output_word() called. slave=%d, function=%d, start_addr=%d\n",
query_packet[0], query_packet[1], start_addr);
#endif
/* Address will always be valid, no need to check! */
// if (start_addr > 65535) {*error_code = ERR_ILLEGAL_DATA_ADDRESS; return -1;}
/* start building response frame... */
resp_packet[0] = query_packet[0]; /* slave */
resp_packet[1] = query_packet[1]; /* function */
resp_packet[2] = query_packet[2]; /* start address - hi byte */
resp_packet[3] = query_packet[3]; /* start address - lo byte */
resp_packet[4] = query_packet[4]; /* value - hi byte */
resp_packet[5] = query_packet[5]; /* value - lo byte */
/* convert data from network to host byte order */
mb_ntoh_count((u16 *)&(query_packet[4]), 1);
res = (callbacks->write_outwords)(callbacks->arg, start_addr, 1, (u16 *)&(query_packet[4]));
if (res == -2) {*error_code = ERR_ILLEGAL_DATA_ADDRESS; return -1;}
if (res < 0) {*error_code = ERR_SLAVE_DEVICE_FAILURE; return -1;}
return 6; /* packet size is 6 -> slave, function, addr(2), value(2) */
}
/* Handle function 0x0F */
int handle_write_output_bits (u8 *query_packet, u8 **resp_packet_ptr, u8 *error_code, mb_slave_callback_t *callbacks) {
u16 start_addr, count;
int res;
u8 *resp_packet;
/* If no callback, handle as if function is not supported... */
if (callbacks->write_outbits == NULL)
{*error_code = ERR_ILLEGAL_FUNCTION; return -1;}
resp_packet = *resp_packet_ptr;
/* See equivalent comment in handle_read_bits() */
mb_ntoh_safe(u16_v(query_packet[2]), &start_addr);
mb_ntoh_safe(u16_v(query_packet[4]), &count);
#ifdef DEBUG
printf("handle_write_output_bits() called. slave=%d, function=%d, start_addr=%d, count=%d\n",
query_packet[0], query_packet[1], start_addr, count);
#endif
if ((count > MAX_WRITE_COILS) || (count < 1) || ((count+7)/8 != query_packet[6]) )
{*error_code = ERR_ILLEGAL_DATA_VALUE; return -1;}
/* See equivalent comment in handle_read_bits() */
if (start_addr + count > 65536)
{*error_code = ERR_ILLEGAL_DATA_ADDRESS; return -1;}
/* start building response frame... */
resp_packet[0] = query_packet[0]; /* slave */
resp_packet[1] = query_packet[1]; /* function */
resp_packet[2] = query_packet[2]; /* start address - hi byte */
resp_packet[3] = query_packet[3]; /* start address - lo byte */
resp_packet[4] = query_packet[4]; /* count - hi byte */
resp_packet[5] = query_packet[5]; /* count - lo byte */
res = (callbacks->write_outbits)(callbacks->arg, start_addr, count, &(query_packet[7]));
if (res == -2) {*error_code = ERR_ILLEGAL_DATA_ADDRESS; return -1;}
if (res < 0) {*error_code = ERR_SLAVE_DEVICE_FAILURE; return -1;}
return 6; /* packet size is 6 -> slave, function, addr(2), count(2) */
}
/* Handle function 0x10 */
int handle_write_output_words(u8 *query_packet, u8 **resp_packet_ptr, u8 *error_code, mb_slave_callback_t *callbacks) {
u16 start_addr, count;
int res;
u8 *resp_packet;
/* If no callback, handle as if function is not supported... */
if (callbacks->write_outwords == NULL)
{*error_code = ERR_ILLEGAL_FUNCTION; return -1;}
resp_packet = *resp_packet_ptr;
/* See equivalent comment in handle_read_bits() */
mb_ntoh_safe(u16_v(query_packet[2]), &start_addr);
mb_ntoh_safe(u16_v(query_packet[4]), &count);
if ((count > MAX_WRITE_REGS) || (count < 1) || (count*2 != query_packet[6]) )
{*error_code = ERR_ILLEGAL_DATA_VALUE; return -1;}
/* See equivalent comment in handle_read_bits() */
if (start_addr + count > 65536)
{*error_code = ERR_ILLEGAL_DATA_ADDRESS; return -1;}
/* start building response frame... */
resp_packet[0] = query_packet[0]; /* slave */
resp_packet[1] = query_packet[1]; /* function */
resp_packet[2] = query_packet[2]; /* start address - hi byte */
resp_packet[3] = query_packet[3]; /* start address - lo byte */
resp_packet[4] = query_packet[4]; /* count - hi byte */
resp_packet[5] = query_packet[5]; /* count - lo byte */
/* convert all data from network to host byte order */
mb_ntoh_count((u16 *)&(query_packet[7]), count);
res = (callbacks->write_outwords)(callbacks->arg, start_addr, count, (u16 *)&(query_packet[7]));
if (res == -2) {*error_code = ERR_ILLEGAL_DATA_ADDRESS; return -1;}
if (res < 0) {*error_code = ERR_SLAVE_DEVICE_FAILURE; return -1;}
return 6; /* packet size is 6 -> slave, function, addr(2), count(2) */
}
/***********************************************/
/***********************************************/
/** **/
/** initialise / shutdown the library **/
/** **/
/***********************************************/
/***********************************************/
int mb_slave_init__(int extra_bytes) {
buff_extra_bytes_ = extra_bytes;
return 0;
}
int mb_slave_done__(void)
{return 0;}
#if 0
int mb_slave_init(int nd_count) {
int extra_bytes;
#ifdef DEBUG
fprintf( stderr, "mb_slave_init()\n");
fprintf( stderr, "creating %d nodes\n", nd_count);
#endif
/* initialise layer 1 library */
if (modbus_init(nd_count, DEF_OPTIMIZATION, &extra_bytes) < 0)
goto error_exit_0;
/* initialise this library */
if (mb_slave_init__(extra_bytes) < 0)
goto error_exit_1;
return 0;
error_exit_1:
modbus_done();
error_exit_0:
return -1;
}
int mb_slave_done(void) {
mb_slave_done__(void)
return modbus_done();
}
#endif
/***********************************************/
/***********************************************/
/** **/
/** open/close slave connection **/
/** **/
/***********************************************/
/***********************************************/
/* Create a new slave/server */
/* NOTE: We use the lower 2 bits of the returned node id to identify which
* layer1 implementation to use.
* 0 -> TCP
* 1 -> RTU
* 2 -> ASCII
* 4 -> unused
* The node id used by the layer1 is shifted left 2 bits
* before returning the node id to the caller!
*/
int mb_slave_new(node_addr_t node_addr) {
int res = -1;
#ifdef DEBUG
fprintf( stderr, "mb_slave_connect()\n");
#endif
/* call layer 1 library */
switch(node_addr.naf) {
case naf_tcp:
res = modbus_tcp_listen(node_addr);
if (res >= 0) res = res*4 + 0 /* offset into fptr_ with TCP functions */;
return res;
case naf_rtu:
res = modbus_rtu_listen(node_addr);
if (res >= 0) res = res*4 + 1 /* offset into fptr_ with RTU functions */;
return res;
case naf_ascii:
res = modbus_ascii_listen(node_addr);
if (res >= 0) res = res*4 + 2 /* offset into fptr_ with ASCII functions */;
return res;
}
return -1;
}
int mb_slave_close(int fd) {
#ifdef DEBUG
fprintf( stderr, "mb_slave_close(): nd = %d\n", fd);
#endif
get_ttyfd(); /* declare the ttyfd variable!! */
/* call layer 1 library */
/* will call one of modbus_tcp_close(), modbus_rtu_close(), modbus_ascii_close() */
return modbus_close(ttyfd);
}
/***********************************************/
/***********************************************/
/** **/
/** Run the slave **/
/** **/
/***********************************************/
/***********************************************/
/* Execute infinite loop waiting and replying to requests coming from clients/master
* This function enters an infinite loop wating for new connection requests,
* and for modbus requests over previoulsy open connections...
*
* The frames are read from:
* - the node descriptor nd, if nd >= 0
* When using TCP, if the referenced node nd was created to listen for new connections
* [mb_slave_listen()], then this function will also reply to Modbus data requests arriving
* on other nodes that were created as a consequence of accepting connections requests to
* the referenced node nd.
* All other nodes are ignored!
*
* - any valid and initialised TCP node descriptor, if nd = -1
* In this case, will also accept connection requests arriving from a previously
* created node to listen for new connection requests [mb_slave_listen() ].
* NOTE: (only avaliable if using TCP)
*
* slaveid identifies the address (RTU and ASCII) or slaveid (TCP) that we implement.
* Any requests that we receive sent with a slaveid different
* than the one specified, and also different to 0, will be silently ignored!
* Whatever the slaveid specified, we always reply to requests
* to slaveid 0 (the modbus broadcast address).
* Calling this function with a slaveid of 0 means to ignore this
* parameter and to reply to all requests (whatever the slaveid
* used in the request). This should mostly be used by TCP servers...
*/
int mb_slave_run(int fd, mb_slave_callback_t callback_functions, u8 slaveid) {
int byte_count;
u16 transaction_id;
int nd;
u8 function, error_code = 0;
int resp_length;
u8 *query_packet = NULL;
u8 *resp_packet;
u8 resp_buffer_[RESP_BUFFER_SIZE];
u8 slave;
get_ttyfd(); /* declare the ttyfd variable!! */
#ifdef DEBUG
fprintf(stderr,"[%lu] mb_slave_run(): Called... fd=%d, ttyfd=%d\n", pthread_self(), fd, ttyfd);
#endif
while(1) {
nd = ttyfd;
/* will call one of modbus_tcp_read(), modbus_rtu_read(), modbus_ascii_read() */
do {
byte_count = modbus_read(&nd, /* node descriptor */
&query_packet, /* u8 **recv_data_ptr, */
&transaction_id, /* u16 *transaction_id, */
NULL, /* const u8 *send_data, */
0, /* int send_length, */
NULL /* wait indefenitely */ /* const struct timespec *recv_timeout); */
);
} while (byte_count <= 2);
#ifdef DEBUG
{/* display the hex code of each character received */
int i;
printf("[%lu] mb_slave_run() received %d bytes (ptr=%p): \n", pthread_self(), byte_count, query_packet);
for (i=0; i < byte_count; i++)
printf("<0x%2X>", query_packet[i]);
printf("\n");
}
#endif
slave = query_packet[0];
function = query_packet[1];
/* We only reply if:
* - request was sent to broadcast address (slave == 0)
* OR - we were asked to reply to every request (slaveid == 0)
* OR - request matches the slaveid we were asked to accept (slave == slaveid)
*
* Otherwise, silently ignore the received request!!!
*/
if ((slaveid == 0) || (slave == 0) || (slave == slaveid)) {
resp_packet = resp_buffer_;
switch(function) {
case 0x01: resp_length = handle_read_output_bits (query_packet, &resp_packet, &error_code, &callback_functions); break;
case 0x02: resp_length = handle_read_input_bits (query_packet, &resp_packet, &error_code, &callback_functions); break;
case 0x03: resp_length = handle_read_output_words (query_packet, &resp_packet, &error_code, &callback_functions); break;
case 0x04: resp_length = handle_read_input_words (query_packet, &resp_packet, &error_code, &callback_functions); break;
case 0x05: resp_length = handle_write_output_bit (query_packet, &resp_packet, &error_code, &callback_functions); break;
case 0x06: resp_length = handle_write_output_word (query_packet, &resp_packet, &error_code, &callback_functions); break;
case 0x0F: resp_length = handle_write_output_bits (query_packet, &resp_packet, &error_code, &callback_functions); break;
case 0x10: resp_length = handle_write_output_words(query_packet, &resp_packet, &error_code, &callback_functions); break;
/* return exception code 0x01 -> function not supported! */
default : resp_length = -1; error_code = 0x01; break;
}; /* switch(function) */
if (resp_length < 0) {
/* return error... */
/* build exception response frame... */
resp_packet = resp_buffer_;
resp_packet[0] = query_packet[0]; /* slave */
resp_packet[1] = query_packet[1] | 0x80; /* function code with error bit activated! */
resp_packet[2] = error_code;
resp_length = 3;
}
modbus_write(nd, resp_packet, resp_length, transaction_id, NULL /*transmit_timeout*/);
}; /* if not ignore request */
}; /* while(1) */
/* humour the compiler... */
return 0;
}